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+Project Gutenberg (https://www.gutenberg.org) public repository for
+eBook #56303 (https://www.gutenberg.org/ebooks/56303)
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-The Project Gutenberg EBook of Agate Fossil Beds National Monument,
-Nebraska, by United States National Park Service
-
-This eBook is for the use of anyone anywhere in the United States and most
-other parts of the world at no cost and with almost no restrictions
-whatsoever.  You may copy it, give it away or re-use it under the terms of
-the Project Gutenberg License included with this eBook or online at
-www.gutenberg.org.  If you are not located in the United States, you'll have
-to check the laws of the country where you are located before using this ebook.
-
-Title: Agate Fossil Beds National Monument, Nebraska
-
-Author: United States National Park Service
-
-Release Date: January 4, 2018 [EBook #56303]
-
-Language: English
-
-Character set encoding: UTF-8
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-*** START OF THIS PROJECT GUTENBERG EBOOK AGATE FOSSIL BEDS NATIONAL MONUMENT ***
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-
-                           Agate Fossil Beds
-
-
-                  Agate Fossil Beds National Monument
-                                Nebraska
-
-                            Produced by the
-                        Division of Publications
-                          Harpers Ferry Center
-                         National Park Service
-
-                    U.S. Department of the Interior
-                            Washington, D.C.
-
-
-                   The National Park Handbook Series
-
-National Park Handbooks, compact introductions to the great natural and
-historic places administered by the National Park Service, are designed
-to promote understanding and enjoyment of the parks. Each is intended to
-be informative reading and a useful guide before, during, and after a
-park visit. More than 100 titles are in print. This is Handbook 107. You
-may purchase the handbooks through the mail by writing to Superintendent
-of Documents, U.S. Government Printing Office, Washington DC 20402.
-
-
-                            About This Book
-
-What was life like in North America 20 million years ago? Agate Fossil
-Beds provides a glimpse of that time, long before the arrival of man,
-when now-extinct creatures roamed the land which we know today as
-Nebraska. Part 1 of this handbook introduces you to the park; Part 2
-brings life to the fossil specimens and examines the area’s geological
-and ecological evidence; and Part 3 presents concise guide and reference
-information.
-
-
-           Library of Congress Cataloging in Publication Data
-
-
-  United States. National Park Service.
-  Agate Fossil Beds National Monument, Nebraska.
-  (National park handbook; 107) Bibliography: p.
-  Includes index.
-  Supt. of Docs. no. I29.9/5:107
-  1. Vertebrates, Fossil.
-  2. Paleontology—Miocene.
-  3. Paleontology—Nebraska—Agate Fossil Beds National Monument.
-  4. Natural history—Nebraska—Agate Fossil Beds National Monument.
-  5. Agate Fossil Beds National Monument, Neb.
-  I. Title.
-  II. Series: United States. National Park Service. Handbook—National
-          Park Service; 107.
-  QE841.U59    1980    566′.09782′99    80-607119
-
-
-                                Contents
-
-  Part 1 Welcome to Agate Fossil Beds                                   4
-      Worlds of Past and Present                                        7
-  Part 2 A Landscape Rich With Life                                    18
-      _Text: James R. and Laurie J. Macdonald_
-      _Illustrations: Jay H. Matternes_
-      A Visit to the Past                                              23
-      The Mark of Death Upon the Land                                  35
-      The Geologic History of Agate                                    47
-      Ecology: Change and Adaptation                                   53
-  Part 3 Guide and Adviser                                             74
-      Contents for this section                                        77
-
-
-
-
-                   1    Welcome to Agate Fossil Beds
-
-
-    [Illustration: James H. Cook examines a fossil fragment at the
-    quarries near Agate Springs Ranch about 1918.]
-
-    [Illustration: Besides fossils, Cook also collected Indian artifacts
-    and kept many of them on the walls of his study in the ranch house.]
-
-
-                       Worlds of Past and Present
-
-Imagine that you are a healthy young man, raised conservatively in
-Michigan several years after the end of the Civil War. You are a skilled
-all-around hunter and trapper. The railroad has just spanned the
-continent, and stories of the West, its dangers, its people, and its
-opportunities come to you frequently. You and a friend decide you must
-see this land for yourself, and you save your money carefully against
-the day when you will be ready to go west. Around 1869, at age 12, that
-day comes.
-
-At Fort Leavenworth, Kansas, you meet several cattlemen who tell you and
-your friend where to get work as cattle herders. Before many years have
-passed you have been a cowpuncher in Texas, you have fought Comanches,
-and you have bossed a ranch crew for a wealthy Englishman. You go on to
-fight the famous Apache Chieftain Geronimo as a scout with the U.S.
-Cavalry, and you befriend a famous Sioux chief, Red Cloud. You marry,
-buy a ranch in western Nebraska, and raise a family. And you become
-something of a legend in your own time, your ranch known for its
-hospitality to Indian, scientist, traveler—to one and all, rich or poor.
-
-A movie script? Not at all—these are the essentials of the life of James
-H. Cook. Known as “Captain,” James Cook became the owner, in 1887, of
-the Agate Springs Ranch, founded earlier by his father-in-law. Under
-Cook’s watchful eye, the ranch prospered and became a second home both
-for the Oglala Sioux and for paleontologists bent on excavating the
-fossilized remains of the life of 20 million years ago, found here along
-the Niobrara River in western Nebraska.
-
-This land, now encompassing Agate Fossil Beds National Monument, is
-punctuated with low bluffs ascending westward toward the Rockies. It is
-a land of sharp contrasts, of cool, inviting riverbanks and parched
-ridges, the most famous of which are the fossil-bearing Carnegie and
-University Hills. The surrounding grassy plains are a tapestry of wild
-grasses—prairie sandreed, blue grama, little bluestem, and
-needle-and-thread. The wildflowers lupine, spiderwort, western
-wallflower, sunflower, and penstemon add touches of blue, purple,
-orange, yellow, and red to the tapestry. In summer the dark green spears
-of the small soapweed, a yucca, dot the brown grasses of the hillsides.
-And just as they did more than 20 million years ago, cottonwoods and
-willows provide shade and shelter for birds and other animals along the
-river.
-
-    [Illustration: Professor Othniel C. Marsh, back row center, of Yale
-    University and his students look as if they are equipped for a
-    frontier hunting expedition. But instead of looking for live animals
-    in the West, they were hunting for fossilized remains of ancient
-    beasts. Marsh and his crews made many such trips, and it was on one
-    early trip that Cook and Marsh met, in Sioux country.]
-
-    [Illustration: Professor Marsh and the great Sioux chief Red Cloud
-    greet each other in New Haven in 1880.]
-
-    [Illustration: Professor Edward Drinker Cope competed with Marsh for
-    the best fossils. He once made the mistake of reconstructing a
-    skeleton hind end foremost; Marsh never let him forget it.]
-
-Looking out over the rippling grasses, you grasp the fact that Nebraska
-is larger than all of New England and feel the awesome spaciousness of
-the Great Plains. The word “distance” has a different meaning here than
-it does in the East. When James Cook came to the upper Niobrara River,
-the closest town was Cheyenne, Wyoming—more than 160 kilometers (100
-miles) to the southwest.
-
-It was there, in Cheyenne, that Cook met Dr. Elisha B. Graham in 1879,
-the year Graham selected this land for a cattle ranch as an investment
-and as a summer retreat for his family. Graham named the place the 04
-Ranch, apparently because it is near the 104th meridian. Cook visited
-the ranch often in the early 1880s and courted Elisha and Mary Graham’s
-daughter Kate. They were married in 1886 and lived near Socorro, New
-Mexico, for a year before returning to Nebraska with their newborn
-child, Harold, and buying the ranch from Dr. Graham, who moved to
-California.
-
-Cook began at once to make improvements to the ranch. He planted trees
-by the hundreds and carried water to them faithfully to get them
-started. As settlers failed to “prove up” their land claims over the
-years, he added new lands to the ranch and changed the name to Agate
-Springs Ranch in recognition of the native moss agates and the many
-springs in the valley. He and Kate raised fine race horses as well as
-cattle.
-
-The period in which the Cooks took over the ranch was one of transition
-from the frontier days of migrations and Indian wars to more settled,
-orderly lives. Ranching and farming became the dominant mode of life in
-the eastern approaches to the Rockies. Even oil exploration played a
-part in the development of the land. The transition was a difficult one
-for many, Indian and settler alike.
-
-In some ways Kate Cook represented both the old and the new in Nebraska.
-She was a fine horsewoman; one day she rode a bucking horse through the
-streets of Cheyenne sidesaddle to win a bet for her husband. She was
-refined, too, having taught herself French so she could read French
-literature. Her mother, Mary Graham, became the first postmistress for
-the small community around Agate.
-
-And James Cook was more than an adventuresome frontiersman. He was
-actively interested in community and national affairs and in current
-scientific questions. He became a patient, knowledgeable mediator
-between the Indians and the settlers, and he was looked upon by the
-Oglala Sioux as a friend and host, and sometimes employer.
-
-The Cooks became involved in a great scientific enterprise quite
-accidentally around 1885, the year before their marriage. On a ride up
-the conical buttes not far from the ranch house, a glitter under a rock
-shelf caught Cook’s eye. They found fragments of bones scattered on the
-ground. At first they assumed the bones were those of an Indian. But
-Cook found instead “a beautifully petrified piece of the shaft of some
-creature’s leg bone.” They carried it back to the house but didn’t
-report the find until after they bought the ranch. Erwin Barbour of the
-University of Nebraska was the first to respond to their reports and in
-1892 became the first professional geologist to visit the area and do
-some prospecting.
-
-The Cooks’ discovery thrust them and their ranch into a subtle battle in
-the American West, a continuing struggle to find the best fossils with
-which to reconstruct the ancient past. For centuries it had been thought
-that life on our planet was only a few thousand years old, but by the
-late 19th century science had evolved beyond that point of view. Now
-paleontologists and their excavation teams were scouring the West in
-search of fossils that might provide clues to the beginnings of life.
-
-The two most noted antagonists in this feverish search were Professors
-Edward D. Cope of Philadelphia and Othniel C. Marsh of Yale University.
-Cook knew them both, but the discoveries at Agate would wait for the
-next generation of scientists.
-
-    [Illustration: University Hill, left, and Carnegie Hill dominate the
-    Niobrara River Valley. The hills received their names from the
-    paleontological teams that worked them from the University of
-    Nebraska and the Carnegie Museum.]
-
-Cook had first met Marsh in 1874. Marsh had just arrived in Oglala Sioux
-country to hunt fossils, but the Sioux Chief Red Cloud was suspicious.
-Red Cloud was convinced Marsh and his men were just another party of
-gold seekers. Cook, an able linguist, was then trailing cattle from
-Texas to the northern railroads and reservations. He persuaded Red Cloud
-that Marsh wanted only “stone bones” and averted a potentially
-disastrous clash. This incident led to a lifelong friendship between
-Cook and Red Cloud. And for Marsh this proved to be the last of many
-expeditions as he relied on others to send him specimens from likely
-fossil sites throughout the West.
-
-    [Illustration: An upland sandpiper, one of many birds that can be
-    seen at Agate Fossil Beds, perches on a fence post.]
-
-Professor Cope and his crews often worked the same localities as Marsh.
-Like Marsh, Cope tried to get the best specimens, and each occasionally
-outbid the other for them, leaving bewildered farmers and ranchers to
-puzzle over these men’s obsession with the past. Conflict also arose
-over the naming of animals previously unknown to science.
-
-The hills of Agate Springs Ranch proved to be a rich archive of ancient
-life. Dr. Barbour and his students confined their efforts to what soon
-became known as University Hill. Thus began a quiet rivalry with Olaf
-Peterson and his crew from the Carnegie Museum in Pittsburgh,
-Pennsylvania, who worked what became known as Carnegie Hill. The most
-numerous fossils these teams found at Agate are the remains of the
-pony-sized rhinoceros _Menoceras_, but the site also is known for
-fossils of the gazelle-like camel _Stenomylus_, the early small horse
-_Miohippus_, and the corkscrew burrows of an ancient beaver,
-_Palaeocastor_.
-
-Other distinguished scientists visited Agate over several decades. Among
-them were Henry Fairfield Osborn and Albert Thompson of the American
-Museum of Natural History in New York. The collections these men made at
-Agate are still being studied and exhibited.
-
-James and Kate Cook’s older son Harold caught the fever, too. He became
-a trained geologist and in 1910 married another geologist, Eleanor
-Barbour, daughter of the distinguished Nebraska geologist. The new
-generation of Cooks continued the tradition of hospitality and
-scientific interest, encouraging further excavations of the fossil
-treasures of Agate. Perhaps Harold Cook’s greatest moment of scientific
-glory came in 1926, when he and other scientists participated in the
-finds at Folsom, New Mexico, which proved to be a turning point in the
-study of the human prehistory of North America. George McJunkin, a black
-cowboy, had spotted the ribs of an animal protruding from the banks of
-an arroyo. The Folsom spearpoint and the bones of an extinct form of
-bison found there indicated that humans had lived on this continent for
-more than 10,000 years, a startling revelation at that time though today
-scientists put the figure at more than 40,000 years.
-
-    [Illustration: Next to the fence stands a windmill, which once
-    provided water for excavation teams.]
-
-    [Illustration: The narrow Niobrara River winds through the
-    surrounding tableland, carving out bluffs and exposing occasional
-    fossils.]
-
-In time the Cooks’ house became a repository for a substantial number of
-Indian artifacts and natural history specimens. On summer weekends and
-holidays tourists ventured out to the ranch to see the Cook Museum of
-Natural History. James Cook personally guided many through the
-collection, but usually the whole family participated, leading the
-curious through three rooms and a small hallway.
-
-Harold Cook wanted Agate Springs Ranch to provide an enduring memorial
-to the ancient past. Soon after his death in 1962 his second wife,
-Margaret Crozier Cook, and friends began a campaign to add the fossil
-beds to the National Park System. Their efforts succeeded in 1965, when
-Congress authorized the establishment of Agate Fossil Beds National
-Monument.
-
-Today you can walk about Carnegie and University Hills where the great
-digs took place. You can see a few exposed fossil specimens, and you can
-try to recreate in your mind the life and landscape of this part of
-Nebraska 20 million years ago. To help you do that, we have asked
-paleontologists James R. and Laurie J. Macdonald, in Part 2 of this
-handbook, to take you on a journey to the past and then examine the
-evidence.
-
-
-Welcome to the worlds of past and present at Agate Fossil Beds National
-Monument.
-
-
-
-
-                    2    A Landscape Rich With Life
-
-
-                _Text: James R. and Laurie J. Macdonald_
-                   _Illustrations: Jay H. Matternes_
-
-    [Illustration: This mural depicts life in the Agate Fossil Beds area
-    in the early Miocene Epoch, about 20 million years ago when the
-    story on the following pages takes place. The painting is a
-    composite of life at that time; if you had been there then, you
-    would not have been able to see all of these forms of life together
-    at any given moment! The original mural hangs in the fossil halls at
-    the Smithsonian Institution’s National Museum of Natural History in
-    Washington, D.C.]
-
-    [Illustration: Key to mural]
-
-
-  1/Moropus
-  2/Promerycochoerus
-  3/Menoceras
-  4/Oxydactylus
-  5/Daphoenodon
-  6/Stenomylus
-  7/Dinohyus
-  8/Merychyus
-  9/Palaeocastor
-  10/Parahippus
-  11/Syndyoceras
-
-
-                          A Visit to the Past
-
-Come enter into our imaginations and return to a day along the Niobrara
-River in western Nebraska 20 million years ago. Let’s go back and have
-an imaginary look. To set the mood, think about the wild animal movies
-made in modern Africa during the last 40 years. Think of a land swarming
-with life, of extensive grasslands dotted with trees through which great
-herds of grass- and leaf-eating animals are wandering. Look sharply into
-the shadows under the trees and amid the high grass where the
-meat-eaters are resting or stalking their prey. When you have this
-picture of wildlife in mind we’re ready for our journey into the past.
-
-Projecting ourselves back those 20 millions of years, we find ourselves
-in a landscape filled with animals. Some of the animals are not much
-different from those living today, but others are so bizarre that you
-may have a hard time believing they really existed.
-
-Dawn is building a new day, and those animals which hunt and feed at
-night are disappearing into their lairs. There are so many kinds of
-livings to be made that the day isn’t long enough for all animal
-varieties to be about and active only in daylight. As the light spreads
-over the land we see that it is an open, sunny place of mixed grasses
-and trees—mostly grassland, but here and there single trees or small
-clumps not big enough to be called groves. We would call it a savanna.
-
-A broad river runs through the land, and for lack of a better name we
-can call it the Niobrara or “Running Water,” the name given by Indians
-to the much smaller modern stream. This ancient Niobrara was a bold,
-wide stream with deep pools and sandbars. It was not cutting a valley as
-its modern counterpart is doing, but was carrying sand and silt down
-from the then-young Rocky Mountains. It sometimes flooded, and as it
-spread out over the wide, flat plain it deposited layers of sand and
-silt that geologists today call the Harrison Formation. The ancient
-Niobrara and other similar rivers spread the same sediments over nearby
-areas in eastern Wyoming and southwestern South Dakota. In the
-sediments, paleontologists would one day find millions of bones.
-
-Our ancient river was the center of life for untold numbers of animals.
-They lived in it, along its banks, in the willow thickets that grew on
-its more permanent sandbars, and on the broad, tree-dotted plains that
-stretched to the horizon beyond the river’s normal course. Great herds
-of small horses, rhinoceroses, camels, and other dwellers on the savanna
-came to water holes to drink and perhaps to wallow in the cool and
-refreshing pools. Although all else might be anticlimactic, let’s look
-at the rhinoceroses first.
-
-We know that in the modern world rhinos belong in Africa and
-southeastern Asia, not North America, yet this continent was the major
-home of these strange beasts for millions of years. Rhinos did not
-become extinct in North America until about 5 million years ago, during
-the Pliocene (see geologic time chart on page 46). Along the ancient
-Niobrara the rhino herds are not made up of the giant mammals we see in
-zoos today. The ones we see moving slowly toward the river on this early
-Miocene day are no larger than big domestic pigs. They are the first
-among the rhinos to have horns—not one behind the other, but a pair near
-the end of the nose, side by side. To scientists today these rhinos are
-known as _Menoceras_. The name _Diceratherium_, once used both for these
-small rhinos and a larger type of ancient rhino, now refers accurately
-to just the large rhino.
-
-    [Illustration: _Menoceras_]
-
-Look off to the south. There’s a herd moving slowly but purposefully
-down to its favorite watering hole. You can see that the males have the
-paired nose horns, and that the females, which are about the same size,
-do not. Trotting amid the herd are fat little colts whose seriousness of
-purpose belies their youth. The herd seems to be made up of about 50
-individuals moving through the tall grass like a flattened dark gray
-cloud. Suddenly they are startled by a large cat or dog stalking through
-the grass, and all the males on the side nearest the enemy bunch
-together to face the hungry hunter. Most of the herd continues to flow
-across the plain, and when the danger is past the guardian males catch
-up in a lumbering gallop.
-
-Finally the herd reaches the river and spreads out through the shallows.
-It is hot today, and the flies are biting even through the tough rhino
-hides. Many of the adults go into deeper pools to roll and soak while
-the young drop their serious attitudes and frolic in the shallows.
-
-As the day wears on, the herd leaves the river and feeds on the leaves
-and stems of scattered trees and willow thickets along the river. When
-twilight comes, the herd draws together, colts and females toward the
-center and bulls around the edges. After a period of milling and
-pushing, the herd finally beds down for the night, with only the
-perimeter guards moving around on the edges.
-
-The daily routines of the other herds of grass- and leaf-eating animals
-generally follow somewhat different patterns from that of the rhinos. Of
-them, only the piglike oreodons wallow in the river. The others spend
-nearly all their time out on the savanna, coming to the river only at
-dawn or dusk to drink.
-
-Oreodons were among the most abundant medium-sized animals of the Middle
-Tertiary. A strictly North American group, they have been described as
-looking like a cross between a sheep and a pig. As small as a house cat
-or as big as a domestic pig, these mammals reached a peak in abundance
-and variety between the Middle and Late Oligocene (though they are known
-from the Late Eocene through the Late Miocene). This peak probably has
-never been equalled by any other group of mammals in such a size range.
-
-As we look out among the herds of animals dotting the plain, we can see
-only a few small bands of oreodons. There’s a group coming toward us
-now. These are some big, ugly ones with large triangular-shaped heads.
-The backs of their cheek bones flare out far to the sides, so that with
-their narrow snouts they are most peculiar looking. Their bodies are
-long and rather nondescript, and their legs are short but slender. This
-particular kind is known as _Promerycochoerus_ (“before ruminant hog”)
-and is just about the largest of the oreodons. They are really a rare
-sight here at Agate. Perhaps the large herds of _Menoceras_ fill their
-ecologic niche locally, and the oreodons have found they cannot
-successfully compete with the rhinos for food, water, and living space.
-After all, not everything can fit into Paradise.
-
-    [Illustration: _Promerycochoerus_]
-
-Look to the northeast: there’s a herd of _Miohippus_ (“Miocene horse”)
-wading into the river to drink and browse in the willows along its
-banks. Let’s walk toward the herd slowly and quietly. We should take an
-especially good look at this herd—they are part of a doomed race! The
-genus _Miohippus_ is making its last stand at this time. When conditions
-change, well adapted species may restrict their ranges to what is left
-of the old environment; they may adapt, if they are able, to the new
-conditions; or they may not survive if they cannot adapt.
-
-_Miohippus_ did all these things. Some species of the genus became
-extinct. Some evolved into something else. But the end result was the
-complete termination of the genus _Miohippus_ as paleontologists
-recognize it. Much of the environmental pressure coming to bear on the
-genus _Miohippus_ was a result of mountain building to the west. As the
-young Rockies rose, rain-bearing winds from the oceans far to the west
-were wrung of their moisture. This same circumstance makes the high
-plains a land of little rain today.
-
-The scattered trees and groves we see from our vantage point of long ago
-will disappear and be replaced with a sea of drought-tolerant grasses.
-In effect, the savannas will give way to prairies. _Miohippus_ will soon
-be yielding its place to descendants which can eat grass as a steady
-diet. Grass is much harsher on the teeth than the foliage that
-_Miohippus_ eats. In eating grass, grazing animals pick up sand and silt
-enough to quickly wear away teeth designed for leaf-eating. The
-descendants of _Miohippus_ will become better runners, too, with longer
-and more powerful legs. As the trees disappear there will no longer be
-friendly clumps of greenery to hide behind when hungry meat-eaters are
-on the prowl. From now on, fleetness of foot will be a most important
-factor in horse survival.
-
-_Miohippus_ will also give rise to somewhat larger forest horses that
-will survive on into the Pliocene in patches of woodland. They will be
-little changed except in size (some came to be nearly as large as the
-modern horse), and some of them will even cross the Bering Land Bridge
-into Eurasia. This is the last time, however, that we’ll see these
-primitive horses in large numbers here in North America.
-
-There’s another herd of small horses moving across the plain toward the
-river from the south. These are feeding as they move across the savanna,
-eating both leaves from the scattered trees and grass from the prairie.
-They seem to be enjoying their mixed diet and thriving on it, so they
-won’t be too badly hurt in the geologically near future when they have
-to eat mostly grass. This is _Parahippus_ (“near horse”), a new kind of
-horse just recently evolved from _Miohippus_.
-
-    [Illustration: _Parahippus_]
-
-_Parahippus_ is a horse of destiny. For a long time some individuals of
-_Miohippus_ carried a little extra wrinkle of enamel on the crowns of
-their upper grinding teeth—and now the wrinkle occurs in all individuals
-of _Parahippus_. Because of it, _Parahippus_ can eat grass without
-wearing out its teeth before reaching breeding age, making it possible
-for most individuals to reproduce before dying. The little wrinkle is
-passed on. It’s only a small advantage, but such is the stuff that
-survival and evolution are made of. _Parahippus_ is the forerunner of a
-vast array of different three-toed, long-limbed prairie horses that will
-be the most numerous members of their family until nearly the end of the
-Pliocene. From one of their descendants will come the first one-toed
-horse—the direct ancestor of our modern horses.
-
-More herds are moving in on the river as the morning grows. There’s a
-group of something very small moving through the tall grass, but it’s
-completely hidden. Only the swaying of the 60-centimeter-tall blades
-shows that a number of animals are hurrying toward the river. Now
-they’ve moved out into an area of cropped grass, and we can see a herd
-of the diminutive deerlike _Nanotragulus_ (“dwarf goat”). Not a great
-deal larger than a house cat, these little “deer” have tall grinding
-teeth well adapted for grass-eating. Their ancestry goes back for
-millions of years into the Late Eocene, when some of their ancestors
-stood less than 15 centimeters (6 inches) high at the shoulder. But
-their entire family is soon to become extinct. They are part of the
-grazing community, although they eat leaves and softer vegetation just
-as readily. We call them “deer” because they look just like miniature
-deer, but the two families are really only distantly related.
-
-As this group scampers toward the river, we can see that they have a
-peculiar crouching gait—their forelegs are so much shorter than their
-hind legs that they seem to be running continuously downhill. They are
-dainty little animals with small, delicate heads and short, slender
-limbs. They can bound swiftly away if danger threatens, but they’d
-rather hide in the thick brush. A few of the females have fawns with
-them, tiny things less than 10 centimeters (4 inches) tall. Look at them
-all scatter! The shadow of a hawk has passed over the group, and in
-their fright they’ve dived for some nearby willows. Young _Nanotragulus_
-either learn to duck down at the sight of a passing shadow or they don’t
-get a chance to learn at all. This time they all got away, and the hawk
-will have to look elsewhere for a meal.
-
-Buteos or buzzard hawks are common along the Niobrara in the Early
-Miocene, sailing on the warm updrafts on broad, short wings that let
-them ride the lightest airs. They swoop down on the mice and pocket
-gophers, young rabbits and beavers, baby “deer” and sometimes careless
-birds that live on this savanna. All manner of meat-eaters depend on the
-small animals for food, and the little _Nanotragulus_ are most
-vulnerable as they move through the canopy of grass.
-
-There don’t seem to be any other herds moving into view just now; but
-while we’re on the subject of birds, over there in that patch of short
-grass is a bird rarely seen in North America anymore. It’s a guan, a
-ground-living bird related to the grouse and sagehens. It must be far
-from home this morning; most of its time is spent in the thick brush
-farther back from the river. A heavy body and long neck and tail make
-this animal easy to identify.
-
-    [Illustration: _Oxydactylus_]
-
-Let’s look at some of the individuals and small groups that are moving
-or resting within view. The camels with the very slender legs and long
-necks are called _Oxydactylus_ (“sharp finger”). They are browsing on
-the willows where the herd of Nanotragulus ran to hide. _Oxydactylus_ is
-an important camel, standing about at the midpoint in the evolution of
-this North American family of mammals. The camels will remain
-stay-at-homes in the continent of their origin until they spread into
-Eurasia and South America at the beginning of the Pleistocene Epoch,
-some 17.5 million years after the rhinos died out at Agate. There are
-many species of _Oxydactylus_; the one we are looking at stands about
-1.2 meters (4 feet) high at the shoulder. Notice that they don’t have
-humps on their backs; in this lush land there is no need to store fat
-against a time of possible starvation.
-
-    [Illustration: _Stenomylus_]
-
-Speaking of camels, here comes a herd of _Stenomylus_ (“narrow tooth”)
-bounding through the tall grass on the south bank of the river. This is
-a strange little long-neck camel that strayed off the main line of the
-family’s evolution. Less than 60 centimeters (24 inches) high at the
-shoulder, it looks very much like the living African antelope called the
-gerenuk. _Stenomylus_, with its long and delicate legs and tall
-cheek-teeth, is perfectly adapted for living in and eating the abundant
-grass which billows on this tree-dotted plain. Yet many of the little
-_Stenomylus_ are going to share a tragic time with hundreds of
-_Menoceras_ only a year or so from this day we are visiting. Later,
-we’ll move ahead to that time so you can see that natural disaster, now
-preserved in rock, as it happened.
-
-When you travel back 20 million years in time you would expect to find
-unbelievably bizarre animals. So far, we’ve seen some offbeat specimens,
-but there has been nothing really out of this world. Now, if you look to
-the north by the lone oak tree, you will see a real prize. Do you see
-that hulk stepping out of the shade? No, it isn’t the Dragon of the
-Ishtar Gate, though it might pass for a mythical beast. What a wonderful
-animal! A head like a large horse’s, a neck somewhat slimmer, long front
-legs, sloping back, short hind legs, and a little switch tail. Watch
-with your field glasses when it moves out onto the bare ground. See the
-feet? They don’t have hooves; each toe ends in a great curved claw! This
-is one of the fabulous chalicotheres, a relative of the horses and the
-rhinos. There were never very many of them living at one time, but the
-family lived in Eurasia from the Eocene, some 55 million years ago,
-through the Pleistocene; and here in North America from the Late Eocene
-to the Middle Miocene.
-
-    [Illustration: _Moropus_]
-
-This chalicothere is named _Moropus_ (“sloth foot”), and it is little
-wonder that when paleontologists first discovered his foot bones
-(without an associated skull) they thought they had found the feet of a
-ground sloth. Let’s watch _Moropus_ as it ambles slowly across the
-plain, its strange stilted walk a little like that of the modern
-giraffe. Other animals move aside as _Moropus_ strides through the
-grass. He’s a browser, an occasional grass-eater, and even a digger of
-easily accessible roots and tubers. Like his cousins the rhinos, he
-isn’t at all bright, and he has a very short temper. When he’s annoyed,
-he kicks out with those claws and every animal with good sense leaves
-him alone. He’s respected by meat-eaters and plant-eaters alike. He
-walks by himself and everything else detours around him.
-
-    [Illustration: _Dinohyus_]
-
-Look down toward the river, and we may see an exception. That two-meter
-(six-foot) high “pig” walking away from the river, covered with mud, is
-heading right toward the _Moropus_. His name is _Dinohyus_ (“terrible
-pig”), and he’s just as short-tempered and stupid as _Moropus_. He looks
-like a giant peccary, but his size and over-large head give him away as
-an entelodont (“complete tooth”). These are pig-like animals, usually of
-large size, that aren’t related to the domestic pigs at all. _Dinohyus’_
-skull is nearly one meter (three feet) long, and those tusks are as
-thick as a man’s wrist. Though we missed seeing him earlier, he must
-have been wallowing in the mud under the overhanging willows. Now he’s
-heading away from the river in search of lunch. He’s not very choosy
-about what he eats; it might be succulent leaves or fruits, or even the
-carcass of a dead animal. _Dinohyus_ is an omnivore, eating almost
-anything that has nourishment.
-
-Right now it looks as though he’s on a collision course with the
-_Moropus_. He’s seen the larger animal, has stopped in his tracks, and
-is pawing the ground with his front feet. Up goes his head—and listen to
-that roar! He’s getting a good temper worked up. Off he goes at a full
-gallop, right toward the _Moropus_. It’s hard to believe that an animal
-as big as that pig could charge so fast. And look at the _Moropus_! He’s
-finally realized in his dim way that he’s about to be attacked. Up he
-goes on his hind legs, holding his front legs out ready for a downward
-blow with all eight claws. But suddenly _Dinohyus_ shifts his course
-just slightly, lets out another loud bellow as he avoids the _Moropus_,
-and thunders off toward the open prairie.
-
-_Dinohyus_ has a smaller relative around here somewhere, a little fellow
-just over one meter (three feet) high, called _Entelodon_. His head is
-long and low and has flaring cheekbones and bumps along the underside of
-the jaw like his larger cousin’s. Another pig that lives along the
-Niobrara is _Desmathyus_ (“bond [filling a gap] pig”), a true North
-American pig or peccary. Its appearance probably wouldn’t surprise
-anyone; it looks very much like the peccaries that live in the American
-Southwest today. Its distant cousin, the domestic pig, was domesticated
-in the Old World from a European species of wild hog, and it was spread
-throughout the world by European colonists. In America, peccary
-evolution has run a long and conservative path. This group has changed
-relatively little in the 35 million years since it first appeared in the
-Late Eocene.
-
-    [Illustration: _Syndyoceras_]
-
-Now for another weird and wonderful beast! Trotting daintily out of a
-thicket on our left is a herd of something you might think were deer or
-pronghorn. But if you look closely you’ll see that they have two pairs
-of curving, unbranched horns on their heads, not the single pair of
-prongs you’d expect on a pronghorn. These are _Syndyoceras_ (“together
-horn”), members of a family of mammals found only in North America and
-now extinct. Even on the Early Miocene day we’re visiting, they are
-scarce, moving only in small herds. The rear pair of horns is not
-remarkable, but the front ones, which rise from a large bump near the
-nose, curl up and away from each other, ending in blunt tips.
-
-The first member of this family was _Protoceras_, which lived in the
-hills and mountains of western South Dakota during the Late Oligocene,
-just a few million years before the day we are visiting at Agate.
-Paleontologists have found battered scraps of its skeletons in the White
-River Badlands where perhaps they were washed by heavy spring rains
-running off the hills to the west. _Protoceras_ had six bony bumps on
-its head that presumably bore short horns; one pair was over the nose,
-another was over the eyes, and a third was near the back of the skull.
-Probably it was the direct ancestor of _Syndyoceras_.
-
-If _Syndyoceras_ fails somehow to qualify as grotesque, let’s jump a few
-million years into the “future” and look at his Late Miocene descendant,
-_Synthetoceras_ (“combined horn”). Here was an animal on a par with
-unicorns and cyclopses. Like _Syndyoceras_ he had two tall horns at the
-back of his head; but something had happened to the curved ones on his
-nose. They had, during several million years of evolution, grown
-together into a single shaft and then spread out again to the sides and
-up. What a pity there were no little boys then, for here we have the
-world’s first and only self-propelled slingshot! Tie a rubber band to
-the tips of his nose horns, fill your pocket with pebbles, and saddle
-up.
-
-You may be wondering by now about the smaller animals—the rodents and
-small carnivores. We have not seen any of them so far. Most carnivores
-work at night, but there should be a few about. Down by the river is a
-pair of _Oligobunis_ (“little cusp”) hunting near the water’s edge. They
-look something like modern badgers but are really more closely related
-to the weasels. If you look just to the right of the herd of
-_Stenomylus_ we were following earlier you might be able to catch a
-glimpse of a stalking cat about the size of a mountain lion. It’s
-probably either an advanced _Nimravus_ (“ancestral hunter”) or an early
-_Pseudaelurus_ (“false cat”), but we’ll have to get a closer look before
-we can be sure. Whichever it is, it’s on the main line of cat evolution
-and will eventually end up in our familiar _Felis_ and the other living
-cats. There should also be some sabretooth cats lurking about; they are
-found in nearby deposits of the same age, though not at Agate itself.
-
-    [Illustration: _Daphoenodon_]
-
-If you look very closely at the thicket just south of us on the hillside
-you can see several fox-like dogs hunting rodents. This _Nothocyon_
-(“false dog”) seems to have filled approximately the fox niche during
-the Early Miocene. Some coyote and wolf-sized dogs are in the area too.
-_Daphoenodon_ (“blood-reeking tooth”) is about coyote size. _Temnocyon_
-(“cutting [tooth] dog”), is a little larger, probably substituted for
-the wolf in the local fauna, and is characterized by its heavy head and
-long, strong jaws. If we could get a close look at its teeth, we would
-see that they are like those of the Cape Hunting Dog living today in
-South Africa.
-
-Let’s move away from the river a half-kilometer (0.3 mile) or so and see
-if we can find something different. That thicket ahead might produce a
-couple of rabbits. Look, there at the edge of the thicket: a _Nothocyon_
-has caught something. It’s a _Meniscomys_ (“crescent mouse”), an early
-relative of the living mountain beaver _Aplodontia_. Today, a single
-species of _Aplodontia_, the last of the line, is found only in the
-mountains of the West Coast. It’s the most primitive living rodent, not
-related to the Canadian beaver, and sole survivor of a suborder which
-was the earliest rodent group to evolve. _Meniscomys_ was one of the
-most prominent members of the group during the Miocene. It had a round
-furry body, a round head with protruding incisors a bit like a true
-beaver’s, and no visible tail.
-
-Watch your step. There is the mound of a pocket gopher. It is neither
-our familiar western gopher _Thomomys_ (“heap mouse”) or the “eastern”
-pocket gopher of the Great Plains, _Geomys_ (“earth mouse”), but an
-ancient relative, _Gregorymys_ (“Gregory’s mouse”). It must be pretty
-successful as a burrowing animal, because we find it all over the
-western United States in the Early Miocene.
-
-    [Illustration: _Palaeocastor_]
-
-A hundred meters (300 feet) more and we’ll show you the surprise of the
-day. Here we are in what looks like a prairie dog town. But those aren’t
-prairie dogs. They’re a little larger, and quite unfamiliar by modern
-standards. Can’t guess what they are? These are beavers—_Palaeocastor_
-(“ancient beaver”) to be exact. Here in the Early Miocene of North
-America, beavers don’t build dams. In fact they live neither at the
-water’s edge nor, like muskrats, in the water. They dig deep, spiral
-burrows in well drained ground. Some of their burrows are 2.5 meters (8
-feet) deep, but 2 meters (6.5 feet) is about average. Down and around
-and around the burrows go, like giant corkscrews, always ending in
-straight shafts slanting slightly upward so that living chambers will
-not be flooded by rainwater running down the burrows.
-
-Paleontologists have called the preserved burrows “devil’s
-corkscrews”—_Daemonelix_—since the time they were first found. At first,
-scientists thought they might be holes left by the giant tap roots of
-some unknown plant. But when _Palaeocastor_ skeletons were found in the
-bottoms of the spirals, almost everyone had to concede that they were
-truly beaver burrows. Admittedly, the skeleton of a _Nothocyon_ was
-found in one burrow; but this predator probably followed a beaver home
-for supper and just stayed. Three other kinds of beavers lived around
-Agate in the Early Miocene, but their bones have never been found in the
-burrows. No one knows what they did for homes: perhaps their burrows
-were much shallower or were in the river banks where running water soon
-destroyed them.
-
-Near the river bank in some soft sand is a nest of tortoise eggs. The
-hot sun has brought the babies out of their shells and they’re stumbling
-off in all directions. Right now the biggest is only about twice the
-size of a silver dollar; but when they’re grown they’ll be about 60
-centimeters (24 inches) across the shell, or perhaps even larger.
-They’re strict vegetarians, grazing and browsing on soft plants and
-leaves. There are probably some pond turtles around too, but we’ve never
-seen any.
-
-A little farther up the bank, under the roots of that big walnut tree,
-is a rabbit’s burrow. Several _Palaeolagus_ (“ancient rabbit”) live
-there with their many offspring. Although they look very much like
-cottontails, their ears are smaller and they haven’t the same leaping
-and running ability. They’d much rather hide than flee their enemies.
-
-
-These dwellers of the savanna, common during the Miocene Epoch, comprise
-the major species found at the Agate Fossil Beds. Their discovery in the
-late 1800’s and early 1900’s was highly important to the young science
-of paleontology. In those decades of major discoveries, large gaps
-remained in the story of evolution. Quarries like those at Agate helped
-provide the missing pieces of the puzzle. In their time, the discoveries
-at Agate were an important contribution toward understanding the world
-far beyond the dawn of mankind.
-
-Today, advances in paleontology still depend primarily upon major field
-discoveries, but paleontologists also make use of highly refined
-analytical and measurement techniques. Closely connected with
-paleontology are several other sciences, among them geology, zoology,
-and botany. The paleontologist, for example, must depend on geology to
-provide important answers about the age of fossil specimens. Fossil
-botanical specimens, in turn, can provide answers about animal diets and
-climate. Though paleontology may center on the study of fossil remains,
-it is an interdisciplinary science. This fact will become increasingly
-apparent in the following chapters, which reveal the strands of evidence
-used in constructing the picture of Miocene Agate.
-
-
-                    The Mark of Death Upon the Land
-
-Even in Paradise an occasional calamity can occur. Agate’s misfortune
-appeared in the form of a drought. To the west of the plain built by the
-ancient Niobrara River, the Rocky Mountains began to rise again. This
-renewed uplift, after millions of years of relative quiet, eventually
-led to an even drier climate and a replacement of the savanna with a
-landscape of unbroken grasslands from the mountains to the Mississippi
-River and beyond. Trees then could survive only on canyon slopes along
-the courses of the few large remaining rivers that crossed the plains.
-Those rivers flowed toward the central lowlands of North America, once
-an embayment of the Gulf of Mexico. This Mississippi Embayment, as it is
-called by geologists, extended as far north as the present location of
-Cairo, Illinois.
-
-During the first rumbles of this upheaval there were occasional
-instabilities in the weather of the Great Plains. From the fossil
-evidence of Carnegie Hill, University Hill, and the _Stenomylus_ quarry,
-we can see that drought touched the land.
-
-What happens when disaster stalks the land? That question, so pertinent
-to an understanding of fossil deposition at Agate, can be answered best
-by looking at the normal scheme of life. Animal populations are cyclic,
-increasing rapidly to near the highest numbers which can be supported on
-available food supplies. If times are good, animal populations can be
-quite high. If the food supply decreases, massive dieoffs result.
-Successive cycles of plenty and poverty then produce high populations
-followed by dieoffs.
-
-The fossil evidence suggests that a prolonged drought occurred during
-the Golden Age at Agate, resulting in death everywhere. The vast numbers
-of rhino skeletons preserved at Carnegie Hill and University Hill
-provide paleontological evidence that the drought must have lasted for
-several years.
-
-Climates change slowly, and there are wet and dry cycles. Every rancher
-and farmer discovers this when he plows new land during a wet cycle, for
-sooner or later drier years catch up with him. He expects the optimum to
-be the standard; but he is badly hurt during average times, and really
-suffers when the dry years come. It is the same with populations of wild
-animals. When the times are good and the grass and trees are lush, fat,
-and green, more of the young survive and the whole population
-flourishes. The plant-eaters expand their herds and the meat-eaters
-increase to keep up with the better food supply the plant-eaters
-provide. In each case the standards for survival are lowered, and the
-less than perfect can survive and in turn produce young of their own.
-But when the water fails and plants refuse to grow, the herbivores
-starve and the carnivore population in turn declines. Nature is
-indifferent—neither cruel nor kind. When times are bad every species is
-improved, for the strongest and most tenacious survive to reproduce
-themselves. There are benefits to hardship.
-
-So it was at Agate only a year or so after the day of our visit. The
-river died for a while. As with many rivers much of its water flowed
-beneath the surface, through the sand and gravel of the bed. When the
-ancient Niobrara died there was still water moving through the sands and
-filling the low spots in its bed. Some animals could dig down to it and
-survive, others could stake claims to the diminishing water holes. So
-the thirsty, suffering herds of _Menoceras_ went to the river and found
-no water. The strong held the water holes. The smart dug into the sand
-and made their own water holes. The rest died. They died by the
-hundreds, and thousands. Mixed with the carcasses of _Menoceras_ were
-other victims: occasional chalicotheres, giant pigs, oreodons, cats,
-dogs, and a variety of equally thirsty smaller animals. Perhaps most of
-the animals went farther up or down stream, or perhaps they chose not to
-die at the river. Whatever the pattern of dying might have been, we know
-that _Menoceras_ left untold numbers of skeletons on the broad, flat,
-and dry bottom of the ancient Niobrara.
-
-Finally the rains fell in the mountains to the west. The river filled
-with water again and ran in sheets across the plain. At Agate the
-millions of _Menoceras_ bones and lesser numbers of the bones of other
-animals were swept for a few hundred meters downstream and into some
-sort of backwater or river lake—possibly a great meander, or an oxbow
-lake. There, like a gigantic mass of jackstraws, they were piled in a
-tangled mat 30 centimeters (12 inches) thick, covering an unknown number
-of hectares. All we really know is that they were moved far enough to
-get thoroughly jumbled, but not far enough to be badly broken or much
-eroded by the action of the water.
-
-The mass of bones was soon buried by the sands and silts dropped by the
-reborn river, and by wind-carried debris swept off the parched land.
-Once buried, the bones were partially petrified by mineral water flowing
-beneath the surface. The land was built up a few hundred meters by
-sediments continually brought down from the mountains to the west.
-Eventually, continued uplifts of the Rockies and the Great Plains
-combined with erosional cycles to leave the modern Niobrara River. The
-two erosional remnants known today as Carnegie and University Hills were
-produced by the cutting of the modern river system. On the sides of
-these hills were exposed the tangle of bones which marked the site of
-ancient tragedy.
-
-But this wasn’t the only scene of mass death to be preserved here in the
-fossil record. A few kilometers away an earlier drought took a toll of
-many other animals. The little gazelle-like camel _Stenomylus_ tells the
-same story in scores of skeletons east of the _Menoceras_ burial ground.
-
-These graceful little camels may have died at the edges of their
-vanished water hole. The skeletons are mostly undisturbed except for a
-few pulled apart by meat-eaters. Scores of their dried out, mummified
-carcasses were buried about the same time as the rhinos on the river’s
-dry bottom. Like the _Menoceras_, the camels lay there for millions of
-years, intact in their death poses, the muscles in the backs of their
-necks pulling their heads back sharply into an unnatural position. There
-they lay until men discovered them.
-
-Our imaginary journey into the past has reached its end. We have seen a
-day at Agate as it might have been 20 million years ago. We have watched
-the animals going about their daily lives during times of plenty and
-have seen it as it was later, when death’s heavy hand left a magnificent
-fossil heritage. This unique place is a window into the past, a window
-through which we can look back at any time and observe life at Agate
-millions of years ago.
-
-
-                      Excavations at Agate Springs
-
-  The first fossils were collected in volume in 1904 by Olaf Peterson of
-  the Carnegie Museum in Pittsburgh. Excavations have continued, off and
-  on, to the present. As early as 1892, Erwin Barbour’s student F. C.
-  Kenyon had retrieved a few bones from the site but their significance
-  was overlooked. Rancher James Cook first picked some up in the 1880s
-  and may have first noticed such deposits, without particularly
-  recognizing them, in the 1870s.
-
-  Other institutions soon joined Carnegie in extracting slabs of the
-  great _Menoceras_ bone-bed, and occasional _Moropus_ and _Dinohyus_
-  specimens. The University of Nebraska opened a new quarry in 1905.
-  Henry Fairfield Osborn, president of the American Museum of Natural
-  History and one of the greatest popularizers and exponents of
-  evolutionary science, and his chief preparator Albert Thomson began
-  work in 1907. F. B. Loomis of Amherst College discovered the nearby
-  _Stenomylus_ quarry the same year. Yale University’s R. S. Lull soon
-  followed.
-
-  From 1911 to 1923 the American Museum became the main excavator at
-  Agate, but increasingly their attention was drawn elsewhere, including
-  the later Miocene Snake Creek Beds 20 miles to the south. There, for
-  awhile, great excitement centered around a worn tooth thought to be
-  from an early human ancestor until the tooth was proven to be from an
-  ancient peccary.
-
-  Until 1981, only occasional excavations for bonebed slabs and
-  _Stenomylus_ marked the next 50 years. Then, Robert M. Hunt Jr. of the
-  University of Nebraska reopened the main quarries and a little-known
-  side area, and found evidence of an extensive carnivore den of the
-  beardog _Daphoenodon_.
-
-  In some cases, individual fossil bones were removed one by one, a very
-  slow and painstaking process but when possible large blocks of
-  fossil-bearing sediments were removed and shipped to laboratories for
-  cleaning and analysis. The tools, chemicals, and special conditions
-  necessary to extract the best specimens and most complete information
-  are available only in a laboratory such as the one which is shown on
-  pages 40 and 41 at the Carnegie Museum in Pittsburgh, Pennsylvania, in
-  1905. Slabs from Agate Fossil Beds were taken there so paleontologists
-  could examine the evidence and figure out the past.
-
-  See pages 86-87 for a listing of museums with specimens from Agate
-  Fossil Beds.
-
-    [Illustration: Extracting a slab]
-
-    [Illustration: Members of Peterson’s crew built a box around a slab
-    in the _Stenomylus_ quarry around 1908 in preparation for shipping
-    to the Carnegie Museum.]
-
-    [Illustration: With a team of horses, O. A. Peterson’s field crew
-    moves dirt out of the _Stenomylus_ quarry around 1908. The boxes in
-    the foreground are resting on the quarry’s lower bone layer. Several
-    specimens to the left have been strengthened with plaster for
-    shipment to Pittsburgh.]
-
-    [Illustration: Crates of prepared specimens had to be taken to
-    Harrison, 37 kilometers (23 miles) north of Agate for the rail trip
-    to the East. Note that the wagon is just a flat platform and that
-    the driver is using the largest crate as a seat.]
-
-    [Illustration: Paleological laboratory.]
-
-
-                     The Beginnings of Paleontology
-
-  Paleontology is the study of ancient life through the fossil remains
-  of that life. Today, there are thousands of museums, societies,
-  professional groups, and academic institutions around the world
-  devoted to this study. Fossil remains are still being dug out of the
-  ground in a number of localities, such as Dinosaur National Monument
-  in Utah, but by far the great bulk of fossils now being studied were
-  excavated during the last 100 years.
-
-  There are now about 250,000 known separate species of fossil plants
-  and animals. Biologists are still working to explore, find, and
-  classify all living species; they estimate that 4,500,000 species of
-  plants and animals are now living at our own brief moment in the
-  nearly five billion years of our planet’s history. As you can see, the
-  fossils now known represent only a tiny fraction of all the plants and
-  animals that have ever lived. Yet a great deal is now known about even
-  the simple forms of life more than three billion years ago.
-
-  How has this come about? What has happened since the days of our
-  great-grandfathers to cause this vast increase in knowledge? Men must
-  have picked up and discussed fossils for tens or perhaps hundreds of
-  thousands of years. We have no way of knowing what the earliest men
-  thought about them. Their significance has been revealed slowly in the
-  way we tend to look at time, but perhaps not so slowly when we
-  consider how short a period man himself has been on Earth.
-
-  Lucretius, a Roman writer of the first century B.C., thought that the
-  Earth was very young. He interpreted the fossils known to him as the
-  remains of monsters that had grown out of the Earth just after it came
-  into existence. Evidently he had seen partial fossils and believed
-  them to be whole, because he postulated that the Earth had brought
-  forth creatures that lacked one or more limbs or other body parts.
-  Lucretius assumed, as have many others, that the varieties of animals
-  he knew of were fixed for all time and did not change. But he did
-  recognize the principle of evolution, that things change as time goes
-  on, in his description of human history.
-
-  Lucretius described four ages of human life, progressing from early
-  hunters up to the highly civilized life he knew under the Roman
-  Republic. His work was rediscovered during the European Renaissance,
-  when scholars once again began to inquire into the nature of seemingly
-  inexplicable things like fossils.
-
-  Toward the end of the 18th century the confusion over the importance
-  of fossils and their relative antiquity forced a scientific showdown.
-  For hundreds of years, fossil bones of extinct animals unlike any ever
-  seen had been turning up, often with tools nearby that appeared to
-  have been shaped by human hands. A growing feeling that the Earth and
-  therefore the fossils were very old indeed was a topic of frequent
-  discussion in Europe and in the New World, despite the assertion by
-  Archbishop Ussher a century earlier that the Earth was not quite 6,000
-  years old.
-
-  Explorers and scientists had found fossils in deep layers of rock
-  widely separated by other layers of rock, leading many of them to
-  conclude that now-extinct forms of life had existed before the
-  Biblical flood. A pioneer French paleontologist, Georges Cuvier, tried
-  to solve this dilemma in the late 1700s by postulating that there must
-  have been several worldwide floods before the one described in the
-  Christian Bible. Finally, this solution collapsed under the weight of
-  new evidence as more and more studies proceeded.
-
-  In the 1830s an English geologist, Sir Charles Lyell, popularized the
-  principle of uniformitarianism—the idea that processes we observe now,
-  such as the steady erosion of mountains, the gradual buildup of silt
-  as sediments in rivers, lakes, and oceans, have always occurred since
-  the origin of the Earth. This, he then reasoned, meant that the Earth
-  must be many millions of years old at least, instead of merely a few
-  thousand years old.
-
-  A wave of interest in fossils and their antiquity swept communities
-  around the world in the 1840s and 1850s. Americans interested in
-  science from Thomas Jefferson on had advocated the collection and
-  study of fossils, and a feverish race to build up study collections
-  got underway that lasted into the 20th century. Today, scientists
-  believe the Earth is more than 4.5 billion years old, its life more
-  than 3 billion years old.
-
-    [Illustration: Karl Von Linné, 1707-1778, is known as Linnaeus after
-    the Latin form of his name. A Swedish botanist, he established a
-    hierarchical system for classifying plants and animals that is still
-    in use in a modified form. His organizing principle was the degree
-    of complexity of the organisms he studied. This resulted in a system
-    with seven levels: Kingdom, Phylum, Class, Order, Family, Genus, and
-    Species, in descending order from the broadest category to the most
-    specific. Students remember the system by the sentence “King Philip
-    Crossed the Ocean For Good Soup.” Without realizing it, Linnaeus
-    prepared the ground for the evolutionists, who later were able to
-    demonstrate the gradual ascent of life forms from simple to complex
-    by using his scheme of classification.]
-
-    [Illustration: Jean-Baptiste de Lamarck, 1744-1829, a French
-    physician and ex-military man, founded the modern study of animals
-    without backbones and coined the term invertebrates to describe them
-    as a group. When his battle wounds forced him to take up a new
-    career, he studied botany and published a study of French plants. He
-    later turned to invertebrates, and between 1815 and 1822 published
-    the classic _Histoire naturelle des animaux sans vertèbres_. He
-    applied his vast knowledge of living invertebrates to
-    paleontological work, greatly enhancing the knowledge of fossil
-    invertebrates. Lamarck was also an evolutionary theorist, and he
-    believed that a single characteristic acquired by an animal during
-    its lifetime could be passed on to its descendants by heredity
-    (modern genetic theory was unknown at that time). He saw that
-    evolution must have taken a long time to occur, and he supported the
-    principle which has since become known as uniformitarianism.]
-
-    [Illustration: Georges Cuvier, 1769-1832, was a French anatomist and
-    paleontologist who specialized in the study of animals with
-    backbones, the vertebrates. He had a long and brilliant career as a
-    professor, eventually becoming France’s minister of the interior in
-    1832. His skill as a comparative anatomist enabled him to understand
-    how vertebrate fossils should be reconstructed to form a complete
-    skeleton, and he was one of the first to use the small muscle scars
-    on fossil bones to reconstruct the extinct animal’s musculature. His
-    classic work _Récherches sur les Ossemens Fossiles de Quadrupèds_
-    was published in 1812. He is known for his theory of a series of
-    natural catastrophes, each supposedly obliterating all extant life,
-    to account for the great variety of ancient fossils. This theory was
-    later supplanted by the theory of continuous evolution supported by
-    Darwin, Lyell, and others.]
-
-    [Illustration: Charles Darwin, 1809-1882, is today a household name
-    that is still invoked in controversy as it was more than a hundred
-    years ago. An extraordinarily patient and insightful biologist,
-    Darwin contributed the idea of natural selection, the “weeding out”
-    of unfit individuals and species, and described it as the guiding
-    principle of the evolution of life on this planet. His book _On the
-    Origin of Species by Means of Natural Selection_, published in 1859,
-    is the most important landmark in evolutionary studies. This was the
-    culmination of decades of work, leading to conclusions startlingly
-    similar to those of his fellow Englishman, Alfred Wallace. Darwin
-    knew nothing of the genetic principle of biological heredity and
-    variation, which has now assumed equal importance with natural
-    selection in the study of the evolution of life. For
-    paleontologists, Darwin’s work meant they must look for transitional
-    forms of life and not content themselves with Cuvier’s assumptions
-    that past life forms had been static and unchanging. During his
-    travels in South America, Darwin contracted a disease, now known as
-    Chagas’ disease, and suffered intense pain and discomfort the rest
-    of his life. He died of a heart attack on April 19, 1882, and was
-    buried in Westminster Abbey in London a few days later.]
-
-    [Illustration: Charles Lyell, 1797-1875, revolutionized the study of
-    geology partly by publicizing the earlier work of James Hutton, who
-    died the year Lyell was born in Scotland, and partly by infusing the
-    science with his own highly disciplined point of view. His greatest
-    contribution was the firm establishment of Hutton’s principle of
-    uniformitarianism, or uniformism, which became the foundation for
-    all modern geological work. Put simply, this is the principle that
-    the processes we see operating to form and shape the Earth today
-    have always operated in the past. Once this is admitted, it becomes
-    clear that past geological time is vast, not short, a truly stunning
-    notion for Lyell’s time but a commonplace fact today. The first
-    volume of his _Principles of Geology_ was published in 1830; in his
-    later works he championed Darwin’s own revolutionary point of view,
-    adding his own powerful arguments in support of the idea of natural
-    selection.]
-
-    [Illustration: Alfred Wallace, 1823-1913, was the co-originator,
-    with Darwin, of the principle of natural selection, or “survival of
-    the fittest.” The main difference between the two was that Wallace
-    did not believe that natural selection explained things as well as
-    Darwin thought it did, which has been borne out to a large extent by
-    modern studies of genetic variation. Wallace worked in South
-    America, along the Amazon and Rio Negro rivers, and in East Asia. He
-    showed that the animals on either side of a line between Borneo and
-    the Celebes Islands are radically different in their makeup and
-    origin. Now known as “Wallace’s Line,” his work has been vindicated
-    by additional modern studies. Although Wallace did not become as
-    well known as Darwin, his brilliant, independent studies lent a
-    great deal of weight to the Darwinian view of evolution.]
-
-    [Illustration: _The largest divisions of geologic time are eras,
-    shown above in chronological order from the oldest on the bottom to
-    the most recent on top. The scale at left shows the relative
-    duration of each era. As the chart shows, geologists further divide
-    time into periods and, in the Cenozoic Era, into epochs. The
-    fossilization of animals in the Agate Springs area of Nebraska took
-    place in the Miocene Epoch. Adjustments to this time chart are made
-    as new data becomes available, so it should not be thought of as an
-    unchanging reference. This diagram is adapted from one in The
-    Emergence of Man series published by Time-Life Books._]
-
-                           Geologic Time Chart
-                 Period        Epoch    Time span (years before present)
-
-  Cenozoic    Quaternary    Pleistocene              10,000 to 2 million
-              Tertiary      Pliocene                      2 to 5 million
-                            Miocene                      5 to 23 million
-                            Oligocene                   23 to 34 million
-                            Eocene                      34 to 55 million
-                            Paleocene                   55 to 65 million
-  Mesozoic    Cretaceous                               65 to 138 million
-              Jurassic                                138 to 205 million
-              Triassic                                205 to 240 million
-  Paleozoic   Permian                                 240 to 290 million
-              Carboniferous                           290 to 365 million
-              Devonian                                365 to 410 million
-              Silurian                                410 to 435 million
-              Ordovician                              435 to 500 million
-              Cambrian                                500 to 570 million
-  Precambrian                                      570 to 4,500+ million
-
-
-                     The Geologic History of Agate
-
-Although the whole story of Agate Fossil Beds dates from the formation
-of the Earth four and one half billion years ago, only the last 600
-million years is known in detail. It was about 600 million years ago
-that many plants and animals began to have hard parts—parts likely to be
-preserved as fossils. The few fossils contained in older rocks are often
-folded, twisted, squeezed, and distorted so that their original
-character is all but erased. That isn’t always the case, of course. Some
-of these old rocks, the Belt Series in Montana, look as though they were
-deposited only a few million years ago; they contain traces of algal
-colonies indicative of the generally simple life forms on the primitive
-Earth. The old rocks, deposited during the first four billion years of
-Earth’s history, record the Precambrian Eons, spanning eight-ninths of
-geologic time.
-
-The evolutionary development of skeletal remains has aided in the study
-of geologic history. The last 600 million years have been divided into
-units for ease of discussion and comparison. The three largest divisions
-are the eras—Paleozoic (ancient life), Mesozoic (middle life), and
-Cenozoic (recent life). We are viewing all this from our vantage point
-at (what is now) the most recent episode of the Cenozoic.
-
-To begin at the known beginning, we only need go back to the start of
-the Paleozoic Era some 600 million years ago. No Precambrian, Paleozoic,
-or Mesozoic rocks can be seen around Agate, but we know from rocks found
-in comparable areas about what to expect under the surface at Agate:
-thousands of meters of sedimentary rocks, most of them laid down in an
-ocean. During the Paleozoic and most of the Mesozoic eras, up until
-about 70 million years ago, the west-central United States was covered
-by seas. The area now occupied by the Rocky Mountains was then a long
-north-south trough in which thick sediments collected. To the east, the
-present Great Plains area was the floor of a shallower sea. Sediments
-collected in the trough and on the sea bottom. Gradually, over a period
-of 530 million years, the sediments accumulated to a thickness of over
-2,100 meters (6,900 feet). A dynamic “give-and-take” process, this
-sedimentation was the result of periods when the sea rose and fell
-several times.
-
-If the Paleozoic sounds a little dull, it’s because we haven’t told the
-whole story. During the Paleozoic Era, all the major groups of organisms
-evolved. The seas swarmed with trilobites and shellfish of all kinds,
-some weird and fantastic and some very like those alive today. With them
-coexisted fish and sea-lilies, seaweeds and giant swimming “scorpions.”
-For the first time, plants and then animals came out of the sea to live
-on the land. These events and creatures are preserved in Paleozoic
-rocks. The Mesozoic Era saw the development of mammals from reptiles,
-the rule of giant dinosaurs, and the beginnings of flight. Strange
-reptiles evolved and returned to the sea, or glided through the air on
-motionless wings. The Sundance Formation, deposited in the northern
-Rocky Mountains about the middle of the Mesozoic Era, is noted for the
-masses of bullet-shaped squid shells found in it. Water, land, and air
-were full of life.
-
-In the Middle Mesozoic, the trough drained and much of it became an area
-of swamp and tropical forest extending from Montana to southern Utah.
-This was the domain of our largest dinosaurs, giant reptiles whose bones
-were preserved in impressive numbers. Como Bluff and Bone Cabin,
-Wyoming; Morrison, Colorado; and Dinosaur National Monument and
-Cleveland, Utah, are the sites of quarries where many fine specimens of
-_Apatosaurus_, _Diplodocus_, _Stegosaurus_, and _Allosaurus_ have been
-collected. These caches of bones have made our large museums showplaces
-known throughout the world.
-
-During the last 65 million years of the Mesozoic, the trough fluctuated
-up and down. During much of that time a broad, shallow sea covered
-central North America from the Gulf of Mexico to the Arctic Ocean. The
-sea was filled with fish like the giant _Portheus_ (3.5 meters/11.5 feet
-long), with squid-like animals floating about in elaborate chambered
-shells, and with reptiles which had gone back to the water. Where there
-was a broad coastal plain, it swarmed with dinosaurs, the ones that make
-Lance Creek, Wyoming and Hell Creek, Montana famous collecting grounds
-for museum field parties. Yet at the end of the era the trough was a
-seaway again, and in the Agate area a final blanket of black mud, the
-Pierre Shale, was deposited in the sea.
-
-At the end of the Mesozoic Era a profound change came over the land. The
-trough, with hundreds of meters of sediments accumulated on its bottom,
-was drained and folded by pressures built up in the Earth’s crust. To
-the south, the Colorado Plateau rose slowly and smoothly; to the north
-folding and faulting built complex mountain ranges. This uplift is
-called the Laramide Revolution because of the magnitude of the change it
-made on the face of the continent.
-
-At the beginning of the Cenozoic Era, about 65 million years ago, the
-Rockies and the Great Plains were slowly rising. Rains fell and rivers
-carried the water, wearing away the old sediments. Some sediments were
-carried west into the Pacific Ocean, or deposited on the land and
-covered over by new sediments. Some sediments remained within the
-Rockies, settling into basins during the early Cenozoic. Other sediments
-were carried east by the rivers, beyond the Great Plains and into the
-Mississippi Embayment. Mountain building and erosion tended to cancel
-out one another in the Rockies, preventing the mountains from reaching
-great heights. The mountain bases were perhaps no more than 300 meters
-(1,000 feet) above sea level, and the crests perhaps 600 meters (2,000
-feet) above that.
-
-Before long, the basins within the Rockies filled with sediments. The
-basins overflowed, and at last sediments began to cover the Great
-Plains. This was near the end of the Eocene Epoch, about 35 million
-years ago. Subtropical rivers, flowing sluggishly, rolled out over their
-banks and left their loads of silt and clay on the featureless plain.
-
-The oldest part of the blanket of sediments, the White River Beds,
-extended from Saskatchewan to Texas. Nearly 200 meters (650 feet) of
-muds, clays, silts, and river gravels were laid down during the 11
-million years of the Late Eocene and Oligocene Epochs. Magnificent
-exposures of these beds can be seen at Scotts Bluff National Monument in
-the valley of the North Platte, in Toadstool Park north of Crawford,
-Nebraska, and particularly in the Big Badlands of southwestern South
-Dakota.
-
-The kind of floodplain deposition characteristic of the Oligocene on the
-Great Plains ended about the beginning of the next epoch, the Miocene.
-In Nebraska the process continued, but eventually erosion began wearing
-away the accumulated sediments. The land to the west was uplifted a
-little, and the streams flowed off the high ground fast enough to cut
-down into what they had just deposited. On this eroded surface, the
-layers of tan silts, fine sands, and clays known as the Gering Formation
-were deposited.
-
-On top of the Gering Formation, in the Late Oligocene, is the Monroe
-Creek Formation, the oldest formation actually exposed in the Agate
-area. This formation is named for exposures in Monroe Creek Canyon north
-of Harrison, Nebraska, and may be up to 75 meters (245 feet) thick. You
-can see a little of the Monroe Creek Formation’s pinkish silts and
-volcanic glass shards exposed in the valley of the Niobrara River. Where
-it is more exposed by erosion than at Agate, the Monroe Creek Formation
-forms magnificent cliffs along the Pine Ridge and similar areas of high
-ground. The best local examples are at Fort Robinson State Park between
-Harrison and Crawford, Nebraska. A close look can be obtained in Smiley
-Canyon just west of the fort, where old U.S. Highway 20 is maintained as
-a scenic drive.
-
-After the Monroe Creek interval, near the end of the Oligocene,
-deposition of the famous Agate Fossil Beds began. Geologists have named
-this sequence of grayish silts and sands the Harrison Formation for its
-occurrence near Harrison, Nebraska. A short interval of erosion
-separates it in some areas from the Monroe Creek Formation below, and
-its coarser sands indicate increasing uplift of lands to the west. Wind
-played a smaller role in deposition than in Monroe Creek times, though
-that is certainly not true at the _Stenomylus_ quarry. The Harrison
-Formation was the last of the truly widespread deposits seen in the
-Miocene of the Great Plains. Many rivers flowing eastward from the
-Rockies contributed sands to Wyoming, South Dakota, and Nebraska.
-
-Generally the Harrison Formation and the overlying Marsland Formation
-are only moderately fossiliferous, but along the Niobrara River here at
-Agate, Nebraska, the accumulation of rhinoceros and camel skeletons is
-one of the wonders of the fossil world. Here, thousands of animals
-perished in two droughts which coincided with conditions perfect for
-preservation. About two kilometers (1.2 miles) east of the Monument
-headquarters the dried-out, mummified bodies of perhaps a hundred or
-more little camels, _Stenomylus hitchcocki_, were buried under windblown
-sand during the first drought.
-
-Shortly after the camels were buried there was a brief period of erosion
-and then the Marsland Formation began to be deposited. Named for a
-little village east of Agate, the Marsland Formation consists of basal
-river channel deposits followed by about 45 meters (150 feet) of
-wind-blown tan-and-gray sands. It is in one of these river channel
-deposits that the Agate rhinoceros quarries are located.
-
-The second drought occurred early in Marsland times and literally
-hundreds of the little rhino, _Menoceras_, were preserved when their
-carcasses were broken up by a reborn river and buried like a mat of
-jackstraws in a river lake.
-
-After Marsland times there was more erosion, in some places by rushing
-streams that cut down 91 meters (300 feet) through soft sediments, to
-the top of the Monroe Creek Formation. In these channels the
-Runningwater Formation was deposited because it filled in the stream
-valleys and wound around the high spots. This channel deposit is not
-found everywhere, but it does have an equivalent in southwestern South
-Dakota. Other deposits of similar age are found in many parts of the
-Great Plains, and they contain fossil animals like those found in the
-Runningwater Formation.
-
-The turbulent streams which deposited the Runningwater Formation were
-flowing off newly uplifted land to the west. This was the beginning of
-the most recent major uplift of the Rocky Mountains, and it signalled a
-great change in the pattern of deposition on the Great Plains. No longer
-would broad blankets of sediments be deposited by sluggish streams
-originating in the low, broad warp of the Rockies.
-
-This latest uplift is called the Rocky Mountain Revolution. It brought
-on a period of alternating cycles of deep channel cutting and stream
-deposition. Floodplain deposits were restricted to narrow ribbons in
-river-cut valleys. Even more important than the changes in deposition
-was the effect of this uplift on the climate. As the Rockies began to
-rise to their present height, the climate became increasingly arid and
-the tree-dotted savanna of the old Great Plains gave way to grasslands.
-
-Several kilometers south of Agate, the Sheep Creek Formation was laid
-down during the Middle and Late Miocene. The appearance of the grazing
-horse _Merychippus_ in these channel and floodplain deposits marked the
-establishment of the grasslands as the newly dominant ecosystem of the
-Great Plains. At that time the “modern” fauna began to replace the old,
-and new patterns of life were established.
-
-Again rejuvenation of the stream system, probably reflecting further
-uplift in the west, started another erosional interval that began to
-wash away the beds just deposited. When deposition followed in the Late
-Miocene, a new series of channel and floodplain deposits, the Lower
-Snake Creek Beds, was laid down. On them was deposited the Upper Snake
-Creek Beds, and together they span most of the Late Miocene and the
-Early and Middle Pliocene epochs. Harold Cook collaborated with W. D.
-Matthew of the American Museum of Natural History, publishing important
-papers on the numerous finds from these fossiliferous deposits. Animals
-new to science are still being discovered in the Snake Creek Beds.
-
-After Snake Creek times, the area immediately around Agate was left out
-of the mainstream of events on the Great Plains. The continuing uplifts
-of the Rocky Mountains were no longer recorded here in cycles of
-downcutting and channel deposition. If the cycles continued here, all
-traces have now been washed away—an unlikely possibility. The view from
-the high plains above the valley of the Niobrara River reveals only the
-rolling surface of the pre-Runningwater deposits.
-
-A more complete record is found in the river terraces of major streams,
-the North Platte to the south and the White and Cheyenne Rivers to the
-north. These terraces tell the story of continuing uplifts. To the
-south, east, and northeast of the Platte the record is also written in
-fossil bones, but these are outside the scope of our story.
-
-Northwestern Nebraska, northeastern Colorado, southeastern Wyoming, and
-southwestern South Dakota today remain a promised land for
-paleontologists studying mammal life in North America during the middle
-and later Cenozoic Era. The fossil deposits in the Agate area are
-surpassed in importance only by the Late Eocene and Oligocene deposits
-of the Big Badlands and Pine Ridge in South Dakota.
-
-
-                     Ecology: Change and Adaptation
-
-During the Age of Mammals (the Tertiary Period), three major
-environments dominated western Nebraska. The first of these occurred
-during the Paleocene, Eocene, and Oligocene epochs. This was a forest
-system where trees were the major component of the flora. Meadows were
-found only in scattered areas and can be considered a minor element.
-There is no geologic or paleontologic record of the Paleocene and Eocene
-in the Agate area, but when our present knowledge of the early Tertiary
-Rocky Mountain floras is projected eastward a bit, a predominantly
-forested landscape is indicated.
-
-It is in some ways ironic that while the Oligocene land-laid sediments
-of southwestern South Dakota, western Nebraska, southeastern Wyoming,
-and northeastern Colorado contain one of the best vertebrate fossil
-records in the world, the plant record is almost non-existent.
-Unfortunately the groundwater chemistry that was so right for the
-preservation of bones was hostile to the preservation of plants.
-Hackberries (_Celtis_) and walnuts (_Juglans_) are the only recorded
-plant species from the Oligocene in this very large area. Because these
-are such widespread and climatically tolerant types, they tell us almost
-nothing about the environment. Indications of the flora at Agate may be
-obtained, however, from the extraordinary Late Eocene flora found at
-Florissant, Colorado, south of Denver. Although this deposit does
-contain some upland species, it generally indicates a warm temperate
-forest including such things as horsetail rushes, ferns, cattails,
-grasses and sedges, poplar, willow, birch, oak, elm, serviceberry,
-sycamore, maple, sumac, and—of course—hackberries and walnuts.
-
-During the Early Miocene, slightly changed climatic conditions brought
-about by minor uplifts in the Rocky Mountain area transformed the
-immediate area of western Nebraska into a savanna of mixed trees and
-grasslands. This second system probably reached its climax just about
-the time the Harrison Formation was being laid down during the Early
-Miocene. This was a savanna with scattered clumps of trees, gallery
-forests, and grasslands. The modern world’s richest and most diverse
-fauna of hoofed mammals can be found on the savannas of east Africa. On
-the savannas, grazing and browsing (grass eating and leaf eating)
-adaptations of the larger plant eaters are represented.
-
-    [Illustration: 35 million years ago]
-
-    [Illustration: 25 million years ago]
-
-    [Illustration: 15 million years ago]
-
-    [Illustration: 35 million years ago, life along the Niobrara River
-    near Agate would have appeared something like this. Two oreodons (1)
-    have startled an alligator (2) and two hippopotamus-like
-    _Aepinacodons_ (3) along the river bank. Climbing a tree is an
-    opossum (4), one of the oldest forms of life in the world today.
-    Note the many familiar trees and plants, particularly the
-    cottonwood, willow, beech, dogwood, and cattail.]
-
-    [Illustration: 25 million years ago, a savanna dominates the Agate
-    landscape. Copses of oak and pine are interspersed with open
-    grassland. In the foreground are several _Parahippus_ (1), an
-    ancestor of today’s horse, while _Oxydactylus_ camelids (2) move
-    away into the distance and, overhead, a hawk (3) searches for
-    rodents.]
-
-    [Illustration: 15 million years ago, the Agate landscape has changed
-    to an open prairie. A small herd of _Merychippus_ horses (1) races
-    toward the arroyo in the distance, narrowly escaping ambush by a
-    large, leopard-like cat known as _Pseudaelurus_ (2). A few
-    cottonwoods, elms, sycamores, and willows grow along the river, but
-    cedars predominate in the arroyo in the middle ground, where they
-    are protected from winds that sweep across the plains. Though the
-    animals have changed, the landscape is essentially like this today.]
-
-In western Nebraska the savanna environment lasted for only a very short
-time, in a geologic sense, before it gave way to a wave of advancing
-grasslands, the third phase of Tertiary environment in the area.
-Tallgrass prairie such as that still found 325 kilometers (200 miles)
-east of Agate a century ago must have been first among the grassland
-types. Trees, when present at all, were restricted to the borders of
-streams. Then as the climate became even more arid the prairie or tall
-grass retreated eastward, while the forest moved before it even farther
-to the east and south, and the modern shortgrass of the plains took its
-place. Today Agate lies in one of the valleys whose rivers are slowly
-dissecting the High Plains.
-
-The modern plains are dominated by short, curly, sodforming buffalo
-grass, a plant well adapted to the area’s light rainfall, periodic
-droughts, low humidity, rapid evaporation, and high winds. The dominant
-vertebrate animals are burrowers and grazers, and dogs are the primary
-carnivores. Hoofed animals such as the pronghorn, the ultimate in the
-running and bounding adaptation; jumpers and hoppers, such as
-jackrabbits and jumping mice and rats; and burrowing mound builders,
-such as the prairie dog (a large ground squirrel), the pocket gopher,
-and harvester ants typify the major occupations of plains animals.
-
-The environmental type seen on the Great Plains of North America is
-elsewhere best developed in the Pampas of Argentina, the Puztas of
-Hungary, the Veld of Africa, and the Steppes of Russia. In the climatic
-classification of the climatologist and geographer, the term _steppe
-climate_ is applied to all these areas, the Great Plains included.
-
-If the savanna is the halfway station between forests and grasslands,
-then the fossil fauna of the Early Miocene at Agate was a fauna in the
-beginning of a serious transition. In the vicinity of Agate, the fauna
-from the Late Oligocene was dominated by mammals with low-crowned teeth.
-The crown is that part of the tooth which is above the roots and exposed
-beyond the gums. Among the herbivores, the browsers can live a long life
-with low-crowned teeth. But when any appreciable amount of grass,
-particularly the short, tough grass of the plains and the abrasive dirt
-and sand that accompanies it, becomes part of an herbivore’s diet, there
-is a great increase in the rate of tooth wear. Teeth which have evolved
-for browsing quickly wear down to the gums and the individual dies of
-starvation.
-
-Accompanying the development of extensive grasslands came the evolution
-of the high-crowned tooth. This process begins simply with the growth of
-a taller crown that erupts completely from the gum right after the milk
-or deciduous teeth fall out. Another step is the development of a longer
-or higher crown most of which is held in the jaw and then slowly pushed
-out as the chewing surface is worn down. This is the “mechanical pencil”
-effect in that the “lead” may be pushed out as needed. Teeth of this
-type are perhaps best seen in the later horses. From their appearance in
-the Late Paleocene until the end of the Early Miocene, all horses had
-low-crowned teeth. With these they could chew the soft leaves and twigs
-of trees and shrubs, first in the forests and later in the groves and
-clumps on the developing savanna. By Early Miocene (i.e., Harrison)
-times, there was only a slight increase in crown height in _Parahippus_,
-but it had evolved an increasingly complicated crown pattern which
-served to lengthen the time it took for the tooth surface to wear down
-flat. With the greater aridity of the changing climate, the teeth of
-_Parahippus_ became higher and higher crowned, as the individuals with
-the best teeth lived longest and had greater opportunity to produce
-offspring than those with lower-crowned teeth. In some species, the
-tooth material called cement, which ordinarily covers the roots of the
-teeth, began also to cover the enamel of the crown and give additional
-wearing strength to the teeth. Soon after the beginning of the Middle
-Miocene, two species had developed cement-covered teeth whose crowns
-were high enough to warrant placing them into two new genera of horses,
-_Merychippus_ and _Protohippus_. These forms, first recognized in the
-Lower Sheep Creek Beds in the Agate area, were the first horses to use
-the mechanical-pencil effect, having cheek teeth that continued to rise
-out of the jaw as the tooth was worn down. _Merychippus_ later gave rise
-to a line of three-toed horses, which lived on into the Pliocene;
-_Protohippus_ gave rise to a line which ultimately led to _Equus_, the
-modern horse.
-
-The ultimate in high-crowned teeth occurs when roots do not ever form at
-the base of the tooth; additional crown material is constantly added at
-the bottom of the tooth as it is pushed out of the gum. This type of
-growth resembles the foundry process of extrusion, where metal or
-plastic is pushed through a mold to produce a continuous strand. This
-extreme development is seen in the incisors or gnawing teeth of beavers,
-gophers, and other Late Oligocene rodents, and in the grinding teeth of
-only a few forms. The cheek teeth (the grinders) of modern pronghorns
-(artiodactyls), gophers (rodents), and rabbits (lagomorphs) are typical
-of this kind of development today. During the Middle Oligocene, only the
-strange little fox terrier-sized, flat-headed oreodon _Leptauchenia_,
-the tiny “deer” _Hypisodus_, and the rabbit _Palaeolagus_ had mechanical
-pencil-type teeth. Some of the rhinos then had fairly tall crowns, but
-these don’t really qualify as high-crowned teeth. It was not until later
-on, when the grasslands took over completely, that high-crowned teeth
-really came into their own.
-
-There was no dramatic change in the fauna at the beginning of the
-Miocene, and many Oligocene genera carried over into the new epoch. Most
-of the Eocene hold-overs, primitive animals that had survived in the
-extensive forests, became extinct when the forests began to retreat; but
-for the most part the record continued undisturbed. This is to be
-expected where the deposition of sediments continues without
-interruption. (Remember that the epochs, periods, and eras were
-originally based on breaks in the European sedimentary record reflecting
-local events which would not necessarily show up in North America’s
-sediments.)
-
-By the time the Harrison Formation was deposited, the development of the
-halfway world of the savanna was beginning to affect the fauna. Although
-the Oligocene and the very earliest Miocene mammal faunas were highly
-varied and rich in types of animals, much of this was due to the
-continued presence of primitive and archaic forms, and to the explosive
-development of rhinos and oreodons. With the savanna becoming the
-dominant landscape, the shift to grazing and away from browsing became
-evident. Or, at least, the presence of animals that both browsed and
-grazed was indicative of changing times. As was mentioned earlier,
-grazing and burrowing are characteristics of plains herbivores. In such
-a transitional period we would expect to find an increase in burrowers
-and grazers as grasslands became more common.
-
-
-                          Evolutionary Change
-
-  Animal species respond to environmental changes in a variety of ways.
-  Simply put, some species die off, some adapt physically, and some move
-  to a different habitat. On the next few pages are examples showing how
-  three species responded to long-term environmental changes in the area
-  around Agate Fossil Beds. The _Stenomylus_ line died off; _Miohippus’_
-  evolutionary line remained a grazing animal but changed physically
-  over the years, eventually becoming the modern horse; and the
-  _Palaeocastor_ line moved from land to water, gradually evolving into
-  the beaver.
-
-  Each of these three animals is portrayed here with partial skeleton,
-  musculature, and outer skin to help you see its general composition
-  and to emphasize certain physical features that developed in the
-  species over time. Paleontologists, of course, work this way. From
-  fragments and bones they reconstruct full skeletons, and from surmises
-  about muscular structure, often based on present-day animals, they
-  project the appearance of the animal. The artist, in this case Jay
-  Matternes, then brings together these bits of evidence to give us a
-  picture of life long ago.
-
-
-                                  Stenomylus
-
-A small, gazelle-like camel similar to the present-day gerenuk of
-  Africa. _Stenomylus_ is the second most common animal found in the
-  fossil beds at Agate. _Stenomylus_ had hard hooves like modern
-  antelopes and deer, unlike modern camels which have flesh-padded feet
-  adapted to desert terrain. The three-hued coat is inferred from the
-  coat of the modern gazelle, a similar form in adaptation.
-  _Stenomylus’_ evolutionary line eventually died out in North America
-  at the end of the Pleistocene. No one knows why both camels and horses
-  died out on this continent.
-
-            The distance between grid lines represents five centimeters.
-
-    [Illustration: 1 The ears moved in a parallel fashion, not
-    independently; the parallel movement is inferred from modern
-    llamoids, to which _Stenomylus_ is related.
-
-    2 _Stenomylus’_ musculature was adapted for high-speed running,
-    similar to the present-day pronghorn.
-
-    3 The back structure suggests that _Stenomylus_ would have made
-    short, choppy leaps, not the graceful, arcing leaps of a modern
-    impala.
-
-    4 Limbs were long in proportion to the body, allowing the animal to
-    run with great speed.
-
-    5 _Stenomylus_ had a hard, chitinous hoof, an adaptation for greater
-    running speed, and for sure footing on rough terrain.]
-
-
-                               Miohippus
-
-Over the last 60 million years the horses have evolved from small,
-terrier-sized animals to the diversity of size we know today, from the
-huge Clydesdales to the diminutive Shetland ponies. The three-toed early
-horse known as _Miohippus_ was about the size of a sheep. The
-descendants of _Miohippus_ apparently went in two directions in their
-evolution: One group continued to be forest-grazing, three-toed horses
-that eventually reached the size of modern horses but died out later.
-The other group, through such intermediate forms as _Parahippus_, became
-grassland forms that led eventually to the modern one-toed horses.
-Horses became extinct in North America at the end of the Pleistocene,
-but no one knows why. They continued to evolve on other continents and
-were re-introduced in historic times.
-
-            The distance between grid lines represents five centimeters.
-
-    [Illustration: 1 The back was straighter and stiffer than in earlier
-    horses, partly because of the increasing size of the animals and
-    partly to allow sustained open-plains running.
-
-    2 Limbs were long in proportion to the body, an evolutionary trend
-    in the horses for speed in open-plains running, rather than darting
-    about in forests.
-
-    3 Most of the weight of the animal was on the middle toe, which has
-    become a single toe in modern horses. This is an adaptation for
-    endurance and stability in open grasslands.
-
-    4 The upright mane is a primitive horse characteristic; wild horses
-    today have reverted to this trait.
-
-    5 The coat is shown as striped, a probable holdover from earlier
-    horses that dwelled in forests, where a striped coat would provide
-    camouflage.
-
-    6 A large, deep mandible supported teeth adapted to grazing and the
-    grinding of grasses and other wild plants. The teeth were
-    deep-rooted and continuously erupted as the surface was worn down by
-    the grit and dirt that came with the large quantities of plant food
-    consumed daily.]
-
-
-                              Palaeocastor
-
-_Palaeocastor_ was an ancient beaver whose mode of life was like that of
-a modern prairie dog—land-oriented instead of water-oriented.
-_Palaeocastor_ was small, about 12 centimeters (5 inches) high, and
-about 30 centimeters (12 inches) long. Its fossilized spiral burrows,
-called _Daemonelix_, survive to tell us what its habitation was like, a
-feature unique to _Palaeocastor_ among all the fossil beavers. The
-_Daemonelix_ shown here dwarfs a member of Olaf A. Peterson’s field crew
-from the Carnegie Museum. The bones of a _Palaeocastor_ and one of its
-predators were found at the bottom of one such burrow, helping to prove
-that _Palaeocastor_ was responsible for making these corkscrew holes in
-the ground.
-
-            The distance between grid lines represents five centimeters.
-
-    [Illustration: 1 The powerful jaw and musculature allowed for
-    grazing on grasses and other plants, as well as masticating. The
-    teeth were deep-rooted and would continue to erupt as the surface
-    was worn down.
-
-    2 The complex musculature supported the use of the forelimbs in
-    burrowing. _Palaeocastor_ had a collarbone or clavicle, like us, for
-    greater agility in using the forelimbs.
-
-    3 The forelimbs were adapted to burrowing in the ground.
-
-    4 The tail is like that of a modern burrowing rodent, such as a
-    muskrat, whereas the modern beaver has a different, very specialized
-    tail.]
-
-    [Illustration: Daemonelix]
-
-A grazing animal is fairly easy to recognize, but how can we recognize a
-burrower? Some have radically adapted limbs and claws. Obvious cases are
-the common garden mole and the armadillo. The mole has powerful
-attachments for the muscles of the upper arm on the humerus, a bone so
-flattened that its width has come to match its length. Moles also have
-long, broad digging claws. The armadillo, which is also a digger but not
-a burrower in the same way a mole or a gopher is, has large curved claws
-for digging. Moles did start to become quite common in the Late
-Oligocene, so we can assume that a good burrowing environment was
-present.
-
-Another group which became extraordinarily common in the Late Oligocene
-of western North America was that of the ancestral pocket gopher. Direct
-proof that this group actually burrowed does not exist, but the
-abundance of fossil gophers suggests that they might have lived
-underground in colonies.
-
-A real surprise at Agate is the number of beaver burrows. The famous
-_Daemonelix_ or “devil’s corkscrew” attests to the dense population of
-_Palaeocastor_. By that relatively advanced stage of beaver evolution,
-the animals might be expected to behave like the modern-day muskrat,
-perhaps digging dens along stream borders and spending some of their
-time in the water. The presence of skeletons in the spiral burrows,
-however, indicates that _Palaeocastor_ was primarily a burrower, one
-which perhaps lived very much like our present-day prairie dog. Despite
-that, there is no apparent structural modification to indicate burrowing
-abilities.
-
-Changing environmental conditions were pushing _Palaeocastor_ toward
-extinction in the Early Miocene. The disappearance of that ancient
-beaver, while not unusual, presents a problem for the careless observer
-who might assume that ancient animals behaved like their modern
-counterparts. The burrowing beavers of Miocene Agate certainly have no
-modern counterparts.
-
-While we can delineate in a general way the prehistoric life of Agate,
-we can’t describe the past in any detail. Plants most directly reflect
-the effects of climate—and plant fossils are absent at Agate. As the
-base of the food chain, plants carry the influences of climate on to the
-plant-eating animals. From the numerous animal fossils found at Agate we
-have learned most of what is known about the environment of that time.
-Sediments tell a good part of the story, and floras from other
-localities help, but much of Agate’s ancient ecology must be inferred
-from the bones.
-
-Today, standing on the porch of the visitor center or walking along the
-path to University and Carnegie Hills, visitors find themselves in the
-midst of the shortgrass prairie. Five distinctive plant communities
-share this prairie, coexisting in a dynamic relationship which depends
-upon local climate variations.
-
-Even to the untrained eye, it is evident that the basic short-grass
-pattern has been modified by the shape of the land and by the Niobrara
-River. In the stream valley, along the tributaries, and on shaded
-north-facing slopes, the shortgrass community is mixed with taller
-grasses. If a dry cycle began, the short grasses would take over the
-whole area by migrating downslope from the exposed prairies. Of interest
-is the fact that over-grazing by either domesticated or wild animals
-will have the same effect as a dry period in that taller grasses will be
-replaced by short ones.
-
-Let’s examine the five communities present today so we can appreciate
-the complexity of relationships between living things and the earth upon
-which they depend.
-
-First, we can begin in the Niobrara River itself. The river’s
-water-dwelling plant inhabitants include algae, which grow underwater.
-
-Between the river and the dry ground is a second community—the
-marsh—which is often more wet than dry. The marsh has its own
-characteristic plant association. Most familiar are the cattails, mints,
-and willows, but just as important ecologically are arrowleaf, rush
-sedge, marshweed and blue verbena. These are moisture-loving plants that
-thrive on being thoroughly soaked during the wet part of the year.
-
-Beyond the marsh on the valley floor is a third community. Here the
-water table (the top of the saturated soil and rock zone) is close
-enough to land surface that the plants can easily send their roots down
-into the saturated zone. Here, in what the plant ecologists call the
-“sub-irrigated floor plain” we find a mid-grass community. Eighty-five
-percent of the vegetation is slender wheatgrass. Its wheat-like heads
-may, under favorable conditions, grow to a height of one meter (three
-feet). At Agate it is seldom over knee high. Kentucky bluegrass takes
-care of another 10 percent of the plant population. Imported from Europe
-as a pasture grass in the 1600’s, it spread so rapidly that it often
-beat the settlers onto new land as they moved westward. The remaining
-five percent includes imported redtop and such native grasses as
-switchgrass, foxtail barley, little bluestem, prairie cordgrass, and
-inland saltgrass. Wildflowers such as Flodmon thistle, yarrow, heath
-aster, salsify, and blue-eyed grass complete the community.
-
-Moving farther away from the stream, we rise up onto terraces within the
-valley. These terraces represent levels where the stream paused in its
-downcutting and cut sideways for awhile. At a drier level, on deep,
-well-drained sandy soils, they support the fourth or mixed-grass
-community.
-
-No exotics have yet appeared in this plant community. The grasses
-include prairie sandreed, sand bluestem, blue grama, needle-and-thread
-grass, and Indian ricegrass. Wildflowers include the prominent phlox,
-penstemon, and lupine. Unwelcome (to man and his grazing animals) is
-_Astragalus_, the selenium-concentrating plant better known as loco
-weed. The brittle prickly pear and spiderwort cactus are found here too.
-
-At higher levels in the terrace community, slightly steeper slopes and
-shallower soils cause some change in this mixed-grass assemblage. Here
-the dominant grasses are little bluestem, threadleaf sedge,
-needle-and-thread grass, and blue grama. Lupine disappears, and common
-pricklypear becomes the only cactus. In this community is found the
-yucca, its flowers a beautiful soft yellow in season and its spiny
-leaves painful at any time of the year. Avoid this plant; yucca spines
-break off under the skin and soon cause irritating festers. The yucca
-moth, often seen flying around the yucca seed pods, lays eggs in the
-plant’s lemon-sized fruits. Inside the fruit are long rows of flattened,
-wedge-shaped seeds. When the yucca moth eggs hatch into caterpillars,
-they eat their way through the seeds, killing them. On the other hand it
-is the yucca moth with its long tongue that is solely responsible for
-pollinating the yucca flower! If you find a yucca fruit in early summer,
-you can (elsewhere than in the park) slice through it and see the
-caterpillars at work.
-
-On the high bluffs and overgrazed terraces is the fifth community, the
-short grass. This community too can be divided into two slightly
-different parts. The bluffs support blue grama grass, needle-and-thread
-grass, and Sandberg blue grass. Flowers and shrubs include _Eriogonum_,
-brittle pricklypear cactus, pepperweed, penstemon, broom snakeweed,
-fringed sagewort, and yucca. The other part of this community, the
-overgrazed terraces, have threadleaf sedge, needle-and-thread grass, and
-blue grama. Except for the familiar penstemon, all the flowers are
-restricted to this community. Gronwell, menzania, and bee plant are
-indicators of overgrazing.
-
-Certain cyclical variations are characteristic of these plant
-communities. First, the shortgrass and mixed-grass areas ebb and flow
-with changing moisture conditions from year to year. Second, grass
-populations change with the seasons. Cool-season grasses (foxtail
-barley, Indian rice grass, Kentucky bluegrass, needle-and-thread grass,
-Sandberg blue grass, and slender wheatgrass) flourish during spring and
-fall. During the warm summer the blue grama, inland saltgrass, little
-bluestem, prairie cordgrass, prairie sandreed, and switchgrass
-predominate. This natural adaptation to seasonal conditions uses the
-greatest potential of the growing season and at the same time provides
-species that will flourish in both wet and dry cycles.
-
-After reading this last section, you might look back at the section on
-Early Miocene ecology. Comparison reveals that a great deal of
-information can be obtained by examining living plants. In contrast, the
-lack of fossil flora from the Early Miocene at Agate has resulted in a
-scarcity of ecological information from that early epoch. Scientists
-begin their reasoning by such comparisons; you can begin your own
-exploration of the past in the same way.
-
-
-
-
-                         3    Guide and Adviser
-
-
-    [Illustration: Ask a ranger for directions to the protected example
-    of a Devil’s Corkscrew, the fossilized burrow of a small,
-    beaver-like animal called _Palaeocastor_. See pages 68-69 for more
-    information about this interesting animal.]
-
-
-                           Visiting the Park
-
-
-                        Contents of This Section
-
-  Visiting the Park                                                    77
-      Location
-      Area
-      Climate
-      When to Visit
-      Visitor Center
-      Activities
-      Camping
-      Nearby Accommodations
-      Transportation
-      Establishment Date
-      Address
-      Access
-  Protection                                                           80
-      Park Regulations
-      Safety Tips
-  Birding Along the Niobrara                                           81
-      Taking the Annual Count
-  Collections of Agate Springs Fossils                                 86
-  NPS Areas With Fossil Exhibits                                       88
-      Badlands
-      Dinosaur
-      Florissant
-      Fossil Butte
-      Petrified Forest
-      John Day
-      Hagerman
-  Nearby National Parks                                                90
-      Badlands
-      Devils Tower
-      Fort Laramie
-      Jewel Cave
-      Mount Rushmore
-      Scotts Bluff
-      Wind Cave
-  Not So Nearby National Parks                                         92
-      Bighorn Canyon
-      Little Bighorn
-      Rocky Mountain
-      Theodore Roosevelt
-  Armchair Explorations                                                93
-
-
-                                   Location
-
-Northwestern Nebraska 69 kilometers (43 miles) north of Scottsbluff
-along the Niobrara River.
-
-
-                                  Area
-
-1,116 hectares (2,762 acres).
-
-
-                                Climate
-
-Temperatures range from winter lows of -38° C (-36° F) to summer highs
-of 39° C (101° F). Winter temperatures average 1° C (33° F), and winter
-snow averages 60 centimeters (2 feet) for the whole winter. However,
-snowdrifts can be much higher. Summer nights are cool, with temperatures
-averaging 10° C (50° F). Average annual precipitation is 41 centimeters
-(16 inches), with most precipitation in April and May.
-
-
-                             When to Visit
-
-Most people go to the park some time between June and August, but you
-can avoid the high summer temperatures by visiting in the spring, fall
-or—if you don’t mind the cold and snow—in the winter. Spring can be
-blustery, but the fall is usually dry and the days are cool. Check ahead
-on local weather conditions if you plan a winter visit. Museums and
-tourist attractions in nearby Fort Robinson are open Memorial Day to
-Labor Day.
-
-
-                             Visitor Center
-
-A ranger is on duty to help you and answer your questions. Fossil
-exhibits and part of James H. Cook’s personal collection of Indian items
-are on display in the visitor center, and publications about the park,
-paleontology, and history are on sale.
-
-
-                               Activities
-
-A trail from the visitor center takes you on a tour to both University
-and Carnegie Hills, with an interpretive display at each. The roundtrip
-distance is three kilometers (two miles) and takes about one hour. You
-may fish for German brown and rainbow trout in the Niobrara River if you
-have a Nebraska fishing license. The park has several tables for
-picnickers.
-
-
-                                Camping
-
-The park has no camping facilities, but there are state campgrounds near
-Harrison and near Fort Robinson, Nebraska, and a commercial campground
-on Nebr. 26 between Mitchell and Scottsbluff, Nebraska.
-
-
-                         Nearby Accommodations
-
-Hotels, motels, food stores, outdoor supply stores, and restaurants are
-available in Scottsbluff, Nebraska. A motel, restaurant, gas station,
-and grocery store are in Mitchell, Nebraska, 55 kilometers (34 miles)
-south of the park. There are a motel, food store, drugstore, and
-restaurant in Harrison, Nebraska, 37 kilometers (23 miles) north of the
-park, and there are motels and restaurants at Fort Robinson, Nebraska,
-37 kilometers (23 miles) east of Harrison, or 74 kilometers (46 miles)
-northeast of the park.
-
-
-                             Transportation
-
-Buses—The nearest bus connections are in Scottsbluff, Nebraska.
-Airport—Scottsbluff, Nebraska, has an airport served by a scheduled
-commercial airline. Rentals—Cars may be rented at the airport or at car
-rental agencies in Scottsbluff.
-
-
-                       Establishment of the park
-
-June 5, 1965.
-
-
-                            Mailing Address
-
-
-  Agate Fossil Beds
-  National Monument, 301 River Road,
-  Harrison, NE 69346.
-
-
-                                 Access
-
-    [Illustration: To reach the park from Scottsbluff, Nebraska, take
-    Nebr. 26 west to Mitchell, then Nebr. 29 north to the park. From
-    Fort Robinson, Nebraska, take Nebr. 20 west to Harrison, then Nebr.
-    29 south to the park.]
-
-                     [Illustration: Plains states]
-
-
-                               Protection
-
-    [Illustration: The trail from the visitor center takes you across
-    the Niobrara River, up University Hill to the fossil layer, then to
-    the fossil exhibit on Carnegie Hill, and back to the visitor center.
-    The walk takes about one hour.]
-
-    [Illustration: Two fishermen try their luck in the Niobrara.]
-
-
-                            Park Regulations
-
-To ensure your safety and to protect the park’s natural and historical
-resources, several regulations have been established by the National
-Park Service. Collecting of fossils, rocks, plants, or other objects is
-not permitted. Please be sure to leave everything as you find it along
-the trails and throughout the park for others to enjoy. If you have any
-questions about park regulations and policies, please ask the staff. The
-rangers are here to help you and to enforce the regulations.
-
-
-                              Safety Tips
-
-Though snakes are not prevalent, be sure to watch for rattlesnakes as
-you walk about through the park, along the trails, and near the exhibits
-at Carnegie and University Hills. Avoid them if you see them, but do not
-harm them. As a general rule it is best to keep a good distance from any
-wildlife you see, not only to protect yourself and your children, but to
-avoid frightening or hurting the animal. It is best to observe wildlife
-at a safe distance with field glasses. While walking about the park, do
-not take chances by climbing on loose rock, or going into unauthorized
-areas, and do not let your children go beyond your control. Park your
-vehicle in authorized places and observe the normal rules of road safety
-and courtesy while you are in the park, and when entering and leaving
-it.
-
-
-                       Birding Along the Niobrara
-
-
-                        Taking the Annual Count
-
-One of the joys of visiting the national parks, author Freeman Tilden
-once said, is having an unexpected, provocative experience. You go to a
-park to see or do one thing, and you come across something else that
-strikes your fancy as well. Tilden called it serendipity. At Agate
-Fossil Beds National Monument, one such experience might be
-birdwatching. In this piece, Doris B. Gates writes of her annual bird
-surveys in this area.
-
-
-In western Nebraska the northern part of the Great Plains ends at the
-Pine Ridge, an escarpment circling from Wyoming across Nebraska’s north
-edge and winding into South Dakota. A major grass of this mixed prairie
-is little bluestem, Nebraska’s state grass, whose rusty-red hue in fall
-and winter gives much of the state its characteristic color.
-
-These plains are rarely broken by cultivation and only a few houses with
-their few trees break the landscape. The land’s major change comes where
-the Niobrara River, here little more than a narrow creek, cuts a valley
-whose rock outcroppings provide homes for rock wrens, chipmunks, and
-bushy-tailed wood rats better known as pack or trade rats.
-
-    [Illustration: Swainson’s hawk]
-
-Here, since 1967, near Agate Fossil Beds National Monument, my partner
-and I have taken part in the annual Breeding Bird Survey for the U.S.
-Fish and Wildlife Service. Part of one of our survey routes, Highway 29,
-crosses the monument’s west end. We know the area—in June at least—quite
-intimately, when there is nothing quite so beautiful as a sunrise over
-these flower-dotted, green-grassed rolling hills along the Niobrara.
-
-We go many kilometers and make many bird counting stops, then we drop
-into the little valley where the Niobrara flows and suddenly we hear and
-see birds in such rapid succession that we have difficulty getting them
-all named in the three minutes allowed us under the survey rules.
-Actually, three stops are influenced by the river: on the south edge we
-have found a common nighthawk, a lark sparrow, and a Say’s phoebe; on
-the north end the rock wren sings its un-wrenlike song. Near the bridge,
-where a narrow belt of shrubs and trees—mostly willows—hugs the river,
-we have logged the following: common flicker, a red-headed woodpecker,
-eastern and western kingbirds, western wood peewees, a blue jay,
-black-capped chickadees, house wrens, a brown thrasher, robins, yellow
-warblers, black-billed magpies, common grackles, black-headed grosbeaks,
-American goldfinches, and the non-native house sparrow and starling.
-Only once did we see or hear a black-billed cuckoo.
-
-                                                   _continues on page 85_
-
-    [Illustration: Red-winged blackbird chick]
-
-    [Illustration: Long-billed curlew chick]
-
-    [Illustration: Long-billed marsh wren]
-
-    [Illustration: Canada geese]
-
-    [Illustration: Long-billed curlew male]
-
-    [Illustration: House wren]
-
-    [Illustration: Nighthawk]
-
-    [Illustration: Marsh hawk chicks]
-
-    [Illustration: Killdeer]
-
-    [Illustration: Great horned owl]
-
-    [Illustration: Western meadowlark]
-
-    [Illustration: American bittern]
-
-    [Illustration: Pocket gopher]
-
-    [Illustration: Jackrabbit]
-
-    [Illustration: Hognose snake]
-
-    [Illustration: Fence lizard]
-
-    [Illustration: Coyote]
-
-    [Illustration: Pronghorn]
-
-If we stop and peer into a large culvert under the highway we may scare
-out a cloud of cliff swallows whose mud nests are stuck on culvert
-walls. Barn and rough-winged swallows are more rarely seen—usually near
-the Agate buildings.
-
-Near scattered farmhouses we may see logger-head shrikes; by one water
-tank we usually find a few killdeer. These and such birds as the
-long-billed curlew, upland sandpipers, and sharp-tailed grouse break the
-near monotony of such prairie birds as western meadowlarks (Nebraska’s
-state bird), lark buntings, horned larks, and chestnut-collared
-longspurs. Lark buntings line the utility wires, taking off to sing
-their territorial songs, and descending with butterfly-like motions.
-
-Hawks are here—red-tails, Swainson’s, ferruginous, marsh, and the little
-American kestrel—but in small numbers. We search long rows of fence
-posts for a burrowing owl and occasionally see one. Great-horned owls
-frequent tall cottonwood trees around the Agate ranch buildings. This is
-also the country of turkey vultures, golden eagles, and prairie falcons,
-but we have not been lucky enough to see them yet.
-
-Mammals are more elusive. Cattle pasture conspicuously on land formerly
-claimed by the buffalo (bison). We see pronghorns each year. A lone
-coyote is the only other relatively large mammal we have logged. Check a
-good mammal book and you will appreciate what lives here largely
-invisible to the untrained eye: shrews, moles, bats, cottontails and two
-kinds of jackrabbits, pocket gophers, prairie dogs, kangaroo rats,
-voles, several kinds of mice, two kinds of ground squirrel, muskrats,
-beaver, raccoons, minks, badgers, longtailed weasels, two kinds of
-skunks, occasional porcupines and bobcats, white-tailed deer, and mule
-deer. Consider yourself lucky if you see the swift fox, mountain lion,
-and the rare black-footed ferret.
-
-Life abounds here in other forms less noticeable to eyes trained on the
-Breeding Bird Survey: various species of amphibians, reptiles, fish, and
-the numerous insects associated with grasslands. We hear perhaps too
-much about rattlesnakes—western Nebraska has only the prairie rattler,
-whose numbers are now much reduced. Other snakes include western
-hognosed, blue racer, bullsnake, and the plains, wandering, and
-red-sided garter snakes.
-
-
-                  Collections of Agate Springs Fossils
-
-
-                         Museums You Can Visit
-
-Many museums throughout the world have displays of fossils from the
-Agate Fossil Beds. Very few of them actually collected their own
-material. Museum curators are dedicated “horse traders” and
-fossil-swapping is part of the business. When museums such as the
-Carnegie Museum of Pittsburgh or the American Museum of Natural History
-in New York make collections like the ones made at Agate earlier in this
-century, they usually have some trading stock left over after completing
-their study collections and exhibits. They then can trade an extra
-_Menoceras_ slab, for example, for a dinosaur skeleton from some faraway
-corner of the Earth.
-
-At several museums in this country you can see mounted skeletons of
-several animals found at Agate, along with _Menoceras_ slabs (sections
-of rock with the bones still imbedded) or models and dioramas of Agate
-specimens. To the right are listed, in order of proximity to the park,
-some of the museums and their specimens from Agate.
-
-The United States Museum of Natural History, Smithsonian Institution,
-has many fossils that depict the life of the most recent 65 million
-years and several murals by artist Jay H. Matternes showing the life of
-each of the epochs. The Miocene mural, reproduced on pages 20-21 of this
-handbook, is among these reconstructions. It depicts ancient life around
-what is today known as Agate Fossil Beds National Monument.
-
-  The Trailside Museum
-  Fort Robinson, Nebraska 69339.
-      _Menoceras_ slab, skeleton, and restoration
-      _Stenomylus_ skeleton on a slab, and a prepared limb
-      _Palaeocastor_ in a _Daemonelix_
-      _Palaeocastor_ in a plaster cast
-  Museum of Geology, South Dakota School of Mines and Technology
-  Rapid City, South Dakota 57701.
-      _Menoceras_ slab, beautifully prepared
-  The Geological Museum
-  University of Wyoming, Laramie, Wyoming 82070.
-      _Menoceras_, mounted skeleton
-      _Stenomylus_ slab containing most of a skeleton
-  University of Nebraska State Museum
-  101 Morrill Hall, 14th and U Streets, Lincoln, Nebraska 68508.
-      _Moropus_, mounted skeleton
-      _Palaeocastor_ skeleton in a _Daemonelix_; also, two other
-      _Daemonelix_
-      _Menoceras_ slab
-      _Dinohyus_ skeleton
-      _Stenomylus_, a group of skeletons
-  Field Museum of Natural History
-  Roosevelt Road at Lake Shore Drive, Chicago, Illinois 60605.
-      _Menoceras_ slab
-      _Moropus_ skeleton
-  The University of Michigan Exhibit Museum
-  1109 Geddes Rd., Ann Arbor, Michigan 48104.
-      _Menoceras_ slab and mounted skeleton
-      _Dinohyus_ eating dead Menoceras, a diorama
-      _Stenomylus_ skeleton and model
-  Carnegie Museum
-  4400 Forbes Ave., Pittsburgh, Pennsylvania 15213.
-      _Promerycochoerus_ slab
-      _Menoceras_ slab and mounted skeleton
-      _Moropus_, mounted skeleton
-      _Dinohyus_, mounted skeleton
-      _Stenomylus_, three skeletons mounted in a group
-  The American Museum of Natural History
-  Central Park West and 79th St., New York, New York 10024.
-      _Moropus_ skeleton
-      _Menoceras_ slab and skulls, one used in a sequence showing
-      collecting and preparation techniques
-      _Dinohyus_ skull
-      _Stenomylus_, nine skeletons and a reconstruction of the group
-      in life
-  Museum of Comparative Zoology
-  Harvard University, Oxford Street, Cambridge, Massachusetts 02138.
-      _Menoceras_ slab
-      _Dinohyus_ skeleton
-      _Stenomylus_ skeleton
-
-
-                     NPS Areas With Fossil Exhibits
-
-Several fossil sites in the United States are under the protection of
-the National Park Service. Besides Agate, the major ones are:
-
-
-                  Badlands National Park, South Dakota
-
-    [Illustration: Badlands]
-
-Prominent deposits from the Oligocene Epoch, predecessor to the Miocene,
-combine with a rugged, eroded landscape and abundant wildlife to make
-Badlands a park where the natural processes of the past combine with
-those of today. The National Park Service maintains a Fossil Exhibit
-Trail at Badlands and presents fossil cleaning demonstrations. Prominent
-fossils are those of ancient camels, giant pigs, sabertooth cats,
-_Protoceras_, and _Brontotheres_. Mailing address: P.O. Box 6, Interior,
-SD 57750.
-
-
-             Dinosaur National Monument, Colorado and Utah
-
-    [Illustration: Dinosaur]
-
-The late Jurassic muds and sands of the Morrison Formation have been a
-major source of dinosaur bones for more than a century. Steeply tilted
-strata near Vernal, Utah, were the source of tons of bones for the
-Carnegie Museum of Pittsburgh. This quarry site became the nucleus of
-Dinosaur National Monument. The bone-bearing stratum has been exposed by
-careful excavation, so that bones and partial skeletons of numerous
-dinosaurs are exposed in high relief. The entire quarry face is covered
-by a glass-walled structure that forms a large gallery. Mailing address:
-4545 E. Hwy. 40, Dinosaur, CO 81610.
-
-
-           Florissant Fossil Beds National Monument, Colorado
-
-This site has long been famous for its fossils of insects and plants
-preserved in fine-grained sediments. Specimens of _Brontothere_ indicate
-an Eocene age for the deposits. Mailing address: P.O. Box 185,
-Florissant, CO 80816.
-
-    [Illustration: Florissant]
-
-
-                Fossil Butte National Monument, Wyoming
-
-Within the strata of this rock remnant of an ancient lake is one of the
-most extensive concentrations of fossilized freshwater fish known to
-science. The site is about 18 kilometers (11 miles) west of Kemmerer,
-Wyoming. Mailing address: P.O. Box 592, Kemmerer, WY 83101.
-
-
-                Petrified Forest National Park, Arizona
-
-    [Illustration: Petrified Forest]
-
-Here in the Late Triassic Chinle Formation are widespread deposits of
-petrified logs. Some are nearly 2 meters in diameter and 60 meters long
-(6.5 by 197 feet). Preserved in bright colors of opal and other
-minerals, the most common trees are relatives of the living monkey
-puzzle or Hawaiian star pine. Paleontologists believe many of the logs
-floated to the area in Triassic rivers and became stranded. In the
-museum are displays of various fossil plant species and animal fossils
-from the same deposits. Mailing address: P.O. Box 2217, Petrified Forest
-National Park, AZ 86028.
-
-
-             John Day Fossil Beds National Monument, Oregon
-
-With a total of about 5,700 hectares (14,100 acres) in several
-noncontiguous units in north-central Oregon, this park provides an
-extensive record of Earth history dating back at least 37 million years.
-Plant and animal fossils are present in great variety. Mailing address:
-HCR 82, Box 126, Kimberly, OR 97848.
-
-
-             Hagerman Fossil Beds National Monument, Idaho
-
-Within the banks of the Snake River are preserved the last vestiges of
-late Pliocene life before the Ice Age and modern flora and fauna
-appeared. Mailing address: P.O. Box 570, Hagerman, ID 83332.
-
-
-                         Nearby National Parks
-
-While you’re in the Agate Fossil Beds area, why not see some other sites
-in the National Park System? These parks offer a variety of experiences
-from frontier history presentations to caving.
-
-
-Badlands National Park is 97 kilometers (60 miles) southeast of Rapid
-City, South Dakota. This wonderland of bizarre, colorful spires and
-pinnacles, massive buttes, and deep gorges is open all year, though
-blizzards may temporarily block roads in the winter. Campfire programs
-and guided nature walks are presented. Backpackers will enjoy the park’s
-wilderness area. The park has a herd of about 300 bison and some prairie
-dog towns. Mailing address: P.O. Box 6, Interior, SD 57750.
-
-    [Illustration: Devils Tower]
-
-
-Devils Tower National Monument is 47 kilometers (29 miles) northwest of
-Sundance, Wyoming. Known as Mato Tipila (Bear Lodge) to the Lakota, this
-towering landmark looms over the Belle Fourche River in the northeast
-corner of Wyoming. Here the Black Hills meet the plains grasslands, and
-you will likely see prairie dogs, as well as other mammals and a variety
-of birds. The park is open all year. Mailing address: P.O. Box 10,
-Devils Tower, WY 82714.
-
-    [Illustration: Fort Laramie]
-
-
-Fort Laramie National Historic Site is 5 kilometers (3 miles) southwest
-of Fort Laramie, Wyoming. The first fort on the site was built in 1834
-and soon became a lucrative center of the fur trade. The U.S. Army took
-over in 1849, using the fort to protect the Oregon Trail. The fort was
-abandoned by the Army in 1890. Several buildings are furnished as they
-would have been during the Army years of the 1870s and 1880s. The park
-is open all year. Mailing address: HC 72, Box 389, WY 82212.
-
-
-Jewel Cave National Monument is located on U.S. 16, 24 kilometers (15
-miles) west of Custer, South Dakota. The cave’s name comes from the
-myriads of jewel-like calcite crystals that adorn its walls. Tours are
-conducted daily from mid-May through September. Tours, if any, the rest
-of the year are irregular. Mailing address: RR 1, Box 60 AA, Custer, SD
-57730.
-
-    [Illustration: Mount Rushmore]
-
-
-Mount Rushmore National Memorial is 40 kilometers (25 miles) southwest
-of Rapid City, South Dakota. The mountain sculpture of Washington,
-Jefferson, Theodore Roosevelt, and Lincoln is best viewed under morning
-light. From June 1 to Labor Day the faces are illuminated at night. The
-park is open all year. Mailing address: P.O. Box 268, Keystone, SD
-57751.
-
-    [Illustration: Scotts Bluff]
-
-
-Scotts Bluff National Monument is 8 kilometers (5 miles) southwest of
-Scottsbluff, Nebraska. This massive rock promontory rises 245 meters
-(800 feet) above the valley floor, and it served as a landmark to
-Indians, fur traders, and settlers traveling the Oregon Trail. It was
-named for a fur trapper, Hiram Scott, and has remained a symbol of the
-great overland migrations. The park is open all year. Mailing address:
-P.O. Box 27, Gering, NE 69341.
-
-
-Wind Cave National Park is 16 kilometers (10 miles) north of Hot Springs
-in southwest South Dakota. Two worlds meet here: the underground world
-of the cave and the life of the surface prairie. The cave gets its name
-from the wind blowing into or out of the cave. Mailing address: RR 1,
-Box 190, Hot Springs, SD 57747.
-
-
-                      Not So Nearby National Parks
-
-By expanding your travel perimeter even farther beyond Agate Fossil
-Beds, you can take in these other National Park System sites.
-
-
-Bighorn Canyon National Recreation Area straddles the Montana-Wyoming
-border, 67 kilometers (42 miles) from Hardin, Montana, and at Lovell,
-Wyoming. Access to boat ramps and campgrounds is from both ends of the
-long reservoir. Yellowtail Dam tours are given from Memorial Day to
-Labor Day. The visitor centers are open all year. Mailing address: P.O.
-Box 458, Fort Smith, Montana 59035.
-
-
-Little Bighorn Battlefield National Monument is 24 kilometers (15 miles)
-south of Hardin, Montana. Here on June 25, 1876, Lt. Col. George
-Armstrong Custer and five 7th Cavalry companies attacked and were
-surrounded and killed by Indians. Mailing address: P.O. Box 39, Crow
-Agency, MT 59022.
-
-    [Illustration: Rocky Mountain]
-
-
-Rocky Mountain National Park is northwest of Denver and about 3
-kilometers (2 miles) west of the community of Estes Park, Colorado. The
-park is one of America’s most accessible mountainous areas. Trail Ridge,
-which crosses the Continental Divide, offers breathtaking views. Elk,
-mule deer, bear, cougar, and bighorn sheep roam mountain crags, meadows,
-and valleys. Mailing address: Estes Park, CO 80517.
-
-    [Illustration: Theodore Roosevelt]
-
-
-Theodore Roosevelt National Park is on Interstate 94 at Medora, North
-Dakota. A separate unit is 90 kilometers (56 miles) north on U.S. 85. In
-these magnificantly colored badlands along the Little Missouri River
-Roosevelt had an open-range ranch and developed his practical
-conservation philosophy. Both units have campgrounds. Mailing address:
-P.O. Box 7, Medora, ND 58645.
-
-
-                         Armchair Explorations
-
-
-                    Some Books You May Want to Read
-
-  Bartlett, Richard A., _Great Surveys of the American West_, University
-  of Oklahoma Press, 1962.
-
-  Camp, Charles L., _Earth Song: A Prologue to History_, American West
-  Publishing Co., 1970.
-
-  Colbert, Edwin H., _Evolution of the Vertebrates_, John Wiley and
-  Sons, Inc., 1969.
-
-  Cook, Harold J., _Tales of the 04 Ranch_, University of Nebraska
-  Press, 1968.
-
-  Cook, James H., _Fifty Years on the Old Frontier_, University of
-  Oklahoma Press, 1980.
-
-  Gould, Stephen Jay, _Ever Since Darwin: Reflections in Natural
-  History_, W. W. Norton and Co., 1977.
-
-  Howard, Robert West, _The Dawn-seekers_, Harcourt Brace Jovanovich,
-  1975.
-
-  Johnson, Kirk R. and Richard K. Stucky, _Prehistoric Journey: A
-  History of Life on Earth_, Roberts Rinehart, 1995.
-
-  Lanham, Url, _The Bone Hunters_, Columbia University Press, 1973.
-
-  Laporte, Léo F., _Evolution and the Fossil Record_, W. H. Freeman Co.,
-  1978.
-
-  Larson, Robert W., _Red Cloud: Warrior-Statesman of the Lakota Sioux_,
-  University of Oklahoma Press, 1997.
-
-  Mason, Stephen F., _A History of the Sciences_, Collier Books, 1970.
-
-  Meade, Dorothy Cook, _Heart Bags & Handshakes: The Story of the Cook
-  Collection_, National Woodlands Pub. Co., 1994.
-
-  Osborn, Henry F., _Cope: Master Naturalist_, Princeton University
-  Press, 1931.
-
-  Paul, R. Eli, _Autobiography of Red Cloud: War Leader of the Oglalas_,
-  Montana Historical Society Press, 1997.
-
-  Plate, Robert, _The Dinosaur Hunters: Othniel C. Marsh and Edward D.
-  Cope_, McKay Co., 1964.
-
-  Raup, David M. and Steven M. Stanley, _Principles of Paleontology_, W.
-  H. Freeman Co., 1978.
-
-  Romer, Alfred Sherwood, _Vertebrate Paleontology_, University of
-  Chicago Press, 1966.
-
-  Schuchert, Charles and Clara Mae LeVene, _O.C. Marsh: Pioneer in
-  Paleontology_, Yale University Press, 1940.
-
-
-                                 Index
-
-  _Numbers in italics refer to photographs, illustrations, charts, or
-                                 maps._
-
-
-                                   A
-  _Aepinacodon_ _54-55_, 60
-  Agate Fossil Beds National Monument 11, 14, 50;
-      animals at, _20-22_, 24-34, _84_;
-      birding at, 81, _82-83_, 85;
-      established, 17, 78;
-      geology of 23, 47-52;
-      museum specimen of, 38, _86-87_;
-      topography of, 7;
-      visitor information 77-80
-  Agate Springs Ranch 7, 10, 17;
-      excavations at, 38, _39_; fossils from, _40-41_, 86-87
-  Alligator _54-55_, 60
-  American Museum of Natural History 14, 38, 52, 87
-  _Aplodontia_ 32
-
-
-                                      B
-  Badlands National Park, South Dakota _88_, 90
-  Barbour, Erwin H. 11, 14, 38
-  Big Badlands, South Dakota 49, 52
-  Bighorn Canyon National Recreation Area, Montana-Wyoming 92
-  Bittern, American _83_
-  Blackbird, red-winged _82_
-  Bone Cabin, Wyoming 48
-  Breeding Bird Survey, U.S. Fish and Wildlife 81, _82-83_, 85
-  Buteos (buzzard hawks) 28
-
-
-                                      C
-  Cambrian period _46_
-  Camels. _See_ _Oxydactylus_, _Stenomylus_
-  Camping 78
-  Carboniferous period _46_
-  Carnegie Hill _12-13_, 14, 37, 77
-  Carnegie Museum 14, 38, 39, _40-41_, 69, 87, 88
-  Carnivores, small 32-34
-  Cenozoic Era _46_, 47, 49, 52
-  Chalicotheres. _See_ _Moropus_
-  Cheyenne River 52
-  Cleveland, Utah 48
-  Colorado Plateau 49
-  Como Bluff, Wyoming 48
-  Cook, Eleanor Barbour 14
-  Cook, Harold 10, 14, 17, 52
-  Cook, James H. _6_, 8, 10-11, 14, 77;
-      buys Agate Springs Ranch, 7, 10;
-      discovers fossils, 11, 24, 38
-  Cook, Kate Graham 10-11, 14
-  Cook, Margaret Crozier 17
-  Cook Museum of Natural History 17
-  Cope, Edward Drinker _9_, 11, 14
-  Coyote _84_
-  Cretaceous period _46_
-  Curlew, long-billed _82_
-  Cuvier, Georges 42, _43_, 45
-  Custer Battlefield National Monument. _See_ _Little Bighorn
-          Battlefield National Monument_
-
-
-                                      D
-  _Daemonelix_ 33, _69_, 70, 86
-  _Daphoenodon_ _20-21_, 22, 32, 38
-  Darwin, Charles 43, _44_, 45
-  Devil’s Corkscrew _76_
-  Devils Tower National Monument, Wyoming _90_
-  Devonian period _46_
-  _Diceratherium_ 24. _See also_ _Menoceras_
-  _Dinohyus_ _20-21_, 22, 30, 87
-  Dinosaur National Monument, Colorado and Utah 42, 48, _88_
-  Drought 35, 36, 50-51
-
-
-                                      E
-  Ecology 53, 61-73
-  _Entelodon_ 30
-  Entelodont 30
-  Eocene epoch 25, 27, 29, 31, _46_, 49, 53, 63, 88
-  _Equus_ 63
-  Excavations 38, _39_
-
-
-                                      F
-  Field Museum of Natural History 87
-  Flora 7, 10, 53, _54-59_, 60, 71-73
-  Florissant Fossil Beds National Monument, Colorado 53, 88, _89_
-  Folsom, New Mexico 14;
-      spearpoint, 17
-  Fort Laramie National Historic Site, Wyoming _90_
-  Fort Robinson State Park, Nebraska 50, 77
-  Fossil Butte National Monument, Wyoming 89
-  Fossils _38-41_, 47, 86-89
-
-
-                                      G
-  Geological Museum, University of Wyoming 86
-  Geology 35, _46_, 47-52
-  Geese, Canada _82_
-  Gerenuk 29
-  Gering Formation 50
-  Gopher, pocket _84_
-  Graham, Elisha B. 10
-  Graham, Mary 10-11
-  Grasslands 26, 35, 51, 61, 71-72
-  _Gregorymys_ 33
-  Guan 28
-
-
-                                      H
-  Hagerman Fossil Beds National Monument, Idaho 89
-  Harrison Formation 23, 50, 63
-  Hawk _56-57_, 60;
-      marsh _83_;
-      nighthawk _83_;
-      Swainson’s _81_
-  Horses 62-63, _66-67_. _See also_ _Merychippus_, _Miohippus_,
-          _Parahippus_, _Protohippus_
-  Hutton, James 45
-
-
-                                      J
-  Jackrabbit _84_
-  Jefferson, Thomas 42
-  Jewel Cave National Monument, South Dakota 91
-  John Day Fossil Beds National Monument, Oregon 89
-  Jurassic period _46_
-
-
-                                      K
-  Killdeer _83_
-
-
-                                      L
-  Laboratory _40-41_
-  Lamarck, Jean-Baptiste de _43_
-  Laramide Revolution 49
-  Linnaeus, Carolus _43_
-  Little Bighorn Battlefield National Monument 92
-  Lucretius (Titus Lucretius Carus) 42
-  Lyell, Charles 42, 43, _45_
-
-
-                                      M
-  Map _78_, _79_
-  Marsh, Othniel C. _8_, _9_, 11
-  Marsland Formation 50, 51
-  Matthew, W. D. 52
-  McJunkin, George 14
-  Meadowlark, western _83_
-  _Meniscomys_ 32-33
-  _Menoceras_ 14, _20-21_, _22_, _24_, 25, 36, 38, 51, 86, 87
-  _Merychippus_ 52, _58-59_, 60, 62-63
-  _Merychyus_ _20-21_, 22
-  Mesozoic era _46_, 47-49
-  Miocene epoch _46_, 49-52, 71-73;
-      animals of 20-37, 62, 63, _64-69_, 70;
-      birds of 28
-  _Miohippus_ 25-26, 27, 64, _66-67_
-  Mississippi Embayment 35, 49
-  Monroe Creek Formation 50
-  Morrison, Colorado 48
-  _Moropus_ _20-21_, 22, _29-30_, 86-87
-  Mount Rushmore National Memorial, South Dakota _91_
-  Museum of Comparative Zoology, Harvard University 87
-  Museum of Geology, South Dakota School of Mines and Technology 86
-  Museums, fossils at _86-87_. _See also_ _American Museum of
-          Natural History_, _Carnegie Museum_
-
-
-                                      N
-  _Nanotragulus_ 27-28
-  National Park Service 17, 88-92
-  Nighthawk _83_
-  _Nimravus_ 32
-  Niobrara River 7, _16_, 23-24, 36, 37, 50, _54-55_, _60_
-  North Platte River 52
-  _Nothocyon_ 32, 33
-
-
-                                      O
-  Oglala Sioux Indians 7, 11. _See also_ _Red Cloud_
-  _Oligobunis_ 32
-  Oligocene epoch 25, 31, _46_, 49, 50, 52, 53, 70, 88;
-      animals of 61, 63
-  Opossum _54-55_, 60
-  Ordovician period _46_
-  _Oreodon_ 25, _54-55_, 60, 63
-  Osborn, Henry F. 14, 38
-  Owl, great horned _83_
-  _Oxydactylus_ _20-21_, 22, 28, _56-57_, 60
-
-
-                                      P
-  _Palaeocastor_ 14, _20-21_, 22, _33_, 64, _68-69_, 70-71, 77, 86
-  _Palaeolagus_ 34
-  Paleocene epoch _46_, 53
-  Paleozoic era _46_, 47-48
-  _Parahippus_ _20-21_, 22, _27_, _56-57_, 60, 62, 67
-  Permian period _46_
-  Peterson, O. A. 14, 38, 39
-  Petrified Forest National Park, Arizona _89_
-  Pigs 30-31
-  Pine Ridge, South Dakota 52
-  Pleistocene epoch 28-29, _46_, _64_, 67
-  Pliocene epoch 24-25, 27, _46_, 52, 63
-  _Portheus_ 48
-  Precambrian era _46_
-  _Promerycochoerus_ _20-21_, 22, 25, 87
-  Pronghorn (artiodactyls) 63, _84_. _See also_ _Syndyoceras_
-  _Protoceras_ 31
-  _Protohippus_ 62, 63
-  _Pseudaelurus_ 32, _58-59_, 60
-
-
-                                      Q
-  Quaternary period _46_
-
-
-                                      R
-  Red Cloud 9, 11
-  Rhinoceros 24-25, 50, 51, 63
-  Rocky Mountain National Park, Colorado 92
-  Rocky Mountain Revolution 51, 52
-  Runningwater Formation 51
-  Rodents 32-34
-
-
-                                      S
-  Sandpiper, upland _14_
-  Scotts Bluff National Monument, Nebraska 49, _91_
-  Sheep Creek Formation 52
-  Silurian period _46_
-  Smiley Canyon, Nebraska 50
-  Snake, hognose _84_
-  _Stenomylus_ 14, _20-21_, 22, _29_, 37, _39_, 50, _64-65_, 86, 87;
-      _hitchcocki_, 51
-  Sundance Formation 48
-  _Syndyoceras_ _20-21_, 22, _31_
-  _Synthetoceras_ 31-32
-
-
-                                      T
-  Teeth, high-crowned 62-63
-  _Temnocyon_ 32
-  Tertiary period _46_, 53
-  Theodore Roosevelt National Park, North Dakota 92
-  Thompson, Albert 14, 38
-  Toadstool Park, Nebraska 49
-  Tortoise 33-34
-  Trailside Museum, Nebraska 86
-  Triassic period _46_
-
-
-                                      U
-  Uniformitarianism 42, 43, 45
-  University Hill 7, _12-13_, 35;
-      digging at, 14;
-      formation of 37;
-      tourist facilities at, 77
-  University of Nebraska State Museum 86
-
-
-                                      V
-  Visitor information 77-80, 86-92
-  Von Linne, Karl _43_
-
-
-                                      W
-  Wallace, Alfred _45_
-  White River 52;
-      Badlands 31;
-      Beds 49
-  Wildflowers 7, 10
-  Wind Cave National Park, South Dakota 91
-  Wren, house _82_;
-      long-billed marsh _82_
-
-
-  ★GPO: 1999—454-765/00504
-  Reprint 1999
-
-
-
-
-                         National Park Service
-
-
-The National Park Service expresses its appreciation to all those
-persons who made the preparation and production of this handbook
-possible. The Service also gratefully acknowledges the financial support
-given this handbook project by the Oregon Trail Museum Association, a
-nonprofit group that assists interpretive efforts at Agate Fossil Beds
-National Monument.
-
-
-                                 Texts
-
-James R. and Laurie J. Macdonald, authors of “A Landscape Rich With
-Life” in Part 2, are paleontologists who live in Sunnyvale, California,
-and teach nearby.
-
-Doris B. Gates, writer of “Birding Along the Niobrara” in Part 3, is a
-retired biology professor who lives in Chadron, Nebraska.
-
-
-                                  Maps
-
-R.R. Donnelly & Sons Co. 79.
-
-
-                             Illustrations
-
-
-  Jay H. Matternes, who painted the wildlife panoramas and animal
-          features on the cover and in Part 2, is a paleontological
-          reconstruction artist who lives in Fairfax, Virginia. In Part
-          2 his illustrations appear on pages 20-21, 24, 25, 27-33,
-          54-59, 64-69.
-  American Museum of Natural History 9 Cope.
-  Greg Beaumont 14, 81-84.
-  Carnegie Museum 38-41.
-  Library of Congress 43-45.
-  James O. Milmoe 12-13, 15, 16, 76.
-  Peabody Museum of Natural History, Yale University 8.
-  All other illustrations are from the files of Agate Fossil Beds
-          National Monument and the National Park Service.
-
-
-
-
-                    U.S. Department of the Interior
-
-
-The mission of the Department of the Interior is to protect and provide
-access to our Nation’s natural and cultural heritage and honor our trust
-responsibilities to tribes. The National Park Service preserves
-unimpaired the natural and cultural resources and values of the National
-Park System for the enjoyment, education, and inspiration of this and
-future generations. The National Park Service cooperates with partners
-to extend the benefits of natural and cultural resource conservation and
-outdoor recreation throughout this country and the world.
-
-
-
-
-                           Agate Fossil Beds
-
-
-     _Through the remains of animals long extinct, excavated here at
-    this site, Agate Fossil Beds National Monument tells the story of
-    the Miocene Epoch—the Age of Mammals—that occurred 5 to 23 million
-    years ago. The scene on the front cover is from a mural by artist
-    Jay H. Matternes that depicts animals of the Early Miocene._
-
-    [Illustration: _In addition to fossils, the park has an extensive
-    collection of Plains Indian art and artifacts, such as this shirt
-    that belonged to Red Cloud._]
-
-
-
-
-                          Transcriber’s Notes
-
-
-—Retained publication information from the printed edition: this eBook
-  is public-domain in the country of publication.
-
-—Relocated all image captions to be immediately under the corresponding
-  images, removing redundant references like “preceding page”.
-
-—Silently corrected a few palpable typos.
-
-—In the text versions only, text in italics is delimited by
-  _underscores_.
-
-—Conjecturally restored one subsection of the index entry for “Agate
-  Springs Ranch”
-
-
-
-
-
-
-
-End of the Project Gutenberg EBook of Agate Fossil Beds National Monument,
-Nebraska, by United States National Park Service
-
-*** END OF THIS PROJECT GUTENBERG EBOOK AGATE FOSSIL BEDS NATIONAL MONUMENT ***
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-The Project Gutenberg EBook of Agate Fossil Beds National Monument,
-Nebraska, by United States National Park Service
-
-This eBook is for the use of anyone anywhere in the United States and most
-other parts of the world at no cost and with almost no restrictions
-whatsoever.  You may copy it, give it away or re-use it under the terms of
-the Project Gutenberg License included with this eBook or online at
-www.gutenberg.org.  If you are not located in the United States, you'll have
-to check the laws of the country where you are located before using this ebook.
-
-Title: Agate Fossil Beds National Monument, Nebraska
-
-Author: United States National Park Service
-
-Release Date: January 4, 2018 [EBook #56303]
-
-Language: English
-
-Character set encoding: ISO-8859-1
-
-*** START OF THIS PROJECT GUTENBERG EBOOK AGATE FOSSIL BEDS NATIONAL MONUMENT ***
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-Produced by Stephen Hutcheson and the Online Distributed
-Proofreading Team at http://www.pgdp.net
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-                           Agate Fossil Beds
-
-
-                  Agate Fossil Beds National Monument
-                                Nebraska
-
-                            Produced by the
-                        Division of Publications
-                          Harpers Ferry Center
-                         National Park Service
-
-                    U.S. Department of the Interior
-                            Washington, D.C.
-
-
-                   The National Park Handbook Series
-
-National Park Handbooks, compact introductions to the great natural and
-historic places administered by the National Park Service, are designed
-to promote understanding and enjoyment of the parks. Each is intended to
-be informative reading and a useful guide before, during, and after a
-park visit. More than 100 titles are in print. This is Handbook 107. You
-may purchase the handbooks through the mail by writing to Superintendent
-of Documents, U.S. Government Printing Office, Washington DC 20402.
-
-
-                            About This Book
-
-What was life like in North America 20 million years ago? Agate Fossil
-Beds provides a glimpse of that time, long before the arrival of man,
-when now-extinct creatures roamed the land which we know today as
-Nebraska. Part 1 of this handbook introduces you to the park; Part 2
-brings life to the fossil specimens and examines the area's geological
-and ecological evidence; and Part 3 presents concise guide and reference
-information.
-
-
-           Library of Congress Cataloging in Publication Data
-
-
-  United States. National Park Service.
-  Agate Fossil Beds National Monument, Nebraska.
-  (National park handbook; 107) Bibliography: p.
-  Includes index.
-  Supt. of Docs. no. I29.9/5:107
-  1. Vertebrates, Fossil.
-  2. Paleontology--Miocene.
-  3. Paleontology--Nebraska--Agate Fossil Beds National Monument.
-  4. Natural history--Nebraska--Agate Fossil Beds National Monument.
-  5. Agate Fossil Beds National Monument, Neb.
-  I. Title.
-  II. Series: United States. National Park Service. Handbook--National
-          Park Service; 107.
-  QE841.U59    1980    566'.09782'99    80-607119
-
-
-                                Contents
-
-  Part 1 Welcome to Agate Fossil Beds                                   4
-      Worlds of Past and Present                                        7
-  Part 2 A Landscape Rich With Life                                    18
-      _Text: James R. and Laurie J. Macdonald_
-      _Illustrations: Jay H. Matternes_
-      A Visit to the Past                                              23
-      The Mark of Death Upon the Land                                  35
-      The Geologic History of Agate                                    47
-      Ecology: Change and Adaptation                                   53
-  Part 3 Guide and Adviser                                             74
-      Contents for this section                                        77
-
-
-
-
-                   1    Welcome to Agate Fossil Beds
-
-
-    [Illustration: James H. Cook examines a fossil fragment at the
-    quarries near Agate Springs Ranch about 1918.]
-
-    [Illustration: Besides fossils, Cook also collected Indian artifacts
-    and kept many of them on the walls of his study in the ranch house.]
-
-
-                       Worlds of Past and Present
-
-Imagine that you are a healthy young man, raised conservatively in
-Michigan several years after the end of the Civil War. You are a skilled
-all-around hunter and trapper. The railroad has just spanned the
-continent, and stories of the West, its dangers, its people, and its
-opportunities come to you frequently. You and a friend decide you must
-see this land for yourself, and you save your money carefully against
-the day when you will be ready to go west. Around 1869, at age 12, that
-day comes.
-
-At Fort Leavenworth, Kansas, you meet several cattlemen who tell you and
-your friend where to get work as cattle herders. Before many years have
-passed you have been a cowpuncher in Texas, you have fought Comanches,
-and you have bossed a ranch crew for a wealthy Englishman. You go on to
-fight the famous Apache Chieftain Geronimo as a scout with the U.S.
-Cavalry, and you befriend a famous Sioux chief, Red Cloud. You marry,
-buy a ranch in western Nebraska, and raise a family. And you become
-something of a legend in your own time, your ranch known for its
-hospitality to Indian, scientist, traveler--to one and all, rich or
-poor.
-
-A movie script? Not at all--these are the essentials of the life of
-James H. Cook. Known as "Captain," James Cook became the owner, in 1887,
-of the Agate Springs Ranch, founded earlier by his father-in-law. Under
-Cook's watchful eye, the ranch prospered and became a second home both
-for the Oglala Sioux and for paleontologists bent on excavating the
-fossilized remains of the life of 20 million years ago, found here along
-the Niobrara River in western Nebraska.
-
-This land, now encompassing Agate Fossil Beds National Monument, is
-punctuated with low bluffs ascending westward toward the Rockies. It is
-a land of sharp contrasts, of cool, inviting riverbanks and parched
-ridges, the most famous of which are the fossil-bearing Carnegie and
-University Hills. The surrounding grassy plains are a tapestry of wild
-grasses--prairie sandreed, blue grama, little bluestem, and
-needle-and-thread. The wildflowers lupine, spiderwort, western
-wallflower, sunflower, and penstemon add touches of blue, purple,
-orange, yellow, and red to the tapestry. In summer the dark green spears
-of the small soapweed, a yucca, dot the brown grasses of the hillsides.
-And just as they did more than 20 million years ago, cottonwoods and
-willows provide shade and shelter for birds and other animals along the
-river.
-
-    [Illustration: Professor Othniel C. Marsh, back row center, of Yale
-    University and his students look as if they are equipped for a
-    frontier hunting expedition. But instead of looking for live animals
-    in the West, they were hunting for fossilized remains of ancient
-    beasts. Marsh and his crews made many such trips, and it was on one
-    early trip that Cook and Marsh met, in Sioux country.]
-
-    [Illustration: Professor Marsh and the great Sioux chief Red Cloud
-    greet each other in New Haven in 1880.]
-
-    [Illustration: Professor Edward Drinker Cope competed with Marsh for
-    the best fossils. He once made the mistake of reconstructing a
-    skeleton hind end foremost; Marsh never let him forget it.]
-
-Looking out over the rippling grasses, you grasp the fact that Nebraska
-is larger than all of New England and feel the awesome spaciousness of
-the Great Plains. The word "distance" has a different meaning here than
-it does in the East. When James Cook came to the upper Niobrara River,
-the closest town was Cheyenne, Wyoming--more than 160 kilometers (100
-miles) to the southwest.
-
-It was there, in Cheyenne, that Cook met Dr. Elisha B. Graham in 1879,
-the year Graham selected this land for a cattle ranch as an investment
-and as a summer retreat for his family. Graham named the place the 04
-Ranch, apparently because it is near the 104th meridian. Cook visited
-the ranch often in the early 1880s and courted Elisha and Mary Graham's
-daughter Kate. They were married in 1886 and lived near Socorro, New
-Mexico, for a year before returning to Nebraska with their newborn
-child, Harold, and buying the ranch from Dr. Graham, who moved to
-California.
-
-Cook began at once to make improvements to the ranch. He planted trees
-by the hundreds and carried water to them faithfully to get them
-started. As settlers failed to "prove up" their land claims over the
-years, he added new lands to the ranch and changed the name to Agate
-Springs Ranch in recognition of the native moss agates and the many
-springs in the valley. He and Kate raised fine race horses as well as
-cattle.
-
-The period in which the Cooks took over the ranch was one of transition
-from the frontier days of migrations and Indian wars to more settled,
-orderly lives. Ranching and farming became the dominant mode of life in
-the eastern approaches to the Rockies. Even oil exploration played a
-part in the development of the land. The transition was a difficult one
-for many, Indian and settler alike.
-
-In some ways Kate Cook represented both the old and the new in Nebraska.
-She was a fine horsewoman; one day she rode a bucking horse through the
-streets of Cheyenne sidesaddle to win a bet for her husband. She was
-refined, too, having taught herself French so she could read French
-literature. Her mother, Mary Graham, became the first postmistress for
-the small community around Agate.
-
-And James Cook was more than an adventuresome frontiersman. He was
-actively interested in community and national affairs and in current
-scientific questions. He became a patient, knowledgeable mediator
-between the Indians and the settlers, and he was looked upon by the
-Oglala Sioux as a friend and host, and sometimes employer.
-
-The Cooks became involved in a great scientific enterprise quite
-accidentally around 1885, the year before their marriage. On a ride up
-the conical buttes not far from the ranch house, a glitter under a rock
-shelf caught Cook's eye. They found fragments of bones scattered on the
-ground. At first they assumed the bones were those of an Indian. But
-Cook found instead "a beautifully petrified piece of the shaft of some
-creature's leg bone." They carried it back to the house but didn't
-report the find until after they bought the ranch. Erwin Barbour of the
-University of Nebraska was the first to respond to their reports and in
-1892 became the first professional geologist to visit the area and do
-some prospecting.
-
-The Cooks' discovery thrust them and their ranch into a subtle battle in
-the American West, a continuing struggle to find the best fossils with
-which to reconstruct the ancient past. For centuries it had been thought
-that life on our planet was only a few thousand years old, but by the
-late 19th century science had evolved beyond that point of view. Now
-paleontologists and their excavation teams were scouring the West in
-search of fossils that might provide clues to the beginnings of life.
-
-The two most noted antagonists in this feverish search were Professors
-Edward D. Cope of Philadelphia and Othniel C. Marsh of Yale University.
-Cook knew them both, but the discoveries at Agate would wait for the
-next generation of scientists.
-
-    [Illustration: University Hill, left, and Carnegie Hill dominate the
-    Niobrara River Valley. The hills received their names from the
-    paleontological teams that worked them from the University of
-    Nebraska and the Carnegie Museum.]
-
-Cook had first met Marsh in 1874. Marsh had just arrived in Oglala Sioux
-country to hunt fossils, but the Sioux Chief Red Cloud was suspicious.
-Red Cloud was convinced Marsh and his men were just another party of
-gold seekers. Cook, an able linguist, was then trailing cattle from
-Texas to the northern railroads and reservations. He persuaded Red Cloud
-that Marsh wanted only "stone bones" and averted a potentially
-disastrous clash. This incident led to a lifelong friendship between
-Cook and Red Cloud. And for Marsh this proved to be the last of many
-expeditions as he relied on others to send him specimens from likely
-fossil sites throughout the West.
-
-    [Illustration: An upland sandpiper, one of many birds that can be
-    seen at Agate Fossil Beds, perches on a fence post.]
-
-Professor Cope and his crews often worked the same localities as Marsh.
-Like Marsh, Cope tried to get the best specimens, and each occasionally
-outbid the other for them, leaving bewildered farmers and ranchers to
-puzzle over these men's obsession with the past. Conflict also arose
-over the naming of animals previously unknown to science.
-
-The hills of Agate Springs Ranch proved to be a rich archive of ancient
-life. Dr. Barbour and his students confined their efforts to what soon
-became known as University Hill. Thus began a quiet rivalry with Olaf
-Peterson and his crew from the Carnegie Museum in Pittsburgh,
-Pennsylvania, who worked what became known as Carnegie Hill. The most
-numerous fossils these teams found at Agate are the remains of the
-pony-sized rhinoceros _Menoceras_, but the site also is known for
-fossils of the gazelle-like camel _Stenomylus_, the early small horse
-_Miohippus_, and the corkscrew burrows of an ancient beaver,
-_Palaeocastor_.
-
-Other distinguished scientists visited Agate over several decades. Among
-them were Henry Fairfield Osborn and Albert Thompson of the American
-Museum of Natural History in New York. The collections these men made at
-Agate are still being studied and exhibited.
-
-James and Kate Cook's older son Harold caught the fever, too. He became
-a trained geologist and in 1910 married another geologist, Eleanor
-Barbour, daughter of the distinguished Nebraska geologist. The new
-generation of Cooks continued the tradition of hospitality and
-scientific interest, encouraging further excavations of the fossil
-treasures of Agate. Perhaps Harold Cook's greatest moment of scientific
-glory came in 1926, when he and other scientists participated in the
-finds at Folsom, New Mexico, which proved to be a turning point in the
-study of the human prehistory of North America. George McJunkin, a black
-cowboy, had spotted the ribs of an animal protruding from the banks of
-an arroyo. The Folsom spearpoint and the bones of an extinct form of
-bison found there indicated that humans had lived on this continent for
-more than 10,000 years, a startling revelation at that time though today
-scientists put the figure at more than 40,000 years.
-
-    [Illustration: Next to the fence stands a windmill, which once
-    provided water for excavation teams.]
-
-    [Illustration: The narrow Niobrara River winds through the
-    surrounding tableland, carving out bluffs and exposing occasional
-    fossils.]
-
-In time the Cooks' house became a repository for a substantial number of
-Indian artifacts and natural history specimens. On summer weekends and
-holidays tourists ventured out to the ranch to see the Cook Museum of
-Natural History. James Cook personally guided many through the
-collection, but usually the whole family participated, leading the
-curious through three rooms and a small hallway.
-
-Harold Cook wanted Agate Springs Ranch to provide an enduring memorial
-to the ancient past. Soon after his death in 1962 his second wife,
-Margaret Crozier Cook, and friends began a campaign to add the fossil
-beds to the National Park System. Their efforts succeeded in 1965, when
-Congress authorized the establishment of Agate Fossil Beds National
-Monument.
-
-Today you can walk about Carnegie and University Hills where the great
-digs took place. You can see a few exposed fossil specimens, and you can
-try to recreate in your mind the life and landscape of this part of
-Nebraska 20 million years ago. To help you do that, we have asked
-paleontologists James R. and Laurie J. Macdonald, in Part 2 of this
-handbook, to take you on a journey to the past and then examine the
-evidence.
-
-
-Welcome to the worlds of past and present at Agate Fossil Beds National
-Monument.
-
-
-
-
-                    2    A Landscape Rich With Life
-
-
-                _Text: James R. and Laurie J. Macdonald_
-                   _Illustrations: Jay H. Matternes_
-
-    [Illustration: This mural depicts life in the Agate Fossil Beds area
-    in the early Miocene Epoch, about 20 million years ago when the
-    story on the following pages takes place. The painting is a
-    composite of life at that time; if you had been there then, you
-    would not have been able to see all of these forms of life together
-    at any given moment! The original mural hangs in the fossil halls at
-    the Smithsonian Institution's National Museum of Natural History in
-    Washington, D.C.]
-
-    [Illustration: Key to mural]
-
-
-  1/Moropus
-  2/Promerycochoerus
-  3/Menoceras
-  4/Oxydactylus
-  5/Daphoenodon
-  6/Stenomylus
-  7/Dinohyus
-  8/Merychyus
-  9/Palaeocastor
-  10/Parahippus
-  11/Syndyoceras
-
-
-                          A Visit to the Past
-
-Come enter into our imaginations and return to a day along the Niobrara
-River in western Nebraska 20 million years ago. Let's go back and have
-an imaginary look. To set the mood, think about the wild animal movies
-made in modern Africa during the last 40 years. Think of a land swarming
-with life, of extensive grasslands dotted with trees through which great
-herds of grass- and leaf-eating animals are wandering. Look sharply into
-the shadows under the trees and amid the high grass where the
-meat-eaters are resting or stalking their prey. When you have this
-picture of wildlife in mind we're ready for our journey into the past.
-
-Projecting ourselves back those 20 millions of years, we find ourselves
-in a landscape filled with animals. Some of the animals are not much
-different from those living today, but others are so bizarre that you
-may have a hard time believing they really existed.
-
-Dawn is building a new day, and those animals which hunt and feed at
-night are disappearing into their lairs. There are so many kinds of
-livings to be made that the day isn't long enough for all animal
-varieties to be about and active only in daylight. As the light spreads
-over the land we see that it is an open, sunny place of mixed grasses
-and trees--mostly grassland, but here and there single trees or small
-clumps not big enough to be called groves. We would call it a savanna.
-
-A broad river runs through the land, and for lack of a better name we
-can call it the Niobrara or "Running Water," the name given by Indians
-to the much smaller modern stream. This ancient Niobrara was a bold,
-wide stream with deep pools and sandbars. It was not cutting a valley as
-its modern counterpart is doing, but was carrying sand and silt down
-from the then-young Rocky Mountains. It sometimes flooded, and as it
-spread out over the wide, flat plain it deposited layers of sand and
-silt that geologists today call the Harrison Formation. The ancient
-Niobrara and other similar rivers spread the same sediments over nearby
-areas in eastern Wyoming and southwestern South Dakota. In the
-sediments, paleontologists would one day find millions of bones.
-
-Our ancient river was the center of life for untold numbers of animals.
-They lived in it, along its banks, in the willow thickets that grew on
-its more permanent sandbars, and on the broad, tree-dotted plains that
-stretched to the horizon beyond the river's normal course. Great herds
-of small horses, rhinoceroses, camels, and other dwellers on the savanna
-came to water holes to drink and perhaps to wallow in the cool and
-refreshing pools. Although all else might be anticlimactic, let's look
-at the rhinoceroses first.
-
-We know that in the modern world rhinos belong in Africa and
-southeastern Asia, not North America, yet this continent was the major
-home of these strange beasts for millions of years. Rhinos did not
-become extinct in North America until about 5 million years ago, during
-the Pliocene (see geologic time chart on page 46). Along the ancient
-Niobrara the rhino herds are not made up of the giant mammals we see in
-zoos today. The ones we see moving slowly toward the river on this early
-Miocene day are no larger than big domestic pigs. They are the first
-among the rhinos to have horns--not one behind the other, but a pair
-near the end of the nose, side by side. To scientists today these rhinos
-are known as _Menoceras_. The name _Diceratherium_, once used both for
-these small rhinos and a larger type of ancient rhino, now refers
-accurately to just the large rhino.
-
-    [Illustration: _Menoceras_]
-
-Look off to the south. There's a herd moving slowly but purposefully
-down to its favorite watering hole. You can see that the males have the
-paired nose horns, and that the females, which are about the same size,
-do not. Trotting amid the herd are fat little colts whose seriousness of
-purpose belies their youth. The herd seems to be made up of about 50
-individuals moving through the tall grass like a flattened dark gray
-cloud. Suddenly they are startled by a large cat or dog stalking through
-the grass, and all the males on the side nearest the enemy bunch
-together to face the hungry hunter. Most of the herd continues to flow
-across the plain, and when the danger is past the guardian males catch
-up in a lumbering gallop.
-
-Finally the herd reaches the river and spreads out through the shallows.
-It is hot today, and the flies are biting even through the tough rhino
-hides. Many of the adults go into deeper pools to roll and soak while
-the young drop their serious attitudes and frolic in the shallows.
-
-As the day wears on, the herd leaves the river and feeds on the leaves
-and stems of scattered trees and willow thickets along the river. When
-twilight comes, the herd draws together, colts and females toward the
-center and bulls around the edges. After a period of milling and
-pushing, the herd finally beds down for the night, with only the
-perimeter guards moving around on the edges.
-
-The daily routines of the other herds of grass- and leaf-eating animals
-generally follow somewhat different patterns from that of the rhinos. Of
-them, only the piglike oreodons wallow in the river. The others spend
-nearly all their time out on the savanna, coming to the river only at
-dawn or dusk to drink.
-
-Oreodons were among the most abundant medium-sized animals of the Middle
-Tertiary. A strictly North American group, they have been described as
-looking like a cross between a sheep and a pig. As small as a house cat
-or as big as a domestic pig, these mammals reached a peak in abundance
-and variety between the Middle and Late Oligocene (though they are known
-from the Late Eocene through the Late Miocene). This peak probably has
-never been equalled by any other group of mammals in such a size range.
-
-As we look out among the herds of animals dotting the plain, we can see
-only a few small bands of oreodons. There's a group coming toward us
-now. These are some big, ugly ones with large triangular-shaped heads.
-The backs of their cheek bones flare out far to the sides, so that with
-their narrow snouts they are most peculiar looking. Their bodies are
-long and rather nondescript, and their legs are short but slender. This
-particular kind is known as _Promerycochoerus_ ("before ruminant hog")
-and is just about the largest of the oreodons. They are really a rare
-sight here at Agate. Perhaps the large herds of _Menoceras_ fill their
-ecologic niche locally, and the oreodons have found they cannot
-successfully compete with the rhinos for food, water, and living space.
-After all, not everything can fit into Paradise.
-
-    [Illustration: _Promerycochoerus_]
-
-Look to the northeast: there's a herd of _Miohippus_ ("Miocene horse")
-wading into the river to drink and browse in the willows along its
-banks. Let's walk toward the herd slowly and quietly. We should take an
-especially good look at this herd--they are part of a doomed race! The
-genus _Miohippus_ is making its last stand at this time. When conditions
-change, well adapted species may restrict their ranges to what is left
-of the old environment; they may adapt, if they are able, to the new
-conditions; or they may not survive if they cannot adapt.
-
-_Miohippus_ did all these things. Some species of the genus became
-extinct. Some evolved into something else. But the end result was the
-complete termination of the genus _Miohippus_ as paleontologists
-recognize it. Much of the environmental pressure coming to bear on the
-genus _Miohippus_ was a result of mountain building to the west. As the
-young Rockies rose, rain-bearing winds from the oceans far to the west
-were wrung of their moisture. This same circumstance makes the high
-plains a land of little rain today.
-
-The scattered trees and groves we see from our vantage point of long ago
-will disappear and be replaced with a sea of drought-tolerant grasses.
-In effect, the savannas will give way to prairies. _Miohippus_ will soon
-be yielding its place to descendants which can eat grass as a steady
-diet. Grass is much harsher on the teeth than the foliage that
-_Miohippus_ eats. In eating grass, grazing animals pick up sand and silt
-enough to quickly wear away teeth designed for leaf-eating. The
-descendants of _Miohippus_ will become better runners, too, with longer
-and more powerful legs. As the trees disappear there will no longer be
-friendly clumps of greenery to hide behind when hungry meat-eaters are
-on the prowl. From now on, fleetness of foot will be a most important
-factor in horse survival.
-
-_Miohippus_ will also give rise to somewhat larger forest horses that
-will survive on into the Pliocene in patches of woodland. They will be
-little changed except in size (some came to be nearly as large as the
-modern horse), and some of them will even cross the Bering Land Bridge
-into Eurasia. This is the last time, however, that we'll see these
-primitive horses in large numbers here in North America.
-
-There's another herd of small horses moving across the plain toward the
-river from the south. These are feeding as they move across the savanna,
-eating both leaves from the scattered trees and grass from the prairie.
-They seem to be enjoying their mixed diet and thriving on it, so they
-won't be too badly hurt in the geologically near future when they have
-to eat mostly grass. This is _Parahippus_ ("near horse"), a new kind of
-horse just recently evolved from _Miohippus_.
-
-    [Illustration: _Parahippus_]
-
-_Parahippus_ is a horse of destiny. For a long time some individuals of
-_Miohippus_ carried a little extra wrinkle of enamel on the crowns of
-their upper grinding teeth--and now the wrinkle occurs in all
-individuals of _Parahippus_. Because of it, _Parahippus_ can eat grass
-without wearing out its teeth before reaching breeding age, making it
-possible for most individuals to reproduce before dying. The little
-wrinkle is passed on. It's only a small advantage, but such is the stuff
-that survival and evolution are made of. _Parahippus_ is the forerunner
-of a vast array of different three-toed, long-limbed prairie horses that
-will be the most numerous members of their family until nearly the end
-of the Pliocene. From one of their descendants will come the first
-one-toed horse--the direct ancestor of our modern horses.
-
-More herds are moving in on the river as the morning grows. There's a
-group of something very small moving through the tall grass, but it's
-completely hidden. Only the swaying of the 60-centimeter-tall blades
-shows that a number of animals are hurrying toward the river. Now
-they've moved out into an area of cropped grass, and we can see a herd
-of the diminutive deerlike _Nanotragulus_ ("dwarf goat"). Not a great
-deal larger than a house cat, these little "deer" have tall grinding
-teeth well adapted for grass-eating. Their ancestry goes back for
-millions of years into the Late Eocene, when some of their ancestors
-stood less than 15 centimeters (6 inches) high at the shoulder. But
-their entire family is soon to become extinct. They are part of the
-grazing community, although they eat leaves and softer vegetation just
-as readily. We call them "deer" because they look just like miniature
-deer, but the two families are really only distantly related.
-
-As this group scampers toward the river, we can see that they have a
-peculiar crouching gait--their forelegs are so much shorter than their
-hind legs that they seem to be running continuously downhill. They are
-dainty little animals with small, delicate heads and short, slender
-limbs. They can bound swiftly away if danger threatens, but they'd
-rather hide in the thick brush. A few of the females have fawns with
-them, tiny things less than 10 centimeters (4 inches) tall. Look at them
-all scatter! The shadow of a hawk has passed over the group, and in
-their fright they've dived for some nearby willows. Young _Nanotragulus_
-either learn to duck down at the sight of a passing shadow or they don't
-get a chance to learn at all. This time they all got away, and the hawk
-will have to look elsewhere for a meal.
-
-Buteos or buzzard hawks are common along the Niobrara in the Early
-Miocene, sailing on the warm updrafts on broad, short wings that let
-them ride the lightest airs. They swoop down on the mice and pocket
-gophers, young rabbits and beavers, baby "deer" and sometimes careless
-birds that live on this savanna. All manner of meat-eaters depend on the
-small animals for food, and the little _Nanotragulus_ are most
-vulnerable as they move through the canopy of grass.
-
-There don't seem to be any other herds moving into view just now; but
-while we're on the subject of birds, over there in that patch of short
-grass is a bird rarely seen in North America anymore. It's a guan, a
-ground-living bird related to the grouse and sagehens. It must be far
-from home this morning; most of its time is spent in the thick brush
-farther back from the river. A heavy body and long neck and tail make
-this animal easy to identify.
-
-    [Illustration: _Oxydactylus_]
-
-Let's look at some of the individuals and small groups that are moving
-or resting within view. The camels with the very slender legs and long
-necks are called _Oxydactylus_ ("sharp finger"). They are browsing on
-the willows where the herd of Nanotragulus ran to hide. _Oxydactylus_ is
-an important camel, standing about at the midpoint in the evolution of
-this North American family of mammals. The camels will remain
-stay-at-homes in the continent of their origin until they spread into
-Eurasia and South America at the beginning of the Pleistocene Epoch,
-some 17.5 million years after the rhinos died out at Agate. There are
-many species of _Oxydactylus_; the one we are looking at stands about
-1.2 meters (4 feet) high at the shoulder. Notice that they don't have
-humps on their backs; in this lush land there is no need to store fat
-against a time of possible starvation.
-
-    [Illustration: _Stenomylus_]
-
-Speaking of camels, here comes a herd of _Stenomylus_ ("narrow tooth")
-bounding through the tall grass on the south bank of the river. This is
-a strange little long-neck camel that strayed off the main line of the
-family's evolution. Less than 60 centimeters (24 inches) high at the
-shoulder, it looks very much like the living African antelope called the
-gerenuk. _Stenomylus_, with its long and delicate legs and tall
-cheek-teeth, is perfectly adapted for living in and eating the abundant
-grass which billows on this tree-dotted plain. Yet many of the little
-_Stenomylus_ are going to share a tragic time with hundreds of
-_Menoceras_ only a year or so from this day we are visiting. Later,
-we'll move ahead to that time so you can see that natural disaster, now
-preserved in rock, as it happened.
-
-When you travel back 20 million years in time you would expect to find
-unbelievably bizarre animals. So far, we've seen some offbeat specimens,
-but there has been nothing really out of this world. Now, if you look to
-the north by the lone oak tree, you will see a real prize. Do you see
-that hulk stepping out of the shade? No, it isn't the Dragon of the
-Ishtar Gate, though it might pass for a mythical beast. What a wonderful
-animal! A head like a large horse's, a neck somewhat slimmer, long front
-legs, sloping back, short hind legs, and a little switch tail. Watch
-with your field glasses when it moves out onto the bare ground. See the
-feet? They don't have hooves; each toe ends in a great curved claw! This
-is one of the fabulous chalicotheres, a relative of the horses and the
-rhinos. There were never very many of them living at one time, but the
-family lived in Eurasia from the Eocene, some 55 million years ago,
-through the Pleistocene; and here in North America from the Late Eocene
-to the Middle Miocene.
-
-    [Illustration: _Moropus_]
-
-This chalicothere is named _Moropus_ ("sloth foot"), and it is little
-wonder that when paleontologists first discovered his foot bones
-(without an associated skull) they thought they had found the feet of a
-ground sloth. Let's watch _Moropus_ as it ambles slowly across the
-plain, its strange stilted walk a little like that of the modern
-giraffe. Other animals move aside as _Moropus_ strides through the
-grass. He's a browser, an occasional grass-eater, and even a digger of
-easily accessible roots and tubers. Like his cousins the rhinos, he
-isn't at all bright, and he has a very short temper. When he's annoyed,
-he kicks out with those claws and every animal with good sense leaves
-him alone. He's respected by meat-eaters and plant-eaters alike. He
-walks by himself and everything else detours around him.
-
-    [Illustration: _Dinohyus_]
-
-Look down toward the river, and we may see an exception. That two-meter
-(six-foot) high "pig" walking away from the river, covered with mud, is
-heading right toward the _Moropus_. His name is _Dinohyus_ ("terrible
-pig"), and he's just as short-tempered and stupid as _Moropus_. He looks
-like a giant peccary, but his size and over-large head give him away as
-an entelodont ("complete tooth"). These are pig-like animals, usually of
-large size, that aren't related to the domestic pigs at all. _Dinohyus'_
-skull is nearly one meter (three feet) long, and those tusks are as
-thick as a man's wrist. Though we missed seeing him earlier, he must
-have been wallowing in the mud under the overhanging willows. Now he's
-heading away from the river in search of lunch. He's not very choosy
-about what he eats; it might be succulent leaves or fruits, or even the
-carcass of a dead animal. _Dinohyus_ is an omnivore, eating almost
-anything that has nourishment.
-
-Right now it looks as though he's on a collision course with the
-_Moropus_. He's seen the larger animal, has stopped in his tracks, and
-is pawing the ground with his front feet. Up goes his head--and listen
-to that roar! He's getting a good temper worked up. Off he goes at a
-full gallop, right toward the _Moropus_. It's hard to believe that an
-animal as big as that pig could charge so fast. And look at the
-_Moropus_! He's finally realized in his dim way that he's about to be
-attacked. Up he goes on his hind legs, holding his front legs out ready
-for a downward blow with all eight claws. But suddenly _Dinohyus_ shifts
-his course just slightly, lets out another loud bellow as he avoids the
-_Moropus_, and thunders off toward the open prairie.
-
-_Dinohyus_ has a smaller relative around here somewhere, a little fellow
-just over one meter (three feet) high, called _Entelodon_. His head is
-long and low and has flaring cheekbones and bumps along the underside of
-the jaw like his larger cousin's. Another pig that lives along the
-Niobrara is _Desmathyus_ ("bond [filling a gap] pig"), a true North
-American pig or peccary. Its appearance probably wouldn't surprise
-anyone; it looks very much like the peccaries that live in the American
-Southwest today. Its distant cousin, the domestic pig, was domesticated
-in the Old World from a European species of wild hog, and it was spread
-throughout the world by European colonists. In America, peccary
-evolution has run a long and conservative path. This group has changed
-relatively little in the 35 million years since it first appeared in the
-Late Eocene.
-
-    [Illustration: _Syndyoceras_]
-
-Now for another weird and wonderful beast! Trotting daintily out of a
-thicket on our left is a herd of something you might think were deer or
-pronghorn. But if you look closely you'll see that they have two pairs
-of curving, unbranched horns on their heads, not the single pair of
-prongs you'd expect on a pronghorn. These are _Syndyoceras_ ("together
-horn"), members of a family of mammals found only in North America and
-now extinct. Even on the Early Miocene day we're visiting, they are
-scarce, moving only in small herds. The rear pair of horns is not
-remarkable, but the front ones, which rise from a large bump near the
-nose, curl up and away from each other, ending in blunt tips.
-
-The first member of this family was _Protoceras_, which lived in the
-hills and mountains of western South Dakota during the Late Oligocene,
-just a few million years before the day we are visiting at Agate.
-Paleontologists have found battered scraps of its skeletons in the White
-River Badlands where perhaps they were washed by heavy spring rains
-running off the hills to the west. _Protoceras_ had six bony bumps on
-its head that presumably bore short horns; one pair was over the nose,
-another was over the eyes, and a third was near the back of the skull.
-Probably it was the direct ancestor of _Syndyoceras_.
-
-If _Syndyoceras_ fails somehow to qualify as grotesque, let's jump a few
-million years into the "future" and look at his Late Miocene descendant,
-_Synthetoceras_ ("combined horn"). Here was an animal on a par with
-unicorns and cyclopses. Like _Syndyoceras_ he had two tall horns at the
-back of his head; but something had happened to the curved ones on his
-nose. They had, during several million years of evolution, grown
-together into a single shaft and then spread out again to the sides and
-up. What a pity there were no little boys then, for here we have the
-world's first and only self-propelled slingshot! Tie a rubber band to
-the tips of his nose horns, fill your pocket with pebbles, and saddle
-up.
-
-You may be wondering by now about the smaller animals--the rodents and
-small carnivores. We have not seen any of them so far. Most carnivores
-work at night, but there should be a few about. Down by the river is a
-pair of _Oligobunis_ ("little cusp") hunting near the water's edge. They
-look something like modern badgers but are really more closely related
-to the weasels. If you look just to the right of the herd of
-_Stenomylus_ we were following earlier you might be able to catch a
-glimpse of a stalking cat about the size of a mountain lion. It's
-probably either an advanced _Nimravus_ ("ancestral hunter") or an early
-_Pseudaelurus_ ("false cat"), but we'll have to get a closer look before
-we can be sure. Whichever it is, it's on the main line of cat evolution
-and will eventually end up in our familiar _Felis_ and the other living
-cats. There should also be some sabretooth cats lurking about; they are
-found in nearby deposits of the same age, though not at Agate itself.
-
-    [Illustration: _Daphoenodon_]
-
-If you look very closely at the thicket just south of us on the hillside
-you can see several fox-like dogs hunting rodents. This _Nothocyon_
-("false dog") seems to have filled approximately the fox niche during
-the Early Miocene. Some coyote and wolf-sized dogs are in the area too.
-_Daphoenodon_ ("blood-reeking tooth") is about coyote size. _Temnocyon_
-("cutting [tooth] dog"), is a little larger, probably substituted for
-the wolf in the local fauna, and is characterized by its heavy head and
-long, strong jaws. If we could get a close look at its teeth, we would
-see that they are like those of the Cape Hunting Dog living today in
-South Africa.
-
-Let's move away from the river a half-kilometer (0.3 mile) or so and see
-if we can find something different. That thicket ahead might produce a
-couple of rabbits. Look, there at the edge of the thicket: a _Nothocyon_
-has caught something. It's a _Meniscomys_ ("crescent mouse"), an early
-relative of the living mountain beaver _Aplodontia_. Today, a single
-species of _Aplodontia_, the last of the line, is found only in the
-mountains of the West Coast. It's the most primitive living rodent, not
-related to the Canadian beaver, and sole survivor of a suborder which
-was the earliest rodent group to evolve. _Meniscomys_ was one of the
-most prominent members of the group during the Miocene. It had a round
-furry body, a round head with protruding incisors a bit like a true
-beaver's, and no visible tail.
-
-Watch your step. There is the mound of a pocket gopher. It is neither
-our familiar western gopher _Thomomys_ ("heap mouse") or the "eastern"
-pocket gopher of the Great Plains, _Geomys_ ("earth mouse"), but an
-ancient relative, _Gregorymys_ ("Gregory's mouse"). It must be pretty
-successful as a burrowing animal, because we find it all over the
-western United States in the Early Miocene.
-
-    [Illustration: _Palaeocastor_]
-
-A hundred meters (300 feet) more and we'll show you the surprise of the
-day. Here we are in what looks like a prairie dog town. But those aren't
-prairie dogs. They're a little larger, and quite unfamiliar by modern
-standards. Can't guess what they are? These are beavers--_Palaeocastor_
-("ancient beaver") to be exact. Here in the Early Miocene of North
-America, beavers don't build dams. In fact they live neither at the
-water's edge nor, like muskrats, in the water. They dig deep, spiral
-burrows in well drained ground. Some of their burrows are 2.5 meters (8
-feet) deep, but 2 meters (6.5 feet) is about average. Down and around
-and around the burrows go, like giant corkscrews, always ending in
-straight shafts slanting slightly upward so that living chambers will
-not be flooded by rainwater running down the burrows.
-
-Paleontologists have called the preserved burrows "devil's
-corkscrews"--_Daemonelix_--since the time they were first found. At
-first, scientists thought they might be holes left by the giant tap
-roots of some unknown plant. But when _Palaeocastor_ skeletons were
-found in the bottoms of the spirals, almost everyone had to concede that
-they were truly beaver burrows. Admittedly, the skeleton of a
-_Nothocyon_ was found in one burrow; but this predator probably followed
-a beaver home for supper and just stayed. Three other kinds of beavers
-lived around Agate in the Early Miocene, but their bones have never been
-found in the burrows. No one knows what they did for homes: perhaps
-their burrows were much shallower or were in the river banks where
-running water soon destroyed them.
-
-Near the river bank in some soft sand is a nest of tortoise eggs. The
-hot sun has brought the babies out of their shells and they're stumbling
-off in all directions. Right now the biggest is only about twice the
-size of a silver dollar; but when they're grown they'll be about 60
-centimeters (24 inches) across the shell, or perhaps even larger.
-They're strict vegetarians, grazing and browsing on soft plants and
-leaves. There are probably some pond turtles around too, but we've never
-seen any.
-
-A little farther up the bank, under the roots of that big walnut tree,
-is a rabbit's burrow. Several _Palaeolagus_ ("ancient rabbit") live
-there with their many offspring. Although they look very much like
-cottontails, their ears are smaller and they haven't the same leaping
-and running ability. They'd much rather hide than flee their enemies.
-
-
-These dwellers of the savanna, common during the Miocene Epoch, comprise
-the major species found at the Agate Fossil Beds. Their discovery in the
-late 1800's and early 1900's was highly important to the young science
-of paleontology. In those decades of major discoveries, large gaps
-remained in the story of evolution. Quarries like those at Agate helped
-provide the missing pieces of the puzzle. In their time, the discoveries
-at Agate were an important contribution toward understanding the world
-far beyond the dawn of mankind.
-
-Today, advances in paleontology still depend primarily upon major field
-discoveries, but paleontologists also make use of highly refined
-analytical and measurement techniques. Closely connected with
-paleontology are several other sciences, among them geology, zoology,
-and botany. The paleontologist, for example, must depend on geology to
-provide important answers about the age of fossil specimens. Fossil
-botanical specimens, in turn, can provide answers about animal diets and
-climate. Though paleontology may center on the study of fossil remains,
-it is an interdisciplinary science. This fact will become increasingly
-apparent in the following chapters, which reveal the strands of evidence
-used in constructing the picture of Miocene Agate.
-
-
-                    The Mark of Death Upon the Land
-
-Even in Paradise an occasional calamity can occur. Agate's misfortune
-appeared in the form of a drought. To the west of the plain built by the
-ancient Niobrara River, the Rocky Mountains began to rise again. This
-renewed uplift, after millions of years of relative quiet, eventually
-led to an even drier climate and a replacement of the savanna with a
-landscape of unbroken grasslands from the mountains to the Mississippi
-River and beyond. Trees then could survive only on canyon slopes along
-the courses of the few large remaining rivers that crossed the plains.
-Those rivers flowed toward the central lowlands of North America, once
-an embayment of the Gulf of Mexico. This Mississippi Embayment, as it is
-called by geologists, extended as far north as the present location of
-Cairo, Illinois.
-
-During the first rumbles of this upheaval there were occasional
-instabilities in the weather of the Great Plains. From the fossil
-evidence of Carnegie Hill, University Hill, and the _Stenomylus_ quarry,
-we can see that drought touched the land.
-
-What happens when disaster stalks the land? That question, so pertinent
-to an understanding of fossil deposition at Agate, can be answered best
-by looking at the normal scheme of life. Animal populations are cyclic,
-increasing rapidly to near the highest numbers which can be supported on
-available food supplies. If times are good, animal populations can be
-quite high. If the food supply decreases, massive dieoffs result.
-Successive cycles of plenty and poverty then produce high populations
-followed by dieoffs.
-
-The fossil evidence suggests that a prolonged drought occurred during
-the Golden Age at Agate, resulting in death everywhere. The vast numbers
-of rhino skeletons preserved at Carnegie Hill and University Hill
-provide paleontological evidence that the drought must have lasted for
-several years.
-
-Climates change slowly, and there are wet and dry cycles. Every rancher
-and farmer discovers this when he plows new land during a wet cycle, for
-sooner or later drier years catch up with him. He expects the optimum to
-be the standard; but he is badly hurt during average times, and really
-suffers when the dry years come. It is the same with populations of wild
-animals. When the times are good and the grass and trees are lush, fat,
-and green, more of the young survive and the whole population
-flourishes. The plant-eaters expand their herds and the meat-eaters
-increase to keep up with the better food supply the plant-eaters
-provide. In each case the standards for survival are lowered, and the
-less than perfect can survive and in turn produce young of their own.
-But when the water fails and plants refuse to grow, the herbivores
-starve and the carnivore population in turn declines. Nature is
-indifferent--neither cruel nor kind. When times are bad every species is
-improved, for the strongest and most tenacious survive to reproduce
-themselves. There are benefits to hardship.
-
-So it was at Agate only a year or so after the day of our visit. The
-river died for a while. As with many rivers much of its water flowed
-beneath the surface, through the sand and gravel of the bed. When the
-ancient Niobrara died there was still water moving through the sands and
-filling the low spots in its bed. Some animals could dig down to it and
-survive, others could stake claims to the diminishing water holes. So
-the thirsty, suffering herds of _Menoceras_ went to the river and found
-no water. The strong held the water holes. The smart dug into the sand
-and made their own water holes. The rest died. They died by the
-hundreds, and thousands. Mixed with the carcasses of _Menoceras_ were
-other victims: occasional chalicotheres, giant pigs, oreodons, cats,
-dogs, and a variety of equally thirsty smaller animals. Perhaps most of
-the animals went farther up or down stream, or perhaps they chose not to
-die at the river. Whatever the pattern of dying might have been, we know
-that _Menoceras_ left untold numbers of skeletons on the broad, flat,
-and dry bottom of the ancient Niobrara.
-
-Finally the rains fell in the mountains to the west. The river filled
-with water again and ran in sheets across the plain. At Agate the
-millions of _Menoceras_ bones and lesser numbers of the bones of other
-animals were swept for a few hundred meters downstream and into some
-sort of backwater or river lake--possibly a great meander, or an oxbow
-lake. There, like a gigantic mass of jackstraws, they were piled in a
-tangled mat 30 centimeters (12 inches) thick, covering an unknown number
-of hectares. All we really know is that they were moved far enough to
-get thoroughly jumbled, but not far enough to be badly broken or much
-eroded by the action of the water.
-
-The mass of bones was soon buried by the sands and silts dropped by the
-reborn river, and by wind-carried debris swept off the parched land.
-Once buried, the bones were partially petrified by mineral water flowing
-beneath the surface. The land was built up a few hundred meters by
-sediments continually brought down from the mountains to the west.
-Eventually, continued uplifts of the Rockies and the Great Plains
-combined with erosional cycles to leave the modern Niobrara River. The
-two erosional remnants known today as Carnegie and University Hills were
-produced by the cutting of the modern river system. On the sides of
-these hills were exposed the tangle of bones which marked the site of
-ancient tragedy.
-
-But this wasn't the only scene of mass death to be preserved here in the
-fossil record. A few kilometers away an earlier drought took a toll of
-many other animals. The little gazelle-like camel _Stenomylus_ tells the
-same story in scores of skeletons east of the _Menoceras_ burial ground.
-
-These graceful little camels may have died at the edges of their
-vanished water hole. The skeletons are mostly undisturbed except for a
-few pulled apart by meat-eaters. Scores of their dried out, mummified
-carcasses were buried about the same time as the rhinos on the river's
-dry bottom. Like the _Menoceras_, the camels lay there for millions of
-years, intact in their death poses, the muscles in the backs of their
-necks pulling their heads back sharply into an unnatural position. There
-they lay until men discovered them.
-
-Our imaginary journey into the past has reached its end. We have seen a
-day at Agate as it might have been 20 million years ago. We have watched
-the animals going about their daily lives during times of plenty and
-have seen it as it was later, when death's heavy hand left a magnificent
-fossil heritage. This unique place is a window into the past, a window
-through which we can look back at any time and observe life at Agate
-millions of years ago.
-
-
-                      Excavations at Agate Springs
-
-  The first fossils were collected in volume in 1904 by Olaf Peterson of
-  the Carnegie Museum in Pittsburgh. Excavations have continued, off and
-  on, to the present. As early as 1892, Erwin Barbour's student F. C.
-  Kenyon had retrieved a few bones from the site but their significance
-  was overlooked. Rancher James Cook first picked some up in the 1880s
-  and may have first noticed such deposits, without particularly
-  recognizing them, in the 1870s.
-
-  Other institutions soon joined Carnegie in extracting slabs of the
-  great _Menoceras_ bone-bed, and occasional _Moropus_ and _Dinohyus_
-  specimens. The University of Nebraska opened a new quarry in 1905.
-  Henry Fairfield Osborn, president of the American Museum of Natural
-  History and one of the greatest popularizers and exponents of
-  evolutionary science, and his chief preparator Albert Thomson began
-  work in 1907. F. B. Loomis of Amherst College discovered the nearby
-  _Stenomylus_ quarry the same year. Yale University's R. S. Lull soon
-  followed.
-
-  From 1911 to 1923 the American Museum became the main excavator at
-  Agate, but increasingly their attention was drawn elsewhere, including
-  the later Miocene Snake Creek Beds 20 miles to the south. There, for
-  awhile, great excitement centered around a worn tooth thought to be
-  from an early human ancestor until the tooth was proven to be from an
-  ancient peccary.
-
-  Until 1981, only occasional excavations for bonebed slabs and
-  _Stenomylus_ marked the next 50 years. Then, Robert M. Hunt Jr. of the
-  University of Nebraska reopened the main quarries and a little-known
-  side area, and found evidence of an extensive carnivore den of the
-  beardog _Daphoenodon_.
-
-  In some cases, individual fossil bones were removed one by one, a very
-  slow and painstaking process but when possible large blocks of
-  fossil-bearing sediments were removed and shipped to laboratories for
-  cleaning and analysis. The tools, chemicals, and special conditions
-  necessary to extract the best specimens and most complete information
-  are available only in a laboratory such as the one which is shown on
-  pages 40 and 41 at the Carnegie Museum in Pittsburgh, Pennsylvania, in
-  1905. Slabs from Agate Fossil Beds were taken there so paleontologists
-  could examine the evidence and figure out the past.
-
-  See pages 86-87 for a listing of museums with specimens from Agate
-  Fossil Beds.
-
-    [Illustration: Extracting a slab]
-
-    [Illustration: Members of Peterson's crew built a box around a slab
-    in the _Stenomylus_ quarry around 1908 in preparation for shipping
-    to the Carnegie Museum.]
-
-    [Illustration: With a team of horses, O. A. Peterson's field crew
-    moves dirt out of the _Stenomylus_ quarry around 1908. The boxes in
-    the foreground are resting on the quarry's lower bone layer. Several
-    specimens to the left have been strengthened with plaster for
-    shipment to Pittsburgh.]
-
-    [Illustration: Crates of prepared specimens had to be taken to
-    Harrison, 37 kilometers (23 miles) north of Agate for the rail trip
-    to the East. Note that the wagon is just a flat platform and that
-    the driver is using the largest crate as a seat.]
-
-    [Illustration: Paleological laboratory.]
-
-
-                     The Beginnings of Paleontology
-
-  Paleontology is the study of ancient life through the fossil remains
-  of that life. Today, there are thousands of museums, societies,
-  professional groups, and academic institutions around the world
-  devoted to this study. Fossil remains are still being dug out of the
-  ground in a number of localities, such as Dinosaur National Monument
-  in Utah, but by far the great bulk of fossils now being studied were
-  excavated during the last 100 years.
-
-  There are now about 250,000 known separate species of fossil plants
-  and animals. Biologists are still working to explore, find, and
-  classify all living species; they estimate that 4,500,000 species of
-  plants and animals are now living at our own brief moment in the
-  nearly five billion years of our planet's history. As you can see, the
-  fossils now known represent only a tiny fraction of all the plants and
-  animals that have ever lived. Yet a great deal is now known about even
-  the simple forms of life more than three billion years ago.
-
-  How has this come about? What has happened since the days of our
-  great-grandfathers to cause this vast increase in knowledge? Men must
-  have picked up and discussed fossils for tens or perhaps hundreds of
-  thousands of years. We have no way of knowing what the earliest men
-  thought about them. Their significance has been revealed slowly in the
-  way we tend to look at time, but perhaps not so slowly when we
-  consider how short a period man himself has been on Earth.
-
-  Lucretius, a Roman writer of the first century B.C., thought that the
-  Earth was very young. He interpreted the fossils known to him as the
-  remains of monsters that had grown out of the Earth just after it came
-  into existence. Evidently he had seen partial fossils and believed
-  them to be whole, because he postulated that the Earth had brought
-  forth creatures that lacked one or more limbs or other body parts.
-  Lucretius assumed, as have many others, that the varieties of animals
-  he knew of were fixed for all time and did not change. But he did
-  recognize the principle of evolution, that things change as time goes
-  on, in his description of human history.
-
-  Lucretius described four ages of human life, progressing from early
-  hunters up to the highly civilized life he knew under the Roman
-  Republic. His work was rediscovered during the European Renaissance,
-  when scholars once again began to inquire into the nature of seemingly
-  inexplicable things like fossils.
-
-  Toward the end of the 18th century the confusion over the importance
-  of fossils and their relative antiquity forced a scientific showdown.
-  For hundreds of years, fossil bones of extinct animals unlike any ever
-  seen had been turning up, often with tools nearby that appeared to
-  have been shaped by human hands. A growing feeling that the Earth and
-  therefore the fossils were very old indeed was a topic of frequent
-  discussion in Europe and in the New World, despite the assertion by
-  Archbishop Ussher a century earlier that the Earth was not quite 6,000
-  years old.
-
-  Explorers and scientists had found fossils in deep layers of rock
-  widely separated by other layers of rock, leading many of them to
-  conclude that now-extinct forms of life had existed before the
-  Biblical flood. A pioneer French paleontologist, Georges Cuvier, tried
-  to solve this dilemma in the late 1700s by postulating that there must
-  have been several worldwide floods before the one described in the
-  Christian Bible. Finally, this solution collapsed under the weight of
-  new evidence as more and more studies proceeded.
-
-  In the 1830s an English geologist, Sir Charles Lyell, popularized the
-  principle of uniformitarianism--the idea that processes we observe
-  now, such as the steady erosion of mountains, the gradual buildup of
-  silt as sediments in rivers, lakes, and oceans, have always occurred
-  since the origin of the Earth. This, he then reasoned, meant that the
-  Earth must be many millions of years old at least, instead of merely a
-  few thousand years old.
-
-  A wave of interest in fossils and their antiquity swept communities
-  around the world in the 1840s and 1850s. Americans interested in
-  science from Thomas Jefferson on had advocated the collection and
-  study of fossils, and a feverish race to build up study collections
-  got underway that lasted into the 20th century. Today, scientists
-  believe the Earth is more than 4.5 billion years old, its life more
-  than 3 billion years old.
-
-    [Illustration: Karl Von Linn�, 1707-1778, is known as Linnaeus after
-    the Latin form of his name. A Swedish botanist, he established a
-    hierarchical system for classifying plants and animals that is still
-    in use in a modified form. His organizing principle was the degree
-    of complexity of the organisms he studied. This resulted in a system
-    with seven levels: Kingdom, Phylum, Class, Order, Family, Genus, and
-    Species, in descending order from the broadest category to the most
-    specific. Students remember the system by the sentence "King Philip
-    Crossed the Ocean For Good Soup." Without realizing it, Linnaeus
-    prepared the ground for the evolutionists, who later were able to
-    demonstrate the gradual ascent of life forms from simple to complex
-    by using his scheme of classification.]
-
-    [Illustration: Jean-Baptiste de Lamarck, 1744-1829, a French
-    physician and ex-military man, founded the modern study of animals
-    without backbones and coined the term invertebrates to describe them
-    as a group. When his battle wounds forced him to take up a new
-    career, he studied botany and published a study of French plants. He
-    later turned to invertebrates, and between 1815 and 1822 published
-    the classic _Histoire naturelle des animaux sans vert�bres_. He
-    applied his vast knowledge of living invertebrates to
-    paleontological work, greatly enhancing the knowledge of fossil
-    invertebrates. Lamarck was also an evolutionary theorist, and he
-    believed that a single characteristic acquired by an animal during
-    its lifetime could be passed on to its descendants by heredity
-    (modern genetic theory was unknown at that time). He saw that
-    evolution must have taken a long time to occur, and he supported the
-    principle which has since become known as uniformitarianism.]
-
-    [Illustration: Georges Cuvier, 1769-1832, was a French anatomist and
-    paleontologist who specialized in the study of animals with
-    backbones, the vertebrates. He had a long and brilliant career as a
-    professor, eventually becoming France's minister of the interior in
-    1832. His skill as a comparative anatomist enabled him to understand
-    how vertebrate fossils should be reconstructed to form a complete
-    skeleton, and he was one of the first to use the small muscle scars
-    on fossil bones to reconstruct the extinct animal's musculature. His
-    classic work _R�cherches sur les Ossemens Fossiles de Quadrup�ds_
-    was published in 1812. He is known for his theory of a series of
-    natural catastrophes, each supposedly obliterating all extant life,
-    to account for the great variety of ancient fossils. This theory was
-    later supplanted by the theory of continuous evolution supported by
-    Darwin, Lyell, and others.]
-
-    [Illustration: Charles Darwin, 1809-1882, is today a household name
-    that is still invoked in controversy as it was more than a hundred
-    years ago. An extraordinarily patient and insightful biologist,
-    Darwin contributed the idea of natural selection, the "weeding out"
-    of unfit individuals and species, and described it as the guiding
-    principle of the evolution of life on this planet. His book _On the
-    Origin of Species by Means of Natural Selection_, published in 1859,
-    is the most important landmark in evolutionary studies. This was the
-    culmination of decades of work, leading to conclusions startlingly
-    similar to those of his fellow Englishman, Alfred Wallace. Darwin
-    knew nothing of the genetic principle of biological heredity and
-    variation, which has now assumed equal importance with natural
-    selection in the study of the evolution of life. For
-    paleontologists, Darwin's work meant they must look for transitional
-    forms of life and not content themselves with Cuvier's assumptions
-    that past life forms had been static and unchanging. During his
-    travels in South America, Darwin contracted a disease, now known as
-    Chagas' disease, and suffered intense pain and discomfort the rest
-    of his life. He died of a heart attack on April 19, 1882, and was
-    buried in Westminster Abbey in London a few days later.]
-
-    [Illustration: Charles Lyell, 1797-1875, revolutionized the study of
-    geology partly by publicizing the earlier work of James Hutton, who
-    died the year Lyell was born in Scotland, and partly by infusing the
-    science with his own highly disciplined point of view. His greatest
-    contribution was the firm establishment of Hutton's principle of
-    uniformitarianism, or uniformism, which became the foundation for
-    all modern geological work. Put simply, this is the principle that
-    the processes we see operating to form and shape the Earth today
-    have always operated in the past. Once this is admitted, it becomes
-    clear that past geological time is vast, not short, a truly stunning
-    notion for Lyell's time but a commonplace fact today. The first
-    volume of his _Principles of Geology_ was published in 1830; in his
-    later works he championed Darwin's own revolutionary point of view,
-    adding his own powerful arguments in support of the idea of natural
-    selection.]
-
-    [Illustration: Alfred Wallace, 1823-1913, was the co-originator,
-    with Darwin, of the principle of natural selection, or "survival of
-    the fittest." The main difference between the two was that Wallace
-    did not believe that natural selection explained things as well as
-    Darwin thought it did, which has been borne out to a large extent by
-    modern studies of genetic variation. Wallace worked in South
-    America, along the Amazon and Rio Negro rivers, and in East Asia. He
-    showed that the animals on either side of a line between Borneo and
-    the Celebes Islands are radically different in their makeup and
-    origin. Now known as "Wallace's Line," his work has been vindicated
-    by additional modern studies. Although Wallace did not become as
-    well known as Darwin, his brilliant, independent studies lent a
-    great deal of weight to the Darwinian view of evolution.]
-
-    [Illustration: _The largest divisions of geologic time are eras,
-    shown above in chronological order from the oldest on the bottom to
-    the most recent on top. The scale at left shows the relative
-    duration of each era. As the chart shows, geologists further divide
-    time into periods and, in the Cenozoic Era, into epochs. The
-    fossilization of animals in the Agate Springs area of Nebraska took
-    place in the Miocene Epoch. Adjustments to this time chart are made
-    as new data becomes available, so it should not be thought of as an
-    unchanging reference. This diagram is adapted from one in The
-    Emergence of Man series published by Time-Life Books._]
-
-                           Geologic Time Chart
-                 Period        Epoch    Time span (years before present)
-
-  Cenozoic    Quaternary    Pleistocene              10,000 to 2 million
-              Tertiary      Pliocene                      2 to 5 million
-                            Miocene                      5 to 23 million
-                            Oligocene                   23 to 34 million
-                            Eocene                      34 to 55 million
-                            Paleocene                   55 to 65 million
-  Mesozoic    Cretaceous                               65 to 138 million
-              Jurassic                                138 to 205 million
-              Triassic                                205 to 240 million
-  Paleozoic   Permian                                 240 to 290 million
-              Carboniferous                           290 to 365 million
-              Devonian                                365 to 410 million
-              Silurian                                410 to 435 million
-              Ordovician                              435 to 500 million
-              Cambrian                                500 to 570 million
-  Precambrian                                      570 to 4,500+ million
-
-
-                     The Geologic History of Agate
-
-Although the whole story of Agate Fossil Beds dates from the formation
-of the Earth four and one half billion years ago, only the last 600
-million years is known in detail. It was about 600 million years ago
-that many plants and animals began to have hard parts--parts likely to
-be preserved as fossils. The few fossils contained in older rocks are
-often folded, twisted, squeezed, and distorted so that their original
-character is all but erased. That isn't always the case, of course. Some
-of these old rocks, the Belt Series in Montana, look as though they were
-deposited only a few million years ago; they contain traces of algal
-colonies indicative of the generally simple life forms on the primitive
-Earth. The old rocks, deposited during the first four billion years of
-Earth's history, record the Precambrian Eons, spanning eight-ninths of
-geologic time.
-
-The evolutionary development of skeletal remains has aided in the study
-of geologic history. The last 600 million years have been divided into
-units for ease of discussion and comparison. The three largest divisions
-are the eras--Paleozoic (ancient life), Mesozoic (middle life), and
-Cenozoic (recent life). We are viewing all this from our vantage point
-at (what is now) the most recent episode of the Cenozoic.
-
-To begin at the known beginning, we only need go back to the start of
-the Paleozoic Era some 600 million years ago. No Precambrian, Paleozoic,
-or Mesozoic rocks can be seen around Agate, but we know from rocks found
-in comparable areas about what to expect under the surface at Agate:
-thousands of meters of sedimentary rocks, most of them laid down in an
-ocean. During the Paleozoic and most of the Mesozoic eras, up until
-about 70 million years ago, the west-central United States was covered
-by seas. The area now occupied by the Rocky Mountains was then a long
-north-south trough in which thick sediments collected. To the east, the
-present Great Plains area was the floor of a shallower sea. Sediments
-collected in the trough and on the sea bottom. Gradually, over a period
-of 530 million years, the sediments accumulated to a thickness of over
-2,100 meters (6,900 feet). A dynamic "give-and-take" process, this
-sedimentation was the result of periods when the sea rose and fell
-several times.
-
-If the Paleozoic sounds a little dull, it's because we haven't told the
-whole story. During the Paleozoic Era, all the major groups of organisms
-evolved. The seas swarmed with trilobites and shellfish of all kinds,
-some weird and fantastic and some very like those alive today. With them
-coexisted fish and sea-lilies, seaweeds and giant swimming "scorpions."
-For the first time, plants and then animals came out of the sea to live
-on the land. These events and creatures are preserved in Paleozoic
-rocks. The Mesozoic Era saw the development of mammals from reptiles,
-the rule of giant dinosaurs, and the beginnings of flight. Strange
-reptiles evolved and returned to the sea, or glided through the air on
-motionless wings. The Sundance Formation, deposited in the northern
-Rocky Mountains about the middle of the Mesozoic Era, is noted for the
-masses of bullet-shaped squid shells found in it. Water, land, and air
-were full of life.
-
-In the Middle Mesozoic, the trough drained and much of it became an area
-of swamp and tropical forest extending from Montana to southern Utah.
-This was the domain of our largest dinosaurs, giant reptiles whose bones
-were preserved in impressive numbers. Como Bluff and Bone Cabin,
-Wyoming; Morrison, Colorado; and Dinosaur National Monument and
-Cleveland, Utah, are the sites of quarries where many fine specimens of
-_Apatosaurus_, _Diplodocus_, _Stegosaurus_, and _Allosaurus_ have been
-collected. These caches of bones have made our large museums showplaces
-known throughout the world.
-
-During the last 65 million years of the Mesozoic, the trough fluctuated
-up and down. During much of that time a broad, shallow sea covered
-central North America from the Gulf of Mexico to the Arctic Ocean. The
-sea was filled with fish like the giant _Portheus_ (3.5 meters/11.5 feet
-long), with squid-like animals floating about in elaborate chambered
-shells, and with reptiles which had gone back to the water. Where there
-was a broad coastal plain, it swarmed with dinosaurs, the ones that make
-Lance Creek, Wyoming and Hell Creek, Montana famous collecting grounds
-for museum field parties. Yet at the end of the era the trough was a
-seaway again, and in the Agate area a final blanket of black mud, the
-Pierre Shale, was deposited in the sea.
-
-At the end of the Mesozoic Era a profound change came over the land. The
-trough, with hundreds of meters of sediments accumulated on its bottom,
-was drained and folded by pressures built up in the Earth's crust. To
-the south, the Colorado Plateau rose slowly and smoothly; to the north
-folding and faulting built complex mountain ranges. This uplift is
-called the Laramide Revolution because of the magnitude of the change it
-made on the face of the continent.
-
-At the beginning of the Cenozoic Era, about 65 million years ago, the
-Rockies and the Great Plains were slowly rising. Rains fell and rivers
-carried the water, wearing away the old sediments. Some sediments were
-carried west into the Pacific Ocean, or deposited on the land and
-covered over by new sediments. Some sediments remained within the
-Rockies, settling into basins during the early Cenozoic. Other sediments
-were carried east by the rivers, beyond the Great Plains and into the
-Mississippi Embayment. Mountain building and erosion tended to cancel
-out one another in the Rockies, preventing the mountains from reaching
-great heights. The mountain bases were perhaps no more than 300 meters
-(1,000 feet) above sea level, and the crests perhaps 600 meters (2,000
-feet) above that.
-
-Before long, the basins within the Rockies filled with sediments. The
-basins overflowed, and at last sediments began to cover the Great
-Plains. This was near the end of the Eocene Epoch, about 35 million
-years ago. Subtropical rivers, flowing sluggishly, rolled out over their
-banks and left their loads of silt and clay on the featureless plain.
-
-The oldest part of the blanket of sediments, the White River Beds,
-extended from Saskatchewan to Texas. Nearly 200 meters (650 feet) of
-muds, clays, silts, and river gravels were laid down during the 11
-million years of the Late Eocene and Oligocene Epochs. Magnificent
-exposures of these beds can be seen at Scotts Bluff National Monument in
-the valley of the North Platte, in Toadstool Park north of Crawford,
-Nebraska, and particularly in the Big Badlands of southwestern South
-Dakota.
-
-The kind of floodplain deposition characteristic of the Oligocene on the
-Great Plains ended about the beginning of the next epoch, the Miocene.
-In Nebraska the process continued, but eventually erosion began wearing
-away the accumulated sediments. The land to the west was uplifted a
-little, and the streams flowed off the high ground fast enough to cut
-down into what they had just deposited. On this eroded surface, the
-layers of tan silts, fine sands, and clays known as the Gering Formation
-were deposited.
-
-On top of the Gering Formation, in the Late Oligocene, is the Monroe
-Creek Formation, the oldest formation actually exposed in the Agate
-area. This formation is named for exposures in Monroe Creek Canyon north
-of Harrison, Nebraska, and may be up to 75 meters (245 feet) thick. You
-can see a little of the Monroe Creek Formation's pinkish silts and
-volcanic glass shards exposed in the valley of the Niobrara River. Where
-it is more exposed by erosion than at Agate, the Monroe Creek Formation
-forms magnificent cliffs along the Pine Ridge and similar areas of high
-ground. The best local examples are at Fort Robinson State Park between
-Harrison and Crawford, Nebraska. A close look can be obtained in Smiley
-Canyon just west of the fort, where old U.S. Highway 20 is maintained as
-a scenic drive.
-
-After the Monroe Creek interval, near the end of the Oligocene,
-deposition of the famous Agate Fossil Beds began. Geologists have named
-this sequence of grayish silts and sands the Harrison Formation for its
-occurrence near Harrison, Nebraska. A short interval of erosion
-separates it in some areas from the Monroe Creek Formation below, and
-its coarser sands indicate increasing uplift of lands to the west. Wind
-played a smaller role in deposition than in Monroe Creek times, though
-that is certainly not true at the _Stenomylus_ quarry. The Harrison
-Formation was the last of the truly widespread deposits seen in the
-Miocene of the Great Plains. Many rivers flowing eastward from the
-Rockies contributed sands to Wyoming, South Dakota, and Nebraska.
-
-Generally the Harrison Formation and the overlying Marsland Formation
-are only moderately fossiliferous, but along the Niobrara River here at
-Agate, Nebraska, the accumulation of rhinoceros and camel skeletons is
-one of the wonders of the fossil world. Here, thousands of animals
-perished in two droughts which coincided with conditions perfect for
-preservation. About two kilometers (1.2 miles) east of the Monument
-headquarters the dried-out, mummified bodies of perhaps a hundred or
-more little camels, _Stenomylus hitchcocki_, were buried under windblown
-sand during the first drought.
-
-Shortly after the camels were buried there was a brief period of erosion
-and then the Marsland Formation began to be deposited. Named for a
-little village east of Agate, the Marsland Formation consists of basal
-river channel deposits followed by about 45 meters (150 feet) of
-wind-blown tan-and-gray sands. It is in one of these river channel
-deposits that the Agate rhinoceros quarries are located.
-
-The second drought occurred early in Marsland times and literally
-hundreds of the little rhino, _Menoceras_, were preserved when their
-carcasses were broken up by a reborn river and buried like a mat of
-jackstraws in a river lake.
-
-After Marsland times there was more erosion, in some places by rushing
-streams that cut down 91 meters (300 feet) through soft sediments, to
-the top of the Monroe Creek Formation. In these channels the
-Runningwater Formation was deposited because it filled in the stream
-valleys and wound around the high spots. This channel deposit is not
-found everywhere, but it does have an equivalent in southwestern South
-Dakota. Other deposits of similar age are found in many parts of the
-Great Plains, and they contain fossil animals like those found in the
-Runningwater Formation.
-
-The turbulent streams which deposited the Runningwater Formation were
-flowing off newly uplifted land to the west. This was the beginning of
-the most recent major uplift of the Rocky Mountains, and it signalled a
-great change in the pattern of deposition on the Great Plains. No longer
-would broad blankets of sediments be deposited by sluggish streams
-originating in the low, broad warp of the Rockies.
-
-This latest uplift is called the Rocky Mountain Revolution. It brought
-on a period of alternating cycles of deep channel cutting and stream
-deposition. Floodplain deposits were restricted to narrow ribbons in
-river-cut valleys. Even more important than the changes in deposition
-was the effect of this uplift on the climate. As the Rockies began to
-rise to their present height, the climate became increasingly arid and
-the tree-dotted savanna of the old Great Plains gave way to grasslands.
-
-Several kilometers south of Agate, the Sheep Creek Formation was laid
-down during the Middle and Late Miocene. The appearance of the grazing
-horse _Merychippus_ in these channel and floodplain deposits marked the
-establishment of the grasslands as the newly dominant ecosystem of the
-Great Plains. At that time the "modern" fauna began to replace the old,
-and new patterns of life were established.
-
-Again rejuvenation of the stream system, probably reflecting further
-uplift in the west, started another erosional interval that began to
-wash away the beds just deposited. When deposition followed in the Late
-Miocene, a new series of channel and floodplain deposits, the Lower
-Snake Creek Beds, was laid down. On them was deposited the Upper Snake
-Creek Beds, and together they span most of the Late Miocene and the
-Early and Middle Pliocene epochs. Harold Cook collaborated with W. D.
-Matthew of the American Museum of Natural History, publishing important
-papers on the numerous finds from these fossiliferous deposits. Animals
-new to science are still being discovered in the Snake Creek Beds.
-
-After Snake Creek times, the area immediately around Agate was left out
-of the mainstream of events on the Great Plains. The continuing uplifts
-of the Rocky Mountains were no longer recorded here in cycles of
-downcutting and channel deposition. If the cycles continued here, all
-traces have now been washed away--an unlikely possibility. The view from
-the high plains above the valley of the Niobrara River reveals only the
-rolling surface of the pre-Runningwater deposits.
-
-A more complete record is found in the river terraces of major streams,
-the North Platte to the south and the White and Cheyenne Rivers to the
-north. These terraces tell the story of continuing uplifts. To the
-south, east, and northeast of the Platte the record is also written in
-fossil bones, but these are outside the scope of our story.
-
-Northwestern Nebraska, northeastern Colorado, southeastern Wyoming, and
-southwestern South Dakota today remain a promised land for
-paleontologists studying mammal life in North America during the middle
-and later Cenozoic Era. The fossil deposits in the Agate area are
-surpassed in importance only by the Late Eocene and Oligocene deposits
-of the Big Badlands and Pine Ridge in South Dakota.
-
-
-                     Ecology: Change and Adaptation
-
-During the Age of Mammals (the Tertiary Period), three major
-environments dominated western Nebraska. The first of these occurred
-during the Paleocene, Eocene, and Oligocene epochs. This was a forest
-system where trees were the major component of the flora. Meadows were
-found only in scattered areas and can be considered a minor element.
-There is no geologic or paleontologic record of the Paleocene and Eocene
-in the Agate area, but when our present knowledge of the early Tertiary
-Rocky Mountain floras is projected eastward a bit, a predominantly
-forested landscape is indicated.
-
-It is in some ways ironic that while the Oligocene land-laid sediments
-of southwestern South Dakota, western Nebraska, southeastern Wyoming,
-and northeastern Colorado contain one of the best vertebrate fossil
-records in the world, the plant record is almost non-existent.
-Unfortunately the groundwater chemistry that was so right for the
-preservation of bones was hostile to the preservation of plants.
-Hackberries (_Celtis_) and walnuts (_Juglans_) are the only recorded
-plant species from the Oligocene in this very large area. Because these
-are such widespread and climatically tolerant types, they tell us almost
-nothing about the environment. Indications of the flora at Agate may be
-obtained, however, from the extraordinary Late Eocene flora found at
-Florissant, Colorado, south of Denver. Although this deposit does
-contain some upland species, it generally indicates a warm temperate
-forest including such things as horsetail rushes, ferns, cattails,
-grasses and sedges, poplar, willow, birch, oak, elm, serviceberry,
-sycamore, maple, sumac, and--of course--hackberries and walnuts.
-
-During the Early Miocene, slightly changed climatic conditions brought
-about by minor uplifts in the Rocky Mountain area transformed the
-immediate area of western Nebraska into a savanna of mixed trees and
-grasslands. This second system probably reached its climax just about
-the time the Harrison Formation was being laid down during the Early
-Miocene. This was a savanna with scattered clumps of trees, gallery
-forests, and grasslands. The modern world's richest and most diverse
-fauna of hoofed mammals can be found on the savannas of east Africa. On
-the savannas, grazing and browsing (grass eating and leaf eating)
-adaptations of the larger plant eaters are represented.
-
-    [Illustration: 35 million years ago]
-
-    [Illustration: 25 million years ago]
-
-    [Illustration: 15 million years ago]
-
-    [Illustration: 35 million years ago, life along the Niobrara River
-    near Agate would have appeared something like this. Two oreodons (1)
-    have startled an alligator (2) and two hippopotamus-like
-    _Aepinacodons_ (3) along the river bank. Climbing a tree is an
-    opossum (4), one of the oldest forms of life in the world today.
-    Note the many familiar trees and plants, particularly the
-    cottonwood, willow, beech, dogwood, and cattail.]
-
-    [Illustration: 25 million years ago, a savanna dominates the Agate
-    landscape. Copses of oak and pine are interspersed with open
-    grassland. In the foreground are several _Parahippus_ (1), an
-    ancestor of today's horse, while _Oxydactylus_ camelids (2) move
-    away into the distance and, overhead, a hawk (3) searches for
-    rodents.]
-
-    [Illustration: 15 million years ago, the Agate landscape has changed
-    to an open prairie. A small herd of _Merychippus_ horses (1) races
-    toward the arroyo in the distance, narrowly escaping ambush by a
-    large, leopard-like cat known as _Pseudaelurus_ (2). A few
-    cottonwoods, elms, sycamores, and willows grow along the river, but
-    cedars predominate in the arroyo in the middle ground, where they
-    are protected from winds that sweep across the plains. Though the
-    animals have changed, the landscape is essentially like this today.]
-
-In western Nebraska the savanna environment lasted for only a very short
-time, in a geologic sense, before it gave way to a wave of advancing
-grasslands, the third phase of Tertiary environment in the area.
-Tallgrass prairie such as that still found 325 kilometers (200 miles)
-east of Agate a century ago must have been first among the grassland
-types. Trees, when present at all, were restricted to the borders of
-streams. Then as the climate became even more arid the prairie or tall
-grass retreated eastward, while the forest moved before it even farther
-to the east and south, and the modern shortgrass of the plains took its
-place. Today Agate lies in one of the valleys whose rivers are slowly
-dissecting the High Plains.
-
-The modern plains are dominated by short, curly, sodforming buffalo
-grass, a plant well adapted to the area's light rainfall, periodic
-droughts, low humidity, rapid evaporation, and high winds. The dominant
-vertebrate animals are burrowers and grazers, and dogs are the primary
-carnivores. Hoofed animals such as the pronghorn, the ultimate in the
-running and bounding adaptation; jumpers and hoppers, such as
-jackrabbits and jumping mice and rats; and burrowing mound builders,
-such as the prairie dog (a large ground squirrel), the pocket gopher,
-and harvester ants typify the major occupations of plains animals.
-
-The environmental type seen on the Great Plains of North America is
-elsewhere best developed in the Pampas of Argentina, the Puztas of
-Hungary, the Veld of Africa, and the Steppes of Russia. In the climatic
-classification of the climatologist and geographer, the term _steppe
-climate_ is applied to all these areas, the Great Plains included.
-
-If the savanna is the halfway station between forests and grasslands,
-then the fossil fauna of the Early Miocene at Agate was a fauna in the
-beginning of a serious transition. In the vicinity of Agate, the fauna
-from the Late Oligocene was dominated by mammals with low-crowned teeth.
-The crown is that part of the tooth which is above the roots and exposed
-beyond the gums. Among the herbivores, the browsers can live a long life
-with low-crowned teeth. But when any appreciable amount of grass,
-particularly the short, tough grass of the plains and the abrasive dirt
-and sand that accompanies it, becomes part of an herbivore's diet, there
-is a great increase in the rate of tooth wear. Teeth which have evolved
-for browsing quickly wear down to the gums and the individual dies of
-starvation.
-
-Accompanying the development of extensive grasslands came the evolution
-of the high-crowned tooth. This process begins simply with the growth of
-a taller crown that erupts completely from the gum right after the milk
-or deciduous teeth fall out. Another step is the development of a longer
-or higher crown most of which is held in the jaw and then slowly pushed
-out as the chewing surface is worn down. This is the "mechanical pencil"
-effect in that the "lead" may be pushed out as needed. Teeth of this
-type are perhaps best seen in the later horses. From their appearance in
-the Late Paleocene until the end of the Early Miocene, all horses had
-low-crowned teeth. With these they could chew the soft leaves and twigs
-of trees and shrubs, first in the forests and later in the groves and
-clumps on the developing savanna. By Early Miocene (i.e., Harrison)
-times, there was only a slight increase in crown height in _Parahippus_,
-but it had evolved an increasingly complicated crown pattern which
-served to lengthen the time it took for the tooth surface to wear down
-flat. With the greater aridity of the changing climate, the teeth of
-_Parahippus_ became higher and higher crowned, as the individuals with
-the best teeth lived longest and had greater opportunity to produce
-offspring than those with lower-crowned teeth. In some species, the
-tooth material called cement, which ordinarily covers the roots of the
-teeth, began also to cover the enamel of the crown and give additional
-wearing strength to the teeth. Soon after the beginning of the Middle
-Miocene, two species had developed cement-covered teeth whose crowns
-were high enough to warrant placing them into two new genera of horses,
-_Merychippus_ and _Protohippus_. These forms, first recognized in the
-Lower Sheep Creek Beds in the Agate area, were the first horses to use
-the mechanical-pencil effect, having cheek teeth that continued to rise
-out of the jaw as the tooth was worn down. _Merychippus_ later gave rise
-to a line of three-toed horses, which lived on into the Pliocene;
-_Protohippus_ gave rise to a line which ultimately led to _Equus_, the
-modern horse.
-
-The ultimate in high-crowned teeth occurs when roots do not ever form at
-the base of the tooth; additional crown material is constantly added at
-the bottom of the tooth as it is pushed out of the gum. This type of
-growth resembles the foundry process of extrusion, where metal or
-plastic is pushed through a mold to produce a continuous strand. This
-extreme development is seen in the incisors or gnawing teeth of beavers,
-gophers, and other Late Oligocene rodents, and in the grinding teeth of
-only a few forms. The cheek teeth (the grinders) of modern pronghorns
-(artiodactyls), gophers (rodents), and rabbits (lagomorphs) are typical
-of this kind of development today. During the Middle Oligocene, only the
-strange little fox terrier-sized, flat-headed oreodon _Leptauchenia_,
-the tiny "deer" _Hypisodus_, and the rabbit _Palaeolagus_ had mechanical
-pencil-type teeth. Some of the rhinos then had fairly tall crowns, but
-these don't really qualify as high-crowned teeth. It was not until later
-on, when the grasslands took over completely, that high-crowned teeth
-really came into their own.
-
-There was no dramatic change in the fauna at the beginning of the
-Miocene, and many Oligocene genera carried over into the new epoch. Most
-of the Eocene hold-overs, primitive animals that had survived in the
-extensive forests, became extinct when the forests began to retreat; but
-for the most part the record continued undisturbed. This is to be
-expected where the deposition of sediments continues without
-interruption. (Remember that the epochs, periods, and eras were
-originally based on breaks in the European sedimentary record reflecting
-local events which would not necessarily show up in North America's
-sediments.)
-
-By the time the Harrison Formation was deposited, the development of the
-halfway world of the savanna was beginning to affect the fauna. Although
-the Oligocene and the very earliest Miocene mammal faunas were highly
-varied and rich in types of animals, much of this was due to the
-continued presence of primitive and archaic forms, and to the explosive
-development of rhinos and oreodons. With the savanna becoming the
-dominant landscape, the shift to grazing and away from browsing became
-evident. Or, at least, the presence of animals that both browsed and
-grazed was indicative of changing times. As was mentioned earlier,
-grazing and burrowing are characteristics of plains herbivores. In such
-a transitional period we would expect to find an increase in burrowers
-and grazers as grasslands became more common.
-
-
-                          Evolutionary Change
-
-  Animal species respond to environmental changes in a variety of ways.
-  Simply put, some species die off, some adapt physically, and some move
-  to a different habitat. On the next few pages are examples showing how
-  three species responded to long-term environmental changes in the area
-  around Agate Fossil Beds. The _Stenomylus_ line died off; _Miohippus'_
-  evolutionary line remained a grazing animal but changed physically
-  over the years, eventually becoming the modern horse; and the
-  _Palaeocastor_ line moved from land to water, gradually evolving into
-  the beaver.
-
-  Each of these three animals is portrayed here with partial skeleton,
-  musculature, and outer skin to help you see its general composition
-  and to emphasize certain physical features that developed in the
-  species over time. Paleontologists, of course, work this way. From
-  fragments and bones they reconstruct full skeletons, and from surmises
-  about muscular structure, often based on present-day animals, they
-  project the appearance of the animal. The artist, in this case Jay
-  Matternes, then brings together these bits of evidence to give us a
-  picture of life long ago.
-
-
-                                  Stenomylus
-
-A small, gazelle-like camel similar to the present-day gerenuk of
-  Africa. _Stenomylus_ is the second most common animal found in the
-  fossil beds at Agate. _Stenomylus_ had hard hooves like modern
-  antelopes and deer, unlike modern camels which have flesh-padded feet
-  adapted to desert terrain. The three-hued coat is inferred from the
-  coat of the modern gazelle, a similar form in adaptation.
-  _Stenomylus'_ evolutionary line eventually died out in North America
-  at the end of the Pleistocene. No one knows why both camels and horses
-  died out on this continent.
-
-            The distance between grid lines represents five centimeters.
-
-    [Illustration: 1 The ears moved in a parallel fashion, not
-    independently; the parallel movement is inferred from modern
-    llamoids, to which _Stenomylus_ is related.
-
-    2 _Stenomylus'_ musculature was adapted for high-speed running,
-    similar to the present-day pronghorn.
-
-    3 The back structure suggests that _Stenomylus_ would have made
-    short, choppy leaps, not the graceful, arcing leaps of a modern
-    impala.
-
-    4 Limbs were long in proportion to the body, allowing the animal to
-    run with great speed.
-
-    5 _Stenomylus_ had a hard, chitinous hoof, an adaptation for greater
-    running speed, and for sure footing on rough terrain.]
-
-
-                               Miohippus
-
-Over the last 60 million years the horses have evolved from small,
-terrier-sized animals to the diversity of size we know today, from the
-huge Clydesdales to the diminutive Shetland ponies. The three-toed early
-horse known as _Miohippus_ was about the size of a sheep. The
-descendants of _Miohippus_ apparently went in two directions in their
-evolution: One group continued to be forest-grazing, three-toed horses
-that eventually reached the size of modern horses but died out later.
-The other group, through such intermediate forms as _Parahippus_, became
-grassland forms that led eventually to the modern one-toed horses.
-Horses became extinct in North America at the end of the Pleistocene,
-but no one knows why. They continued to evolve on other continents and
-were re-introduced in historic times.
-
-            The distance between grid lines represents five centimeters.
-
-    [Illustration: 1 The back was straighter and stiffer than in earlier
-    horses, partly because of the increasing size of the animals and
-    partly to allow sustained open-plains running.
-
-    2 Limbs were long in proportion to the body, an evolutionary trend
-    in the horses for speed in open-plains running, rather than darting
-    about in forests.
-
-    3 Most of the weight of the animal was on the middle toe, which has
-    become a single toe in modern horses. This is an adaptation for
-    endurance and stability in open grasslands.
-
-    4 The upright mane is a primitive horse characteristic; wild horses
-    today have reverted to this trait.
-
-    5 The coat is shown as striped, a probable holdover from earlier
-    horses that dwelled in forests, where a striped coat would provide
-    camouflage.
-
-    6 A large, deep mandible supported teeth adapted to grazing and the
-    grinding of grasses and other wild plants. The teeth were
-    deep-rooted and continuously erupted as the surface was worn down by
-    the grit and dirt that came with the large quantities of plant food
-    consumed daily.]
-
-
-                              Palaeocastor
-
-_Palaeocastor_ was an ancient beaver whose mode of life was like that of
-a modern prairie dog--land-oriented instead of water-oriented.
-_Palaeocastor_ was small, about 12 centimeters (5 inches) high, and
-about 30 centimeters (12 inches) long. Its fossilized spiral burrows,
-called _Daemonelix_, survive to tell us what its habitation was like, a
-feature unique to _Palaeocastor_ among all the fossil beavers. The
-_Daemonelix_ shown here dwarfs a member of Olaf A. Peterson's field crew
-from the Carnegie Museum. The bones of a _Palaeocastor_ and one of its
-predators were found at the bottom of one such burrow, helping to prove
-that _Palaeocastor_ was responsible for making these corkscrew holes in
-the ground.
-
-            The distance between grid lines represents five centimeters.
-
-    [Illustration: 1 The powerful jaw and musculature allowed for
-    grazing on grasses and other plants, as well as masticating. The
-    teeth were deep-rooted and would continue to erupt as the surface
-    was worn down.
-
-    2 The complex musculature supported the use of the forelimbs in
-    burrowing. _Palaeocastor_ had a collarbone or clavicle, like us, for
-    greater agility in using the forelimbs.
-
-    3 The forelimbs were adapted to burrowing in the ground.
-
-    4 The tail is like that of a modern burrowing rodent, such as a
-    muskrat, whereas the modern beaver has a different, very specialized
-    tail.]
-
-    [Illustration: Daemonelix]
-
-A grazing animal is fairly easy to recognize, but how can we recognize a
-burrower? Some have radically adapted limbs and claws. Obvious cases are
-the common garden mole and the armadillo. The mole has powerful
-attachments for the muscles of the upper arm on the humerus, a bone so
-flattened that its width has come to match its length. Moles also have
-long, broad digging claws. The armadillo, which is also a digger but not
-a burrower in the same way a mole or a gopher is, has large curved claws
-for digging. Moles did start to become quite common in the Late
-Oligocene, so we can assume that a good burrowing environment was
-present.
-
-Another group which became extraordinarily common in the Late Oligocene
-of western North America was that of the ancestral pocket gopher. Direct
-proof that this group actually burrowed does not exist, but the
-abundance of fossil gophers suggests that they might have lived
-underground in colonies.
-
-A real surprise at Agate is the number of beaver burrows. The famous
-_Daemonelix_ or "devil's corkscrew" attests to the dense population of
-_Palaeocastor_. By that relatively advanced stage of beaver evolution,
-the animals might be expected to behave like the modern-day muskrat,
-perhaps digging dens along stream borders and spending some of their
-time in the water. The presence of skeletons in the spiral burrows,
-however, indicates that _Palaeocastor_ was primarily a burrower, one
-which perhaps lived very much like our present-day prairie dog. Despite
-that, there is no apparent structural modification to indicate burrowing
-abilities.
-
-Changing environmental conditions were pushing _Palaeocastor_ toward
-extinction in the Early Miocene. The disappearance of that ancient
-beaver, while not unusual, presents a problem for the careless observer
-who might assume that ancient animals behaved like their modern
-counterparts. The burrowing beavers of Miocene Agate certainly have no
-modern counterparts.
-
-While we can delineate in a general way the prehistoric life of Agate,
-we can't describe the past in any detail. Plants most directly reflect
-the effects of climate--and plant fossils are absent at Agate. As the
-base of the food chain, plants carry the influences of climate on to the
-plant-eating animals. From the numerous animal fossils found at Agate we
-have learned most of what is known about the environment of that time.
-Sediments tell a good part of the story, and floras from other
-localities help, but much of Agate's ancient ecology must be inferred
-from the bones.
-
-Today, standing on the porch of the visitor center or walking along the
-path to University and Carnegie Hills, visitors find themselves in the
-midst of the shortgrass prairie. Five distinctive plant communities
-share this prairie, coexisting in a dynamic relationship which depends
-upon local climate variations.
-
-Even to the untrained eye, it is evident that the basic short-grass
-pattern has been modified by the shape of the land and by the Niobrara
-River. In the stream valley, along the tributaries, and on shaded
-north-facing slopes, the shortgrass community is mixed with taller
-grasses. If a dry cycle began, the short grasses would take over the
-whole area by migrating downslope from the exposed prairies. Of interest
-is the fact that over-grazing by either domesticated or wild animals
-will have the same effect as a dry period in that taller grasses will be
-replaced by short ones.
-
-Let's examine the five communities present today so we can appreciate
-the complexity of relationships between living things and the earth upon
-which they depend.
-
-First, we can begin in the Niobrara River itself. The river's
-water-dwelling plant inhabitants include algae, which grow underwater.
-
-Between the river and the dry ground is a second community--the
-marsh--which is often more wet than dry. The marsh has its own
-characteristic plant association. Most familiar are the cattails, mints,
-and willows, but just as important ecologically are arrowleaf, rush
-sedge, marshweed and blue verbena. These are moisture-loving plants that
-thrive on being thoroughly soaked during the wet part of the year.
-
-Beyond the marsh on the valley floor is a third community. Here the
-water table (the top of the saturated soil and rock zone) is close
-enough to land surface that the plants can easily send their roots down
-into the saturated zone. Here, in what the plant ecologists call the
-"sub-irrigated floor plain" we find a mid-grass community. Eighty-five
-percent of the vegetation is slender wheatgrass. Its wheat-like heads
-may, under favorable conditions, grow to a height of one meter (three
-feet). At Agate it is seldom over knee high. Kentucky bluegrass takes
-care of another 10 percent of the plant population. Imported from Europe
-as a pasture grass in the 1600's, it spread so rapidly that it often
-beat the settlers onto new land as they moved westward. The remaining
-five percent includes imported redtop and such native grasses as
-switchgrass, foxtail barley, little bluestem, prairie cordgrass, and
-inland saltgrass. Wildflowers such as Flodmon thistle, yarrow, heath
-aster, salsify, and blue-eyed grass complete the community.
-
-Moving farther away from the stream, we rise up onto terraces within the
-valley. These terraces represent levels where the stream paused in its
-downcutting and cut sideways for awhile. At a drier level, on deep,
-well-drained sandy soils, they support the fourth or mixed-grass
-community.
-
-No exotics have yet appeared in this plant community. The grasses
-include prairie sandreed, sand bluestem, blue grama, needle-and-thread
-grass, and Indian ricegrass. Wildflowers include the prominent phlox,
-penstemon, and lupine. Unwelcome (to man and his grazing animals) is
-_Astragalus_, the selenium-concentrating plant better known as loco
-weed. The brittle prickly pear and spiderwort cactus are found here too.
-
-At higher levels in the terrace community, slightly steeper slopes and
-shallower soils cause some change in this mixed-grass assemblage. Here
-the dominant grasses are little bluestem, threadleaf sedge,
-needle-and-thread grass, and blue grama. Lupine disappears, and common
-pricklypear becomes the only cactus. In this community is found the
-yucca, its flowers a beautiful soft yellow in season and its spiny
-leaves painful at any time of the year. Avoid this plant; yucca spines
-break off under the skin and soon cause irritating festers. The yucca
-moth, often seen flying around the yucca seed pods, lays eggs in the
-plant's lemon-sized fruits. Inside the fruit are long rows of flattened,
-wedge-shaped seeds. When the yucca moth eggs hatch into caterpillars,
-they eat their way through the seeds, killing them. On the other hand it
-is the yucca moth with its long tongue that is solely responsible for
-pollinating the yucca flower! If you find a yucca fruit in early summer,
-you can (elsewhere than in the park) slice through it and see the
-caterpillars at work.
-
-On the high bluffs and overgrazed terraces is the fifth community, the
-short grass. This community too can be divided into two slightly
-different parts. The bluffs support blue grama grass, needle-and-thread
-grass, and Sandberg blue grass. Flowers and shrubs include _Eriogonum_,
-brittle pricklypear cactus, pepperweed, penstemon, broom snakeweed,
-fringed sagewort, and yucca. The other part of this community, the
-overgrazed terraces, have threadleaf sedge, needle-and-thread grass, and
-blue grama. Except for the familiar penstemon, all the flowers are
-restricted to this community. Gronwell, menzania, and bee plant are
-indicators of overgrazing.
-
-Certain cyclical variations are characteristic of these plant
-communities. First, the shortgrass and mixed-grass areas ebb and flow
-with changing moisture conditions from year to year. Second, grass
-populations change with the seasons. Cool-season grasses (foxtail
-barley, Indian rice grass, Kentucky bluegrass, needle-and-thread grass,
-Sandberg blue grass, and slender wheatgrass) flourish during spring and
-fall. During the warm summer the blue grama, inland saltgrass, little
-bluestem, prairie cordgrass, prairie sandreed, and switchgrass
-predominate. This natural adaptation to seasonal conditions uses the
-greatest potential of the growing season and at the same time provides
-species that will flourish in both wet and dry cycles.
-
-After reading this last section, you might look back at the section on
-Early Miocene ecology. Comparison reveals that a great deal of
-information can be obtained by examining living plants. In contrast, the
-lack of fossil flora from the Early Miocene at Agate has resulted in a
-scarcity of ecological information from that early epoch. Scientists
-begin their reasoning by such comparisons; you can begin your own
-exploration of the past in the same way.
-
-
-
-
-                         3    Guide and Adviser
-
-
-    [Illustration: Ask a ranger for directions to the protected example
-    of a Devil's Corkscrew, the fossilized burrow of a small,
-    beaver-like animal called _Palaeocastor_. See pages 68-69 for more
-    information about this interesting animal.]
-
-
-                           Visiting the Park
-
-
-                        Contents of This Section
-
-  Visiting the Park                                                    77
-      Location
-      Area
-      Climate
-      When to Visit
-      Visitor Center
-      Activities
-      Camping
-      Nearby Accommodations
-      Transportation
-      Establishment Date
-      Address
-      Access
-  Protection                                                           80
-      Park Regulations
-      Safety Tips
-  Birding Along the Niobrara                                           81
-      Taking the Annual Count
-  Collections of Agate Springs Fossils                                 86
-  NPS Areas With Fossil Exhibits                                       88
-      Badlands
-      Dinosaur
-      Florissant
-      Fossil Butte
-      Petrified Forest
-      John Day
-      Hagerman
-  Nearby National Parks                                                90
-      Badlands
-      Devils Tower
-      Fort Laramie
-      Jewel Cave
-      Mount Rushmore
-      Scotts Bluff
-      Wind Cave
-  Not So Nearby National Parks                                         92
-      Bighorn Canyon
-      Little Bighorn
-      Rocky Mountain
-      Theodore Roosevelt
-  Armchair Explorations                                                93
-
-
-                                   Location
-
-Northwestern Nebraska 69 kilometers (43 miles) north of Scottsbluff
-along the Niobrara River.
-
-
-                                  Area
-
-1,116 hectares (2,762 acres).
-
-
-                                Climate
-
-Temperatures range from winter lows of -38� C (-36� F) to summer highs
-of 39� C (101� F). Winter temperatures average 1� C (33� F), and winter
-snow averages 60 centimeters (2 feet) for the whole winter. However,
-snowdrifts can be much higher. Summer nights are cool, with temperatures
-averaging 10� C (50� F). Average annual precipitation is 41 centimeters
-(16 inches), with most precipitation in April and May.
-
-
-                             When to Visit
-
-Most people go to the park some time between June and August, but you
-can avoid the high summer temperatures by visiting in the spring, fall
-or--if you don't mind the cold and snow--in the winter. Spring can be
-blustery, but the fall is usually dry and the days are cool. Check ahead
-on local weather conditions if you plan a winter visit. Museums and
-tourist attractions in nearby Fort Robinson are open Memorial Day to
-Labor Day.
-
-
-                             Visitor Center
-
-A ranger is on duty to help you and answer your questions. Fossil
-exhibits and part of James H. Cook's personal collection of Indian items
-are on display in the visitor center, and publications about the park,
-paleontology, and history are on sale.
-
-
-                               Activities
-
-A trail from the visitor center takes you on a tour to both University
-and Carnegie Hills, with an interpretive display at each. The roundtrip
-distance is three kilometers (two miles) and takes about one hour. You
-may fish for German brown and rainbow trout in the Niobrara River if you
-have a Nebraska fishing license. The park has several tables for
-picnickers.
-
-
-                                Camping
-
-The park has no camping facilities, but there are state campgrounds near
-Harrison and near Fort Robinson, Nebraska, and a commercial campground
-on Nebr. 26 between Mitchell and Scottsbluff, Nebraska.
-
-
-                         Nearby Accommodations
-
-Hotels, motels, food stores, outdoor supply stores, and restaurants are
-available in Scottsbluff, Nebraska. A motel, restaurant, gas station,
-and grocery store are in Mitchell, Nebraska, 55 kilometers (34 miles)
-south of the park. There are a motel, food store, drugstore, and
-restaurant in Harrison, Nebraska, 37 kilometers (23 miles) north of the
-park, and there are motels and restaurants at Fort Robinson, Nebraska,
-37 kilometers (23 miles) east of Harrison, or 74 kilometers (46 miles)
-northeast of the park.
-
-
-                             Transportation
-
-Buses--The nearest bus connections are in Scottsbluff, Nebraska.
-Airport--Scottsbluff, Nebraska, has an airport served by a scheduled
-commercial airline. Rentals--Cars may be rented at the airport or at car
-rental agencies in Scottsbluff.
-
-
-                       Establishment of the park
-
-June 5, 1965.
-
-
-                            Mailing Address
-
-
-  Agate Fossil Beds
-  National Monument, 301 River Road,
-  Harrison, NE 69346.
-
-
-                                 Access
-
-    [Illustration: To reach the park from Scottsbluff, Nebraska, take
-    Nebr. 26 west to Mitchell, then Nebr. 29 north to the park. From
-    Fort Robinson, Nebraska, take Nebr. 20 west to Harrison, then Nebr.
-    29 south to the park.]
-
-                     [Illustration: Plains states]
-
-
-                               Protection
-
-    [Illustration: The trail from the visitor center takes you across
-    the Niobrara River, up University Hill to the fossil layer, then to
-    the fossil exhibit on Carnegie Hill, and back to the visitor center.
-    The walk takes about one hour.]
-
-    [Illustration: Two fishermen try their luck in the Niobrara.]
-
-
-                            Park Regulations
-
-To ensure your safety and to protect the park's natural and historical
-resources, several regulations have been established by the National
-Park Service. Collecting of fossils, rocks, plants, or other objects is
-not permitted. Please be sure to leave everything as you find it along
-the trails and throughout the park for others to enjoy. If you have any
-questions about park regulations and policies, please ask the staff. The
-rangers are here to help you and to enforce the regulations.
-
-
-                              Safety Tips
-
-Though snakes are not prevalent, be sure to watch for rattlesnakes as
-you walk about through the park, along the trails, and near the exhibits
-at Carnegie and University Hills. Avoid them if you see them, but do not
-harm them. As a general rule it is best to keep a good distance from any
-wildlife you see, not only to protect yourself and your children, but to
-avoid frightening or hurting the animal. It is best to observe wildlife
-at a safe distance with field glasses. While walking about the park, do
-not take chances by climbing on loose rock, or going into unauthorized
-areas, and do not let your children go beyond your control. Park your
-vehicle in authorized places and observe the normal rules of road safety
-and courtesy while you are in the park, and when entering and leaving
-it.
-
-
-                       Birding Along the Niobrara
-
-
-                        Taking the Annual Count
-
-One of the joys of visiting the national parks, author Freeman Tilden
-once said, is having an unexpected, provocative experience. You go to a
-park to see or do one thing, and you come across something else that
-strikes your fancy as well. Tilden called it serendipity. At Agate
-Fossil Beds National Monument, one such experience might be
-birdwatching. In this piece, Doris B. Gates writes of her annual bird
-surveys in this area.
-
-
-In western Nebraska the northern part of the Great Plains ends at the
-Pine Ridge, an escarpment circling from Wyoming across Nebraska's north
-edge and winding into South Dakota. A major grass of this mixed prairie
-is little bluestem, Nebraska's state grass, whose rusty-red hue in fall
-and winter gives much of the state its characteristic color.
-
-These plains are rarely broken by cultivation and only a few houses with
-their few trees break the landscape. The land's major change comes where
-the Niobrara River, here little more than a narrow creek, cuts a valley
-whose rock outcroppings provide homes for rock wrens, chipmunks, and
-bushy-tailed wood rats better known as pack or trade rats.
-
-    [Illustration: Swainson's hawk]
-
-Here, since 1967, near Agate Fossil Beds National Monument, my partner
-and I have taken part in the annual Breeding Bird Survey for the U.S.
-Fish and Wildlife Service. Part of one of our survey routes, Highway 29,
-crosses the monument's west end. We know the area--in June at
-least--quite intimately, when there is nothing quite so beautiful as a
-sunrise over these flower-dotted, green-grassed rolling hills along the
-Niobrara.
-
-We go many kilometers and make many bird counting stops, then we drop
-into the little valley where the Niobrara flows and suddenly we hear and
-see birds in such rapid succession that we have difficulty getting them
-all named in the three minutes allowed us under the survey rules.
-Actually, three stops are influenced by the river: on the south edge we
-have found a common nighthawk, a lark sparrow, and a Say's phoebe; on
-the north end the rock wren sings its un-wrenlike song. Near the bridge,
-where a narrow belt of shrubs and trees--mostly willows--hugs the river,
-we have logged the following: common flicker, a red-headed woodpecker,
-eastern and western kingbirds, western wood peewees, a blue jay,
-black-capped chickadees, house wrens, a brown thrasher, robins, yellow
-warblers, black-billed magpies, common grackles, black-headed grosbeaks,
-American goldfinches, and the non-native house sparrow and starling.
-Only once did we see or hear a black-billed cuckoo.
-
-                                                   _continues on page 85_
-
-    [Illustration: Red-winged blackbird chick]
-
-    [Illustration: Long-billed curlew chick]
-
-    [Illustration: Long-billed marsh wren]
-
-    [Illustration: Canada geese]
-
-    [Illustration: Long-billed curlew male]
-
-    [Illustration: House wren]
-
-    [Illustration: Nighthawk]
-
-    [Illustration: Marsh hawk chicks]
-
-    [Illustration: Killdeer]
-
-    [Illustration: Great horned owl]
-
-    [Illustration: Western meadowlark]
-
-    [Illustration: American bittern]
-
-    [Illustration: Pocket gopher]
-
-    [Illustration: Jackrabbit]
-
-    [Illustration: Hognose snake]
-
-    [Illustration: Fence lizard]
-
-    [Illustration: Coyote]
-
-    [Illustration: Pronghorn]
-
-If we stop and peer into a large culvert under the highway we may scare
-out a cloud of cliff swallows whose mud nests are stuck on culvert
-walls. Barn and rough-winged swallows are more rarely seen--usually near
-the Agate buildings.
-
-Near scattered farmhouses we may see logger-head shrikes; by one water
-tank we usually find a few killdeer. These and such birds as the
-long-billed curlew, upland sandpipers, and sharp-tailed grouse break the
-near monotony of such prairie birds as western meadowlarks (Nebraska's
-state bird), lark buntings, horned larks, and chestnut-collared
-longspurs. Lark buntings line the utility wires, taking off to sing
-their territorial songs, and descending with butterfly-like motions.
-
-Hawks are here--red-tails, Swainson's, ferruginous, marsh, and the
-little American kestrel--but in small numbers. We search long rows of
-fence posts for a burrowing owl and occasionally see one. Great-horned
-owls frequent tall cottonwood trees around the Agate ranch buildings.
-This is also the country of turkey vultures, golden eagles, and prairie
-falcons, but we have not been lucky enough to see them yet.
-
-Mammals are more elusive. Cattle pasture conspicuously on land formerly
-claimed by the buffalo (bison). We see pronghorns each year. A lone
-coyote is the only other relatively large mammal we have logged. Check a
-good mammal book and you will appreciate what lives here largely
-invisible to the untrained eye: shrews, moles, bats, cottontails and two
-kinds of jackrabbits, pocket gophers, prairie dogs, kangaroo rats,
-voles, several kinds of mice, two kinds of ground squirrel, muskrats,
-beaver, raccoons, minks, badgers, longtailed weasels, two kinds of
-skunks, occasional porcupines and bobcats, white-tailed deer, and mule
-deer. Consider yourself lucky if you see the swift fox, mountain lion,
-and the rare black-footed ferret.
-
-Life abounds here in other forms less noticeable to eyes trained on the
-Breeding Bird Survey: various species of amphibians, reptiles, fish, and
-the numerous insects associated with grasslands. We hear perhaps too
-much about rattlesnakes--western Nebraska has only the prairie rattler,
-whose numbers are now much reduced. Other snakes include western
-hognosed, blue racer, bullsnake, and the plains, wandering, and
-red-sided garter snakes.
-
-
-                  Collections of Agate Springs Fossils
-
-
-                         Museums You Can Visit
-
-Many museums throughout the world have displays of fossils from the
-Agate Fossil Beds. Very few of them actually collected their own
-material. Museum curators are dedicated "horse traders" and
-fossil-swapping is part of the business. When museums such as the
-Carnegie Museum of Pittsburgh or the American Museum of Natural History
-in New York make collections like the ones made at Agate earlier in this
-century, they usually have some trading stock left over after completing
-their study collections and exhibits. They then can trade an extra
-_Menoceras_ slab, for example, for a dinosaur skeleton from some faraway
-corner of the Earth.
-
-At several museums in this country you can see mounted skeletons of
-several animals found at Agate, along with _Menoceras_ slabs (sections
-of rock with the bones still imbedded) or models and dioramas of Agate
-specimens. To the right are listed, in order of proximity to the park,
-some of the museums and their specimens from Agate.
-
-The United States Museum of Natural History, Smithsonian Institution,
-has many fossils that depict the life of the most recent 65 million
-years and several murals by artist Jay H. Matternes showing the life of
-each of the epochs. The Miocene mural, reproduced on pages 20-21 of this
-handbook, is among these reconstructions. It depicts ancient life around
-what is today known as Agate Fossil Beds National Monument.
-
-  The Trailside Museum
-  Fort Robinson, Nebraska 69339.
-      _Menoceras_ slab, skeleton, and restoration
-      _Stenomylus_ skeleton on a slab, and a prepared limb
-      _Palaeocastor_ in a _Daemonelix_
-      _Palaeocastor_ in a plaster cast
-  Museum of Geology, South Dakota School of Mines and Technology
-  Rapid City, South Dakota 57701.
-      _Menoceras_ slab, beautifully prepared
-  The Geological Museum
-  University of Wyoming, Laramie, Wyoming 82070.
-      _Menoceras_, mounted skeleton
-      _Stenomylus_ slab containing most of a skeleton
-  University of Nebraska State Museum
-  101 Morrill Hall, 14th and U Streets, Lincoln, Nebraska 68508.
-      _Moropus_, mounted skeleton
-      _Palaeocastor_ skeleton in a _Daemonelix_; also, two other
-      _Daemonelix_
-      _Menoceras_ slab
-      _Dinohyus_ skeleton
-      _Stenomylus_, a group of skeletons
-  Field Museum of Natural History
-  Roosevelt Road at Lake Shore Drive, Chicago, Illinois 60605.
-      _Menoceras_ slab
-      _Moropus_ skeleton
-  The University of Michigan Exhibit Museum
-  1109 Geddes Rd., Ann Arbor, Michigan 48104.
-      _Menoceras_ slab and mounted skeleton
-      _Dinohyus_ eating dead Menoceras, a diorama
-      _Stenomylus_ skeleton and model
-  Carnegie Museum
-  4400 Forbes Ave., Pittsburgh, Pennsylvania 15213.
-      _Promerycochoerus_ slab
-      _Menoceras_ slab and mounted skeleton
-      _Moropus_, mounted skeleton
-      _Dinohyus_, mounted skeleton
-      _Stenomylus_, three skeletons mounted in a group
-  The American Museum of Natural History
-  Central Park West and 79th St., New York, New York 10024.
-      _Moropus_ skeleton
-      _Menoceras_ slab and skulls, one used in a sequence showing
-      collecting and preparation techniques
-      _Dinohyus_ skull
-      _Stenomylus_, nine skeletons and a reconstruction of the group
-      in life
-  Museum of Comparative Zoology
-  Harvard University, Oxford Street, Cambridge, Massachusetts 02138.
-      _Menoceras_ slab
-      _Dinohyus_ skeleton
-      _Stenomylus_ skeleton
-
-
-                     NPS Areas With Fossil Exhibits
-
-Several fossil sites in the United States are under the protection of
-the National Park Service. Besides Agate, the major ones are:
-
-
-                  Badlands National Park, South Dakota
-
-    [Illustration: Badlands]
-
-Prominent deposits from the Oligocene Epoch, predecessor to the Miocene,
-combine with a rugged, eroded landscape and abundant wildlife to make
-Badlands a park where the natural processes of the past combine with
-those of today. The National Park Service maintains a Fossil Exhibit
-Trail at Badlands and presents fossil cleaning demonstrations. Prominent
-fossils are those of ancient camels, giant pigs, sabertooth cats,
-_Protoceras_, and _Brontotheres_. Mailing address: P.O. Box 6, Interior,
-SD 57750.
-
-
-             Dinosaur National Monument, Colorado and Utah
-
-    [Illustration: Dinosaur]
-
-The late Jurassic muds and sands of the Morrison Formation have been a
-major source of dinosaur bones for more than a century. Steeply tilted
-strata near Vernal, Utah, were the source of tons of bones for the
-Carnegie Museum of Pittsburgh. This quarry site became the nucleus of
-Dinosaur National Monument. The bone-bearing stratum has been exposed by
-careful excavation, so that bones and partial skeletons of numerous
-dinosaurs are exposed in high relief. The entire quarry face is covered
-by a glass-walled structure that forms a large gallery. Mailing address:
-4545 E. Hwy. 40, Dinosaur, CO 81610.
-
-
-           Florissant Fossil Beds National Monument, Colorado
-
-This site has long been famous for its fossils of insects and plants
-preserved in fine-grained sediments. Specimens of _Brontothere_ indicate
-an Eocene age for the deposits. Mailing address: P.O. Box 185,
-Florissant, CO 80816.
-
-    [Illustration: Florissant]
-
-
-                Fossil Butte National Monument, Wyoming
-
-Within the strata of this rock remnant of an ancient lake is one of the
-most extensive concentrations of fossilized freshwater fish known to
-science. The site is about 18 kilometers (11 miles) west of Kemmerer,
-Wyoming. Mailing address: P.O. Box 592, Kemmerer, WY 83101.
-
-
-                Petrified Forest National Park, Arizona
-
-    [Illustration: Petrified Forest]
-
-Here in the Late Triassic Chinle Formation are widespread deposits of
-petrified logs. Some are nearly 2 meters in diameter and 60 meters long
-(6.5 by 197 feet). Preserved in bright colors of opal and other
-minerals, the most common trees are relatives of the living monkey
-puzzle or Hawaiian star pine. Paleontologists believe many of the logs
-floated to the area in Triassic rivers and became stranded. In the
-museum are displays of various fossil plant species and animal fossils
-from the same deposits. Mailing address: P.O. Box 2217, Petrified Forest
-National Park, AZ 86028.
-
-
-             John Day Fossil Beds National Monument, Oregon
-
-With a total of about 5,700 hectares (14,100 acres) in several
-noncontiguous units in north-central Oregon, this park provides an
-extensive record of Earth history dating back at least 37 million years.
-Plant and animal fossils are present in great variety. Mailing address:
-HCR 82, Box 126, Kimberly, OR 97848.
-
-
-             Hagerman Fossil Beds National Monument, Idaho
-
-Within the banks of the Snake River are preserved the last vestiges of
-late Pliocene life before the Ice Age and modern flora and fauna
-appeared. Mailing address: P.O. Box 570, Hagerman, ID 83332.
-
-
-                         Nearby National Parks
-
-While you're in the Agate Fossil Beds area, why not see some other sites
-in the National Park System? These parks offer a variety of experiences
-from frontier history presentations to caving.
-
-
-Badlands National Park is 97 kilometers (60 miles) southeast of Rapid
-City, South Dakota. This wonderland of bizarre, colorful spires and
-pinnacles, massive buttes, and deep gorges is open all year, though
-blizzards may temporarily block roads in the winter. Campfire programs
-and guided nature walks are presented. Backpackers will enjoy the park's
-wilderness area. The park has a herd of about 300 bison and some prairie
-dog towns. Mailing address: P.O. Box 6, Interior, SD 57750.
-
-    [Illustration: Devils Tower]
-
-
-Devils Tower National Monument is 47 kilometers (29 miles) northwest of
-Sundance, Wyoming. Known as Mato Tipila (Bear Lodge) to the Lakota, this
-towering landmark looms over the Belle Fourche River in the northeast
-corner of Wyoming. Here the Black Hills meet the plains grasslands, and
-you will likely see prairie dogs, as well as other mammals and a variety
-of birds. The park is open all year. Mailing address: P.O. Box 10,
-Devils Tower, WY 82714.
-
-    [Illustration: Fort Laramie]
-
-
-Fort Laramie National Historic Site is 5 kilometers (3 miles) southwest
-of Fort Laramie, Wyoming. The first fort on the site was built in 1834
-and soon became a lucrative center of the fur trade. The U.S. Army took
-over in 1849, using the fort to protect the Oregon Trail. The fort was
-abandoned by the Army in 1890. Several buildings are furnished as they
-would have been during the Army years of the 1870s and 1880s. The park
-is open all year. Mailing address: HC 72, Box 389, WY 82212.
-
-
-Jewel Cave National Monument is located on U.S. 16, 24 kilometers (15
-miles) west of Custer, South Dakota. The cave's name comes from the
-myriads of jewel-like calcite crystals that adorn its walls. Tours are
-conducted daily from mid-May through September. Tours, if any, the rest
-of the year are irregular. Mailing address: RR 1, Box 60 AA, Custer, SD
-57730.
-
-    [Illustration: Mount Rushmore]
-
-
-Mount Rushmore National Memorial is 40 kilometers (25 miles) southwest
-of Rapid City, South Dakota. The mountain sculpture of Washington,
-Jefferson, Theodore Roosevelt, and Lincoln is best viewed under morning
-light. From June 1 to Labor Day the faces are illuminated at night. The
-park is open all year. Mailing address: P.O. Box 268, Keystone, SD
-57751.
-
-    [Illustration: Scotts Bluff]
-
-
-Scotts Bluff National Monument is 8 kilometers (5 miles) southwest of
-Scottsbluff, Nebraska. This massive rock promontory rises 245 meters
-(800 feet) above the valley floor, and it served as a landmark to
-Indians, fur traders, and settlers traveling the Oregon Trail. It was
-named for a fur trapper, Hiram Scott, and has remained a symbol of the
-great overland migrations. The park is open all year. Mailing address:
-P.O. Box 27, Gering, NE 69341.
-
-
-Wind Cave National Park is 16 kilometers (10 miles) north of Hot Springs
-in southwest South Dakota. Two worlds meet here: the underground world
-of the cave and the life of the surface prairie. The cave gets its name
-from the wind blowing into or out of the cave. Mailing address: RR 1,
-Box 190, Hot Springs, SD 57747.
-
-
-                      Not So Nearby National Parks
-
-By expanding your travel perimeter even farther beyond Agate Fossil
-Beds, you can take in these other National Park System sites.
-
-
-Bighorn Canyon National Recreation Area straddles the Montana-Wyoming
-border, 67 kilometers (42 miles) from Hardin, Montana, and at Lovell,
-Wyoming. Access to boat ramps and campgrounds is from both ends of the
-long reservoir. Yellowtail Dam tours are given from Memorial Day to
-Labor Day. The visitor centers are open all year. Mailing address: P.O.
-Box 458, Fort Smith, Montana 59035.
-
-
-Little Bighorn Battlefield National Monument is 24 kilometers (15 miles)
-south of Hardin, Montana. Here on June 25, 1876, Lt. Col. George
-Armstrong Custer and five 7th Cavalry companies attacked and were
-surrounded and killed by Indians. Mailing address: P.O. Box 39, Crow
-Agency, MT 59022.
-
-    [Illustration: Rocky Mountain]
-
-
-Rocky Mountain National Park is northwest of Denver and about 3
-kilometers (2 miles) west of the community of Estes Park, Colorado. The
-park is one of America's most accessible mountainous areas. Trail Ridge,
-which crosses the Continental Divide, offers breathtaking views. Elk,
-mule deer, bear, cougar, and bighorn sheep roam mountain crags, meadows,
-and valleys. Mailing address: Estes Park, CO 80517.
-
-    [Illustration: Theodore Roosevelt]
-
-
-Theodore Roosevelt National Park is on Interstate 94 at Medora, North
-Dakota. A separate unit is 90 kilometers (56 miles) north on U.S. 85. In
-these magnificantly colored badlands along the Little Missouri River
-Roosevelt had an open-range ranch and developed his practical
-conservation philosophy. Both units have campgrounds. Mailing address:
-P.O. Box 7, Medora, ND 58645.
-
-
-                         Armchair Explorations
-
-
-                    Some Books You May Want to Read
-
-  Bartlett, Richard A., _Great Surveys of the American West_, University
-  of Oklahoma Press, 1962.
-
-  Camp, Charles L., _Earth Song: A Prologue to History_, American West
-  Publishing Co., 1970.
-
-  Colbert, Edwin H., _Evolution of the Vertebrates_, John Wiley and
-  Sons, Inc., 1969.
-
-  Cook, Harold J., _Tales of the 04 Ranch_, University of Nebraska
-  Press, 1968.
-
-  Cook, James H., _Fifty Years on the Old Frontier_, University of
-  Oklahoma Press, 1980.
-
-  Gould, Stephen Jay, _Ever Since Darwin: Reflections in Natural
-  History_, W. W. Norton and Co., 1977.
-
-  Howard, Robert West, _The Dawn-seekers_, Harcourt Brace Jovanovich,
-  1975.
-
-  Johnson, Kirk R. and Richard K. Stucky, _Prehistoric Journey: A
-  History of Life on Earth_, Roberts Rinehart, 1995.
-
-  Lanham, Url, _The Bone Hunters_, Columbia University Press, 1973.
-
-  Laporte, L�o F., _Evolution and the Fossil Record_, W. H. Freeman Co.,
-  1978.
-
-  Larson, Robert W., _Red Cloud: Warrior-Statesman of the Lakota Sioux_,
-  University of Oklahoma Press, 1997.
-
-  Mason, Stephen F., _A History of the Sciences_, Collier Books, 1970.
-
-  Meade, Dorothy Cook, _Heart Bags & Handshakes: The Story of the Cook
-  Collection_, National Woodlands Pub. Co., 1994.
-
-  Osborn, Henry F., _Cope: Master Naturalist_, Princeton University
-  Press, 1931.
-
-  Paul, R. Eli, _Autobiography of Red Cloud: War Leader of the Oglalas_,
-  Montana Historical Society Press, 1997.
-
-  Plate, Robert, _The Dinosaur Hunters: Othniel C. Marsh and Edward D.
-  Cope_, McKay Co., 1964.
-
-  Raup, David M. and Steven M. Stanley, _Principles of Paleontology_, W.
-  H. Freeman Co., 1978.
-
-  Romer, Alfred Sherwood, _Vertebrate Paleontology_, University of
-  Chicago Press, 1966.
-
-  Schuchert, Charles and Clara Mae LeVene, _O.C. Marsh: Pioneer in
-  Paleontology_, Yale University Press, 1940.
-
-
-                                 Index
-
-  _Numbers in italics refer to photographs, illustrations, charts, or
-                                 maps._
-
-
-                                   A
-  _Aepinacodon_ _54-55_, 60
-  Agate Fossil Beds National Monument 11, 14, 50;
-      animals at, _20-22_, 24-34, _84_;
-      birding at, 81, _82-83_, 85;
-      established, 17, 78;
-      geology of 23, 47-52;
-      museum specimen of, 38, _86-87_;
-      topography of, 7;
-      visitor information 77-80
-  Agate Springs Ranch 7, 10, 17;
-      excavations at, 38, _39_; fossils from, _40-41_, 86-87
-  Alligator _54-55_, 60
-  American Museum of Natural History 14, 38, 52, 87
-  _Aplodontia_ 32
-
-
-                                      B
-  Badlands National Park, South Dakota _88_, 90
-  Barbour, Erwin H. 11, 14, 38
-  Big Badlands, South Dakota 49, 52
-  Bighorn Canyon National Recreation Area, Montana-Wyoming 92
-  Bittern, American _83_
-  Blackbird, red-winged _82_
-  Bone Cabin, Wyoming 48
-  Breeding Bird Survey, U.S. Fish and Wildlife 81, _82-83_, 85
-  Buteos (buzzard hawks) 28
-
-
-                                      C
-  Cambrian period _46_
-  Camels. _See_ _Oxydactylus_, _Stenomylus_
-  Camping 78
-  Carboniferous period _46_
-  Carnegie Hill _12-13_, 14, 37, 77
-  Carnegie Museum 14, 38, 39, _40-41_, 69, 87, 88
-  Carnivores, small 32-34
-  Cenozoic Era _46_, 47, 49, 52
-  Chalicotheres. _See_ _Moropus_
-  Cheyenne River 52
-  Cleveland, Utah 48
-  Colorado Plateau 49
-  Como Bluff, Wyoming 48
-  Cook, Eleanor Barbour 14
-  Cook, Harold 10, 14, 17, 52
-  Cook, James H. _6_, 8, 10-11, 14, 77;
-      buys Agate Springs Ranch, 7, 10;
-      discovers fossils, 11, 24, 38
-  Cook, Kate Graham 10-11, 14
-  Cook, Margaret Crozier 17
-  Cook Museum of Natural History 17
-  Cope, Edward Drinker _9_, 11, 14
-  Coyote _84_
-  Cretaceous period _46_
-  Curlew, long-billed _82_
-  Cuvier, Georges 42, _43_, 45
-  Custer Battlefield National Monument. _See_ _Little Bighorn
-          Battlefield National Monument_
-
-
-                                      D
-  _Daemonelix_ 33, _69_, 70, 86
-  _Daphoenodon_ _20-21_, 22, 32, 38
-  Darwin, Charles 43, _44_, 45
-  Devil's Corkscrew _76_
-  Devils Tower National Monument, Wyoming _90_
-  Devonian period _46_
-  _Diceratherium_ 24. _See also_ _Menoceras_
-  _Dinohyus_ _20-21_, 22, 30, 87
-  Dinosaur National Monument, Colorado and Utah 42, 48, _88_
-  Drought 35, 36, 50-51
-
-
-                                      E
-  Ecology 53, 61-73
-  _Entelodon_ 30
-  Entelodont 30
-  Eocene epoch 25, 27, 29, 31, _46_, 49, 53, 63, 88
-  _Equus_ 63
-  Excavations 38, _39_
-
-
-                                      F
-  Field Museum of Natural History 87
-  Flora 7, 10, 53, _54-59_, 60, 71-73
-  Florissant Fossil Beds National Monument, Colorado 53, 88, _89_
-  Folsom, New Mexico 14;
-      spearpoint, 17
-  Fort Laramie National Historic Site, Wyoming _90_
-  Fort Robinson State Park, Nebraska 50, 77
-  Fossil Butte National Monument, Wyoming 89
-  Fossils _38-41_, 47, 86-89
-
-
-                                      G
-  Geological Museum, University of Wyoming 86
-  Geology 35, _46_, 47-52
-  Geese, Canada _82_
-  Gerenuk 29
-  Gering Formation 50
-  Gopher, pocket _84_
-  Graham, Elisha B. 10
-  Graham, Mary 10-11
-  Grasslands 26, 35, 51, 61, 71-72
-  _Gregorymys_ 33
-  Guan 28
-
-
-                                      H
-  Hagerman Fossil Beds National Monument, Idaho 89
-  Harrison Formation 23, 50, 63
-  Hawk _56-57_, 60;
-      marsh _83_;
-      nighthawk _83_;
-      Swainson's _81_
-  Horses 62-63, _66-67_. _See also_ _Merychippus_, _Miohippus_,
-          _Parahippus_, _Protohippus_
-  Hutton, James 45
-
-
-                                      J
-  Jackrabbit _84_
-  Jefferson, Thomas 42
-  Jewel Cave National Monument, South Dakota 91
-  John Day Fossil Beds National Monument, Oregon 89
-  Jurassic period _46_
-
-
-                                      K
-  Killdeer _83_
-
-
-                                      L
-  Laboratory _40-41_
-  Lamarck, Jean-Baptiste de _43_
-  Laramide Revolution 49
-  Linnaeus, Carolus _43_
-  Little Bighorn Battlefield National Monument 92
-  Lucretius (Titus Lucretius Carus) 42
-  Lyell, Charles 42, 43, _45_
-
-
-                                      M
-  Map _78_, _79_
-  Marsh, Othniel C. _8_, _9_, 11
-  Marsland Formation 50, 51
-  Matthew, W. D. 52
-  McJunkin, George 14
-  Meadowlark, western _83_
-  _Meniscomys_ 32-33
-  _Menoceras_ 14, _20-21_, _22_, _24_, 25, 36, 38, 51, 86, 87
-  _Merychippus_ 52, _58-59_, 60, 62-63
-  _Merychyus_ _20-21_, 22
-  Mesozoic era _46_, 47-49
-  Miocene epoch _46_, 49-52, 71-73;
-      animals of 20-37, 62, 63, _64-69_, 70;
-      birds of 28
-  _Miohippus_ 25-26, 27, 64, _66-67_
-  Mississippi Embayment 35, 49
-  Monroe Creek Formation 50
-  Morrison, Colorado 48
-  _Moropus_ _20-21_, 22, _29-30_, 86-87
-  Mount Rushmore National Memorial, South Dakota _91_
-  Museum of Comparative Zoology, Harvard University 87
-  Museum of Geology, South Dakota School of Mines and Technology 86
-  Museums, fossils at _86-87_. _See also_ _American Museum of
-          Natural History_, _Carnegie Museum_
-
-
-                                      N
-  _Nanotragulus_ 27-28
-  National Park Service 17, 88-92
-  Nighthawk _83_
-  _Nimravus_ 32
-  Niobrara River 7, _16_, 23-24, 36, 37, 50, _54-55_, _60_
-  North Platte River 52
-  _Nothocyon_ 32, 33
-
-
-                                      O
-  Oglala Sioux Indians 7, 11. _See also_ _Red Cloud_
-  _Oligobunis_ 32
-  Oligocene epoch 25, 31, _46_, 49, 50, 52, 53, 70, 88;
-      animals of 61, 63
-  Opossum _54-55_, 60
-  Ordovician period _46_
-  _Oreodon_ 25, _54-55_, 60, 63
-  Osborn, Henry F. 14, 38
-  Owl, great horned _83_
-  _Oxydactylus_ _20-21_, 22, 28, _56-57_, 60
-
-
-                                      P
-  _Palaeocastor_ 14, _20-21_, 22, _33_, 64, _68-69_, 70-71, 77, 86
-  _Palaeolagus_ 34
-  Paleocene epoch _46_, 53
-  Paleozoic era _46_, 47-48
-  _Parahippus_ _20-21_, 22, _27_, _56-57_, 60, 62, 67
-  Permian period _46_
-  Peterson, O. A. 14, 38, 39
-  Petrified Forest National Park, Arizona _89_
-  Pigs 30-31
-  Pine Ridge, South Dakota 52
-  Pleistocene epoch 28-29, _46_, _64_, 67
-  Pliocene epoch 24-25, 27, _46_, 52, 63
-  _Portheus_ 48
-  Precambrian era _46_
-  _Promerycochoerus_ _20-21_, 22, 25, 87
-  Pronghorn (artiodactyls) 63, _84_. _See also_ _Syndyoceras_
-  _Protoceras_ 31
-  _Protohippus_ 62, 63
-  _Pseudaelurus_ 32, _58-59_, 60
-
-
-                                      Q
-  Quaternary period _46_
-
-
-                                      R
-  Red Cloud 9, 11
-  Rhinoceros 24-25, 50, 51, 63
-  Rocky Mountain National Park, Colorado 92
-  Rocky Mountain Revolution 51, 52
-  Runningwater Formation 51
-  Rodents 32-34
-
-
-                                      S
-  Sandpiper, upland _14_
-  Scotts Bluff National Monument, Nebraska 49, _91_
-  Sheep Creek Formation 52
-  Silurian period _46_
-  Smiley Canyon, Nebraska 50
-  Snake, hognose _84_
-  _Stenomylus_ 14, _20-21_, 22, _29_, 37, _39_, 50, _64-65_, 86, 87;
-      _hitchcocki_, 51
-  Sundance Formation 48
-  _Syndyoceras_ _20-21_, 22, _31_
-  _Synthetoceras_ 31-32
-
-
-                                      T
-  Teeth, high-crowned 62-63
-  _Temnocyon_ 32
-  Tertiary period _46_, 53
-  Theodore Roosevelt National Park, North Dakota 92
-  Thompson, Albert 14, 38
-  Toadstool Park, Nebraska 49
-  Tortoise 33-34
-  Trailside Museum, Nebraska 86
-  Triassic period _46_
-
-
-                                      U
-  Uniformitarianism 42, 43, 45
-  University Hill 7, _12-13_, 35;
-      digging at, 14;
-      formation of 37;
-      tourist facilities at, 77
-  University of Nebraska State Museum 86
-
-
-                                      V
-  Visitor information 77-80, 86-92
-  Von Linne, Karl _43_
-
-
-                                      W
-  Wallace, Alfred _45_
-  White River 52;
-      Badlands 31;
-      Beds 49
-  Wildflowers 7, 10
-  Wind Cave National Park, South Dakota 91
-  Wren, house _82_;
-      long-billed marsh _82_
-
-
-  *GPO: 1999--454-765/00504
-  Reprint 1999
-
-
-
-
-                         National Park Service
-
-
-The National Park Service expresses its appreciation to all those
-persons who made the preparation and production of this handbook
-possible. The Service also gratefully acknowledges the financial support
-given this handbook project by the Oregon Trail Museum Association, a
-nonprofit group that assists interpretive efforts at Agate Fossil Beds
-National Monument.
-
-
-                                 Texts
-
-James R. and Laurie J. Macdonald, authors of "A Landscape Rich With
-Life" in Part 2, are paleontologists who live in Sunnyvale, California,
-and teach nearby.
-
-Doris B. Gates, writer of "Birding Along the Niobrara" in Part 3, is a
-retired biology professor who lives in Chadron, Nebraska.
-
-
-                                  Maps
-
-R.R. Donnelly & Sons Co. 79.
-
-
-                             Illustrations
-
-
-  Jay H. Matternes, who painted the wildlife panoramas and animal
-          features on the cover and in Part 2, is a paleontological
-          reconstruction artist who lives in Fairfax, Virginia. In Part
-          2 his illustrations appear on pages 20-21, 24, 25, 27-33,
-          54-59, 64-69.
-  American Museum of Natural History 9 Cope.
-  Greg Beaumont 14, 81-84.
-  Carnegie Museum 38-41.
-  Library of Congress 43-45.
-  James O. Milmoe 12-13, 15, 16, 76.
-  Peabody Museum of Natural History, Yale University 8.
-  All other illustrations are from the files of Agate Fossil Beds
-          National Monument and the National Park Service.
-
-
-
-
-                    U.S. Department of the Interior
-
-
-The mission of the Department of the Interior is to protect and provide
-access to our Nation's natural and cultural heritage and honor our trust
-responsibilities to tribes. The National Park Service preserves
-unimpaired the natural and cultural resources and values of the National
-Park System for the enjoyment, education, and inspiration of this and
-future generations. The National Park Service cooperates with partners
-to extend the benefits of natural and cultural resource conservation and
-outdoor recreation throughout this country and the world.
-
-
-
-
-                           Agate Fossil Beds
-
-
-     _Through the remains of animals long extinct, excavated here at
-    this site, Agate Fossil Beds National Monument tells the story of
-    the Miocene Epoch--the Age of Mammals--that occurred 5 to 23 million
-    years ago. The scene on the front cover is from a mural by artist
-    Jay H. Matternes that depicts animals of the Early Miocene._
-
-    [Illustration: _In addition to fossils, the park has an extensive
-    collection of Plains Indian art and artifacts, such as this shirt
-    that belonged to Red Cloud._]
-
-
-
-
-                          Transcriber's Notes
-
-
---Retained publication information from the printed edition: this eBook
-  is public-domain in the country of publication.
-
---Relocated all image captions to be immediately under the corresponding
-  images, removing redundant references like "preceding page".
-
---Silently corrected a few palpable typos.
-
---In the text versions only, text in italics is delimited by
-  _underscores_.
-
---Conjecturally restored one subsection of the index entry for "Agate
-  Springs Ranch"
-
-
-
-
-
-
-
-End of the Project Gutenberg EBook of Agate Fossil Beds National Monument,
-Nebraska, by United States National Park Service
-
-*** END OF THIS PROJECT GUTENBERG EBOOK AGATE FOSSIL BEDS NATIONAL MONUMENT ***
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-<pre>
-
-The Project Gutenberg EBook of Agate Fossil Beds National Monument,
-Nebraska, by United States National Park Service
-
-This eBook is for the use of anyone anywhere in the United States and most
-other parts of the world at no cost and with almost no restrictions
-whatsoever.  You may copy it, give it away or re-use it under the terms of
-the Project Gutenberg License included with this eBook or online at
-www.gutenberg.org.  If you are not located in the United States, you'll have
-to check the laws of the country where you are located before using this ebook.
-
-Title: Agate Fossil Beds National Monument, Nebraska
-
-Author: United States National Park Service
-
-Release Date: January 4, 2018 [EBook #56303]
-
-Language: English
-
-Character set encoding: UTF-8
-
-*** START OF THIS PROJECT GUTENBERG EBOOK AGATE FOSSIL BEDS NATIONAL MONUMENT ***
-
-
-
-
-Produced by Stephen Hutcheson and the Online Distributed
-Proofreading Team at http://www.pgdp.net
-
-
-
-
-
-
-</pre>
-
-<div id="cover" class="img">
-<img id="coverpage" src="images/cover.jpg" alt="Agate Fossil Beds National Monument, Nebraska" width="500" height="707" />
-</div>
-<div class="box">
-<h1>Agate Fossil Beds</h1>
-<p class="center"><span class="ss">Agate Fossil Beds National Monument
-<br />Nebraska</span></p>
-<p class="center"><span class="ss">Produced by the
-<br />Division of Publications
-<br />Harpers Ferry Center
-<br />National Park Service</span></p>
-<p class="center"><span class="ss">U.S. Department of the Interior
-<br />Washington, D.C.</span></p>
-</div>
-<h4 id="ccc1">The National Park Handbook Series</h4>
-<p>National Park Handbooks, compact introductions
-to the great natural and historic places administered
-by the National Park Service, are designed
-to promote understanding and enjoyment of the
-parks. Each is intended to be informative reading
-and a useful guide before, during, and after a park
-visit. More than 100 titles are in print. This is
-Handbook 107. You may purchase the handbooks
-through the mail by writing to Superintendent of
-Documents, U.S. Government Printing Office,
-Washington DC 20402.</p>
-<h4 id="ccc2">About This Book</h4>
-<p>What was life like in North America 20 million
-years ago? Agate Fossil Beds provides a glimpse
-of that time, long before the arrival of man, when
-now-extinct creatures roamed the land which we
-know today as Nebraska. <a href="#c1">Part 1</a> of this handbook
-introduces you to the park; <a href="#c3">Part 2</a> brings life to
-the fossil specimens and examines the area&rsquo;s geological
-and ecological evidence; and <a href="#c8">Part 3</a> presents
-concise guide and reference information.</p>
-<h4 id="ccc3">Library of Congress Cataloging in Publication Data</h4>
-<dl class="undent"><dt>United States. National Park Service.</dt>
-<dt>Agate Fossil Beds National Monument, Nebraska.</dt>
-<dt>(National park handbook; 107) Bibliography: p.</dt>
-<dt>Includes index.</dt>
-<dt>Supt. of Docs. no. I29.9/5:107</dt>
-<dt>1. Vertebrates, Fossil.</dt>
-<dt>2. Paleontology&mdash;Miocene.</dt>
-<dt>3. Paleontology&mdash;Nebraska&mdash;Agate Fossil Beds National Monument.</dt>
-<dt>4. Natural history&mdash;Nebraska&mdash;Agate Fossil Beds National Monument.</dt>
-<dt>5. Agate Fossil Beds National Monument, Neb.</dt>
-<dt>I. Title.</dt>
-<dt>II. Series: United States. National Park Service. Handbook&mdash;National Park Service; 107.</dt>
-<dt>QE841.U59<span class="hst"> 1980</span><span class="hst"> 566&prime;.09782&prime;99</span><span class="hst"> 80-607119</span></dt></dl>
-<h3><span class="center">Contents</span></h3>
-<dl class="toc">
-<dt><a href="#c1">Part 1 Welcome to Agate Fossil Beds</a> 4</dt>
-<dd><a href="#c2">Worlds of Past and Present</a> 7</dd>
-<dt><a href="#c3">Part 2 A Landscape Rich With Life</a> 18</dt>
-<dd class="jl"><i>Text: James R. and Laurie J. Macdonald</i></dd>
-<dd class="jl"><i>Illustrations: Jay H. Matternes</i></dd>
-<dd><a href="#c4">A Visit to the Past</a> 23</dd>
-<dd><a href="#c5">The Mark of Death Upon the Land</a> 35</dd>
-<dd><a href="#c6">The Geologic History of Agate</a> 47</dd>
-<dd><a href="#c7">Ecology: Change and Adaptation</a> 53</dd>
-<dt><a href="#c8">Part 3 Guide and Adviser</a> 74</dt>
-<dd><a href="#c9">Contents for this section</a> 77</dd>
-</dl>
-<div class="pb" id="Page_4">4</div>
-<h2 id="c1"><span class="small">1 <span class="hst">Welcome to Agate Fossil Beds</span></span></h2>
-<div class="pb" id="Page_6">6</div>
-<div class="img" id="fig1">
-<img src="images/i02.jpg" alt="" width="562" height="800" />
-<p class="pcap">James H. Cook examines a
-fossil fragment at the quarries
-near Agate Springs
-Ranch about 1918.</p>
-</div>
-<div class="pb" id="Page_7">7</div>
-<div class="img" id="fig2">
-<img src="images/i02a.jpg" alt="" width="388" height="601" />
-<p class="pcap">Besides
-fossils, Cook also collected
-Indian artifacts and kept
-many of them on the walls
-of his study in the ranch
-house.</p>
-</div>
-<h3 id="c2">Worlds of Past and Present</h3>
-<p>Imagine that you are a healthy young man, raised
-conservatively in Michigan several years after the
-end of the Civil War. You are a skilled all-around
-hunter and trapper. The railroad has just spanned
-the continent, and stories of the West, its dangers,
-its people, and its opportunities come to you frequently.
-You and a friend decide you must see this
-land for yourself, and you save your money carefully
-against the day when you will be ready to go
-west. Around 1869, at age 12, that day comes.</p>
-<p>At Fort Leavenworth, Kansas, you meet several
-cattlemen who tell you and your friend where to get
-work as cattle herders. Before many years have
-passed you have been a cowpuncher in Texas, you
-have fought Comanches, and you have bossed a
-ranch crew for a wealthy Englishman. You go on to
-fight the famous Apache Chieftain Geronimo as a
-scout with the U.S. Cavalry, and you befriend a famous
-Sioux chief, Red Cloud. You marry, buy a
-ranch in western Nebraska, and raise a family. And
-you become something of a legend in your own time,
-your ranch known for its hospitality to Indian, scientist,
-traveler&mdash;to one and all, rich or poor.</p>
-<p>A movie script? Not at all&mdash;these are the essentials
-of the life of James H. Cook. Known as &ldquo;Captain,&rdquo;
-James Cook became the owner, in 1887, of the Agate
-Springs Ranch, founded earlier by his father-in-law.
-Under Cook&rsquo;s watchful eye, the ranch prospered and
-became a second home both for the Oglala Sioux
-and for paleontologists bent on excavating the fossilized
-remains of the life of 20 million years ago,
-found here along the Niobrara River in western Nebraska.</p>
-<p>This land, now encompassing Agate Fossil Beds
-National Monument, is punctuated with low bluffs
-ascending westward toward the Rockies. It is a land
-of sharp contrasts, of cool, inviting riverbanks and
-parched ridges, the most famous of which are the
-fossil-bearing Carnegie and University Hills. The
-surrounding grassy plains are a tapestry of wild
-grasses&mdash;prairie sandreed, blue grama, little bluestem,
-and needle-and-thread. The wildflowers lupine,
-spiderwort, western wallflower, sunflower, and
-penstemon add touches of blue, purple, orange, yellow,
-and red to the tapestry. In summer the dark
-green spears of the small soapweed, a yucca, dot the
-brown grasses of the hillsides. And just as they did
-more than 20 million years ago, cottonwoods and
-willows provide shade and shelter for birds and other
-animals along the river.</p>
-<div class="pb" id="Page_8">8</div>
-<div class="img" id="fig3">
-<img src="images/i03.jpg" alt="" width="1000" height="652" />
-<p class="pcap">Professor Othniel C. Marsh, back row center, of Yale University
-and his students look as if they are equipped for a
-frontier hunting expedition. But instead of looking for live
-animals in the West, they were hunting for fossilized remains
-of ancient beasts. Marsh and his crews made many such
-trips, and it was on one early trip that Cook and Marsh met, in Sioux country.</p>
-</div>
-<div class="pb" id="Page_9">9</div>
-<div class="img" id="fig4">
-<img src="images/i03a.jpg" alt="" width="538" height="800" />
-<p class="pcap">Professor Marsh and the great Sioux chief Red Cloud greet
-each other in New Haven in 1880.</p>
-</div>
-<div class="img" id="fig5">
-<img src="images/i03d.jpg" alt="" width="389" height="600" />
-<p class="pcap">Professor Edward Drinker Cope competed with Marsh
-for the best fossils. He once made the mistake of reconstructing
-a skeleton hind end foremost; Marsh never let him forget it.</p>
-</div>
-<div class="pb" id="Page_10">10</div>
-<p>Looking out over the rippling grasses, you grasp
-the fact that Nebraska is larger than all of New England
-and feel the awesome spaciousness of the Great
-Plains. The word &ldquo;distance&rdquo; has a different meaning
-here than it does in the East. When James Cook
-came to the upper Niobrara River, the closest town
-was Cheyenne, Wyoming&mdash;more than 160 kilometers
-(100 miles) to the southwest.</p>
-<p>It was there, in Cheyenne, that Cook met Dr.
-Elisha B. Graham in 1879, the year Graham selected
-this land for a cattle ranch as an investment and as
-a summer retreat for his family. Graham named the
-place the 04 Ranch, apparently because it is near the
-104th meridian. Cook visited the ranch often in the
-early 1880s and courted Elisha and Mary Graham&rsquo;s
-daughter Kate. They were married in 1886 and lived
-near Socorro, New Mexico, for a year before returning
-to Nebraska with their newborn child, Harold,
-and buying the ranch from Dr. Graham, who
-moved to California.</p>
-<p>Cook began at once to make improvements to the
-ranch. He planted trees by the hundreds and carried
-water to them faithfully to get them started. As settlers
-failed to &ldquo;prove up&rdquo; their land claims over the
-years, he added new lands to the ranch and changed
-the name to Agate Springs Ranch in recognition of
-the native moss agates and the many springs in the
-valley. He and Kate raised fine race horses as well
-as cattle.</p>
-<p>The period in which the Cooks took over the ranch
-was one of transition from the frontier days of migrations
-and Indian wars to more settled, orderly
-lives. Ranching and farming became the dominant
-mode of life in the eastern approaches to the Rockies.
-Even oil exploration played a part in the development
-of the land. The transition was a difficult
-one for many, Indian and settler alike.</p>
-<p>In some ways Kate Cook represented both the old
-and the new in Nebraska. She was a fine horsewoman;
-one day she rode a bucking horse through
-<span class="pb" id="Page_11">11</span>
-the streets of Cheyenne sidesaddle to win a bet for
-her husband. She was refined, too, having taught
-herself French so she could read French literature.
-Her mother, Mary Graham, became the first postmistress
-for the small community around Agate.</p>
-<p>And James Cook was more than an adventuresome
-frontiersman. He was actively interested in
-community and national affairs and in current scientific
-questions. He became a patient, knowledgeable
-mediator between the Indians and the settlers,
-and he was looked upon by the Oglala Sioux as a
-friend and host, and sometimes employer.</p>
-<p>The Cooks became involved in a great scientific
-enterprise quite accidentally around 1885, the year
-before their marriage. On a ride up the conical
-buttes not far from the ranch house, a glitter under
-a rock shelf caught Cook&rsquo;s eye. They found fragments
-of bones scattered on the ground. At first
-they assumed the bones were those of an Indian.
-But Cook found instead &ldquo;a beautifully petrified
-piece of the shaft of some creature&rsquo;s leg bone.&rdquo; They
-carried it back to the house but didn&rsquo;t report the
-find until after they bought the ranch. Erwin Barbour
-of the University of Nebraska was the first to
-respond to their reports and in 1892 became the
-first professional geologist to visit the area and do
-some prospecting.</p>
-<p>The Cooks&rsquo; discovery thrust them and their ranch
-into a subtle battle in the American West, a continuing
-struggle to find the best fossils with which
-to reconstruct the ancient past. For centuries it had
-been thought that life on our planet was only a few
-thousand years old, but by the late 19th century science
-had evolved beyond that point of view. Now
-paleontologists and their excavation teams were
-scouring the West in search of fossils that might
-provide clues to the beginnings of life.</p>
-<p>The two most noted antagonists in this feverish
-search were Professors Edward D. Cope of Philadelphia
-and Othniel C. Marsh of Yale University. Cook
-knew them both, but the discoveries at Agate would
-wait for the next generation of scientists.</p>
-<div class="pb" id="Page_12">12</div>
-<div class="img" id="fig6">
-<img src="images/i04.jpg" alt="" width="1000" height="721" />
-<p class="pcap">University Hill, left, and Carnegie Hill dominate
-the Niobrara River Valley. The hills received their
-names from the paleontological teams that worked them
-from the University of Nebraska and the Carnegie Museum.</p>
-</div>
-<div class="pb" id="Page_14">14</div>
-<p>Cook had first met Marsh in 1874. Marsh had
-just arrived in Oglala Sioux country to hunt fossils,
-but the Sioux Chief Red Cloud was suspicious. Red
-Cloud was convinced Marsh and his men were just
-another party of gold seekers. Cook, an able linguist,
-was then trailing cattle from Texas to the northern
-railroads and reservations. He persuaded Red Cloud
-that Marsh wanted only &ldquo;stone bones&rdquo; and averted
-a potentially disastrous clash. This incident led to
-a lifelong friendship between Cook and Red Cloud.
-And for Marsh this proved to be the last of many
-expeditions as he relied on others to send him specimens
-from likely fossil sites throughout the West.</p>
-<div class="img" id="fig7">
-<img src="images/i05.jpg" alt="" width="391" height="600" />
-<p class="pcap">An upland sandpiper, one of many birds that can be seen at
-Agate Fossil Beds, perches on a fence post.</p>
-</div>
-<p>Professor Cope and his crews often worked the
-same localities as Marsh. Like Marsh, Cope tried to
-get the best specimens, and each occasionally outbid
-the other for them, leaving bewildered farmers
-and ranchers to puzzle over these men&rsquo;s obsession
-with the past. Conflict also arose over the naming
-of animals previously unknown to science.</p>
-<p>The hills of Agate Springs Ranch proved to be a
-rich archive of ancient life. Dr. Barbour and his students
-confined their efforts to what soon became
-known as University Hill. Thus began a quiet rivalry
-with Olaf Peterson and his crew from the Carnegie
-Museum in Pittsburgh, Pennsylvania, who worked
-what became known as Carnegie Hill. The most
-numerous fossils these teams found at Agate are the
-remains of the pony-sized rhinoceros <i>Menoceras</i>, but
-the site also is known for fossils of the gazelle-like
-camel <i>Stenomylus</i>, the early small horse <i>Miohippus</i>,
-and the corkscrew burrows of an ancient beaver,
-<i>Palaeocastor</i>.</p>
-<p>Other distinguished scientists visited Agate over
-several decades. Among them were Henry Fairfield
-Osborn and Albert Thompson of the American
-Museum of Natural History in New York. The collections
-these men made at Agate are still being
-studied and exhibited.</p>
-<p>James and Kate Cook&rsquo;s older son Harold caught
-the fever, too. He became a trained geologist and
-in 1910 married another geologist, Eleanor Barbour,
-daughter of the distinguished Nebraska geologist.
-The new generation of Cooks continued the tradition
-of hospitality and scientific interest, encouraging
-further excavations of the fossil treasures of
-Agate. Perhaps Harold Cook&rsquo;s greatest moment of
-scientific glory came in 1926, when he and other
-scientists participated in the finds at Folsom, New
-Mexico, which proved to be a turning point in the
-study of the human prehistory of North America.
-George McJunkin, a black cowboy, had spotted the
-ribs of an animal protruding from the banks of an
-arroyo. The Folsom spearpoint and the bones of an
-extinct form of bison found there indicated that
-humans had lived on this continent for more than
-10,000 years, a startling revelation at that time
-though today scientists put the figure at more than
-40,000 years.</p>
-<div class="pb" id="Page_15">15</div>
-<div class="img" id="fig8">
-<img src="images/i05a.jpg" alt="" width="568" height="800" />
-<p class="pcap">Next to the fence
-stands a windmill, which once provided water for excavation teams.</p>
-</div>
-<div class="pb" id="Page_16">16</div>
-<div class="img" id="fig9">
-<img src="images/i06.jpg" alt="" width="679" height="1000" />
-<p class="pcap">The narrow Niobrara River
-winds through the surrounding
-tableland, carving
-out bluffs and exposing
-occasional fossils.</p>
-</div>
-<div class="pb" id="Page_17">17</div>
-<p>In time the Cooks&rsquo; house became a repository for
-a substantial number of Indian artifacts and natural
-history specimens. On summer weekends and holidays
-tourists ventured out to the ranch to see the
-Cook Museum of Natural History. James Cook personally
-guided many through the collection, but
-usually the whole family participated, leading the
-curious through three rooms and a small hallway.</p>
-<p>Harold Cook wanted Agate Springs Ranch to provide
-an enduring memorial to the ancient past.
-Soon after his death in 1962 his second wife, Margaret
-Crozier Cook, and friends began a campaign
-to add the fossil beds to the National Park System.
-Their efforts succeeded in 1965, when Congress
-authorized the establishment of Agate Fossil Beds
-National Monument.</p>
-<p>Today you can walk about Carnegie and University
-Hills where the great digs took place. You can
-see a few exposed fossil specimens, and you can try
-to recreate in your mind the life and landscape of
-this part of Nebraska 20 million years ago. To help
-you do that, we have asked paleontologists James R.
-and Laurie J. Macdonald, in <a href="#c3">Part 2</a> of this handbook,
-to take you on a journey to the past and then
-examine the evidence.</p>
-<p class="tb">Welcome to the worlds of past and present at Agate
-Fossil Beds National Monument.</p>
-<div class="pb" id="Page_18">18</div>
-<h2 id="c3"><span class="small">2 <span class="hst">A Landscape Rich With Life</span></span></h2>
-<p class="center"><i>Text: James R. and Laurie J. Macdonald</i>
-<br /><i>Illustrations: Jay H. Matternes</i></p>
-<div class="pb" id="Page_20">20</div>
-<div class="img" id="fig10">
-<img src="images/i07.jpg" alt="" width="1000" height="722" />
-<p class="pcap">This mural depicts life in the
-Agate Fossil Beds area in the
-early Miocene Epoch, about
-20 million years ago when the
-story on the following pages
-takes place. The painting is a
-composite of life at that time;
-if you had been there then,
-you would not have been able
-to see all of these forms of life
-together at any given moment!
-The original mural hangs in
-the fossil halls at the Smithsonian
-Institution&rsquo;s National
-Museum of Natural History in
-Washington, D.C.</p>
-</div>
-<div class="pb" id="Page_22">22</div>
-<div class="img">
-<img src="images/i08.jpg" alt="Key to mural" width="800" height="582" />
-</div>
-<dl class="undent"><dt>1/Moropus</dt>
-<dt>2/Promerycochoerus</dt>
-<dt>3/Menoceras</dt>
-<dt>4/Oxydactylus</dt>
-<dt>5/Daphoenodon</dt>
-<dt>6/Stenomylus</dt>
-<dt>7/Dinohyus</dt>
-<dt>8/Merychyus</dt>
-<dt>9/Palaeocastor</dt>
-<dt>10/Parahippus</dt>
-<dt>11/Syndyoceras</dt></dl>
-<div class="pb" id="Page_23">23</div>
-<h3 id="c4">A Visit to the Past</h3>
-<p>Come enter into our imaginations and return to a
-day along the Niobrara River in western Nebraska
-20 million years ago. Let&rsquo;s go back and have an
-imaginary look. To set the mood, think about the
-wild animal movies made in modern Africa during
-the last 40 years. Think of a land swarming with life,
-of extensive grasslands dotted with trees through
-which great herds of grass- and leaf-eating animals
-are wandering. Look sharply into the shadows under
-the trees and amid the high grass where the meat-eaters
-are resting or stalking their prey. When you
-have this picture of wildlife in mind we&rsquo;re ready for
-our journey into the past.</p>
-<p>Projecting ourselves back those 20 millions of
-years, we find ourselves in a landscape filled with
-animals. Some of the animals are not much different
-from those living today, but others are so bizarre
-that you may have a hard time believing they really
-existed.</p>
-<p>Dawn is building a new day, and those animals
-which hunt and feed at night are disappearing into
-their lairs. There are so many kinds of livings to be
-made that the day isn&rsquo;t long enough for all animal
-varieties to be about and active only in daylight. As
-the light spreads over the land we see that it is an
-open, sunny place of mixed grasses and trees&mdash;mostly
-grassland, but here and there single trees or
-small clumps not big enough to be called groves. We
-would call it a savanna.</p>
-<p>A broad river runs through the land, and for lack
-of a better name we can call it the Niobrara or
-&ldquo;Running Water,&rdquo; the name given by Indians to the
-much smaller modern stream. This ancient Niobrara
-was a bold, wide stream with deep pools and sandbars.
-It was not cutting a valley as its modern counterpart
-is doing, but was carrying sand and silt down
-from the then-young Rocky Mountains. It sometimes
-flooded, and as it spread out over the wide, flat plain
-it deposited layers of sand and silt that geologists
-today call the Harrison Formation. The ancient
-Niobrara and other similar rivers spread the same
-sediments over nearby areas in eastern Wyoming
-and southwestern South Dakota. In the sediments,
-<span class="pb" id="Page_24">24</span>
-paleontologists would one day find millions of bones.</p>
-<p>Our ancient river was the center of life for untold
-numbers of animals. They lived in it, along its banks,
-in the willow thickets that grew on its more permanent
-sandbars, and on the broad, tree-dotted
-plains that stretched to the horizon beyond the river&rsquo;s
-normal course. Great herds of small horses, rhinoceroses,
-camels, and other dwellers on the savanna
-came to water holes to drink and perhaps to wallow
-in the cool and refreshing pools. Although all else
-might be anticlimactic, let&rsquo;s look at the rhinoceroses
-first.</p>
-<p>We know that in the modern world rhinos belong
-in Africa and southeastern Asia, not North America,
-yet this continent was the major home of these
-strange beasts for millions of years. Rhinos did not
-become extinct in North America until about 5 million
-years ago, during the Pliocene (see geologic time
-chart on <a href="#Page_46">page 46</a>). Along the ancient Niobrara the
-rhino herds are not made up of the giant mammals
-we see in zoos today. The ones we see moving slowly
-toward the river on this early Miocene day are no
-larger than big domestic pigs. They are the first
-among the rhinos to have horns&mdash;not one behind the
-other, but a pair near the end of the nose, side by
-side. To scientists today these rhinos are known as
-<i>Menoceras</i>. The name <i>Diceratherium</i>, once used both
-for these small rhinos and a larger type of ancient
-rhino, now refers accurately to just the large rhino.</p>
-<div class="img" id="fig11">
-<img src="images/i09.jpg" alt="" width="597" height="425" />
-<p class="pcap"><i>Menoceras</i></p>
-</div>
-<p>Look off to the south. There&rsquo;s a herd moving
-slowly but purposefully down to its favorite watering
-hole. You can see that the males have the paired
-nose horns, and that the females, which are about
-the same size, do not. Trotting amid the herd are fat
-little colts whose seriousness of purpose belies their
-youth. The herd seems to be made up of about 50
-individuals moving through the tall grass like a flattened
-dark gray cloud. Suddenly they are startled by
-a large cat or dog stalking through the grass, and all
-the males on the side nearest the enemy bunch together
-to face the hungry hunter. Most of the herd
-continues to flow across the plain, and when the
-danger is past the guardian males catch up in a lumbering
-gallop.</p>
-<p>Finally the herd reaches the river and spreads out
-through the shallows. It is hot today, and the flies
-are biting even through the tough rhino hides. Many
-<span class="pb" id="Page_25">25</span>
-of the adults go into deeper pools to roll and soak
-while the young drop their serious attitudes and frolic
-in the shallows.</p>
-<p>As the day wears on, the herd leaves the river and
-feeds on the leaves and stems of scattered trees and
-willow thickets along the river. When twilight comes,
-the herd draws together, colts and females toward
-the center and bulls around the edges. After a period
-of milling and pushing, the herd finally beds down
-for the night, with only the perimeter guards moving
-around on the edges.</p>
-<p>The daily routines of the other herds of grass- and
-leaf-eating animals generally follow somewhat different
-patterns from that of the rhinos. Of them,
-only the piglike oreodons wallow in the river. The
-others spend nearly all their time out on the savanna,
-coming to the river only at dawn or dusk to drink.</p>
-<p>Oreodons were among the most abundant
-medium-sized animals of the Middle Tertiary. A
-strictly North American group, they have been
-described as looking like a cross between a sheep
-and a pig. As small as a house cat or as big as a
-domestic pig, these mammals reached a peak in
-abundance and variety between the Middle and
-Late Oligocene (though they are known from the
-Late Eocene through the Late Miocene). This peak
-probably has never been equalled by any other
-group of mammals in such a size range.</p>
-<p>As we look out among the herds of animals dotting
-the plain, we can see only a few small bands of oreodons.
-There&rsquo;s a group coming toward us now.
-These are some big, ugly ones with large triangular-shaped
-heads. The backs of their cheek bones flare
-out far to the sides, so that with their narrow snouts
-they are most peculiar looking. Their bodies are long
-and rather nondescript, and their legs are short but
-slender. This particular kind is known as <i>Promerycochoerus</i>
-(&ldquo;before ruminant hog&rdquo;) and is just about
-the largest of the oreodons. They are really a rare
-sight here at Agate. Perhaps the large herds of
-<i>Menoceras</i> fill their ecologic niche locally, and the
-oreodons have found they cannot successfully compete
-with the rhinos for food, water, and living space.
-After all, not everything can fit into Paradise.</p>
-<div class="img" id="fig12">
-<img src="images/i09a.jpg" alt="" width="594" height="433" />
-<p class="pcap"><i>Promerycochoerus</i></p>
-</div>
-<p>Look to the northeast: there&rsquo;s a herd of <i>Miohippus</i>
-(&ldquo;Miocene horse&rdquo;) wading into the river to drink and
-browse in the willows along its banks. Let&rsquo;s walk
-<span class="pb" id="Page_26">26</span>
-toward the herd slowly and quietly. We should take
-an especially good look at this herd&mdash;they are part
-of a doomed race! The genus <i>Miohippus</i> is making
-its last stand at this time. When conditions change,
-well adapted species may restrict their ranges to what
-is left of the old environment; they may adapt, if
-they are able, to the new conditions; or they may
-not survive if they cannot adapt.</p>
-<p><i>Miohippus</i> did all these things. Some species of
-the genus became extinct. Some evolved into something
-else. But the end result was the complete termination
-of the genus <i>Miohippus</i> as paleontologists
-recognize it. Much of the environmental pressure
-coming to bear on the genus <i>Miohippus</i> was a result
-of mountain building to the west. As the young Rockies
-rose, rain-bearing winds from the oceans far to
-the west were wrung of their moisture. This same
-circumstance makes the high plains a land of little
-rain today.</p>
-<p>The scattered trees and groves we see from our
-vantage point of long ago will disappear and be replaced
-with a sea of drought-tolerant grasses. In effect,
-the savannas will give way to prairies. <i>Miohippus</i>
-will soon be yielding its place to descendants
-which can eat grass as a steady diet. Grass is much
-harsher on the teeth than the foliage that <i>Miohippus</i>
-eats. In eating grass, grazing animals pick up sand
-and silt enough to quickly wear away teeth designed
-for leaf-eating. The descendants of <i>Miohippus</i> will
-become better runners, too, with longer and more
-powerful legs. As the trees disappear there will no
-longer be friendly clumps of greenery to hide behind
-when hungry meat-eaters are on the prowl. From
-now on, fleetness of foot will be a most important
-factor in horse survival.</p>
-<p><i>Miohippus</i> will also give rise to somewhat larger
-forest horses that will survive on into the Pliocene
-in patches of woodland. They will be little changed
-except in size (some came to be nearly as large as
-the modern horse), and some of them will even cross
-the Bering Land Bridge into Eurasia. This is the last
-time, however, that we&rsquo;ll see these primitive horses
-in large numbers here in North America.</p>
-<p>There&rsquo;s another herd of small horses moving
-across the plain toward the river from the south.
-These are feeding as they move across the savanna,
-eating both leaves from the scattered trees and grass
-<span class="pb" id="Page_27">27</span>
-from the prairie. They seem to be enjoying their
-mixed diet and thriving on it, so they won&rsquo;t be too
-badly hurt in the geologically near future when they
-have to eat mostly grass. This is <i>Parahippus</i> (&ldquo;near
-horse&rdquo;), a new kind of horse just recently evolved
-from <i>Miohippus</i>.</p>
-<div class="img" id="fig13">
-<img src="images/i10.jpg" alt="" width="600" height="427" />
-<p class="pcap"><i>Parahippus</i></p>
-</div>
-<p><i>Parahippus</i> is a horse of destiny. For a long time
-some individuals of <i>Miohippus</i> carried a little extra
-wrinkle of enamel on the crowns of their upper grinding
-teeth&mdash;and now the wrinkle occurs in all individuals
-of <i>Parahippus</i>. Because of it, <i>Parahippus</i> can
-eat grass without wearing out its teeth before reaching
-breeding age, making it possible for most individuals
-to reproduce before dying. The little wrinkle
-is passed on. It&rsquo;s only a small advantage, but such
-is the stuff that survival and evolution are made of.
-<i>Parahippus</i> is the forerunner of a vast array of different
-three-toed, long-limbed prairie horses that
-will be the most numerous members of their family
-until nearly the end of the Pliocene. From one of
-their descendants will come the first one-toed horse&mdash;the
-direct ancestor of our modern horses.</p>
-<p>More herds are moving in on the river as the morning
-grows. There&rsquo;s a group of something very small
-moving through the tall grass, but it&rsquo;s completely
-hidden. Only the swaying of the 60-centimeter-tall
-blades shows that a number of animals are hurrying
-toward the river. Now they&rsquo;ve moved out into an
-area of cropped grass, and we can see a herd of the
-diminutive deerlike <i>Nanotragulus</i> (&ldquo;dwarf goat&rdquo;).
-Not a great deal larger than a house cat, these little
-&ldquo;deer&rdquo; have tall grinding teeth well adapted for
-grass-eating. Their ancestry goes back for millions
-of years into the Late Eocene, when some of their
-ancestors stood less than 15 centimeters (6 inches)
-high at the shoulder. But their entire family is soon
-to become extinct. They are part of the grazing
-community, although they eat leaves and softer
-vegetation just as readily. We call them &ldquo;deer&rdquo;
-because they look just like miniature deer, but the
-two families are really only distantly related.</p>
-<p>As this group scampers toward the river, we can
-see that they have a peculiar crouching gait&mdash;their
-forelegs are so much shorter than their hind legs that
-they seem to be running continuously downhill. They
-are dainty little animals with small, delicate heads
-and short, slender limbs. They can bound swiftly
-<span class="pb" id="Page_28">28</span>
-away if danger threatens, but they&rsquo;d rather hide in
-the thick brush. A few of the females have fawns
-with them, tiny things less than 10 centimeters (4
-inches) tall. Look at them all scatter! The shadow
-of a hawk has passed over the group, and in their
-fright they&rsquo;ve dived for some nearby willows. Young
-<i>Nanotragulus</i> either learn to duck down at the sight
-of a passing shadow or they don&rsquo;t get a chance to
-learn at all. This time they all got away, and the
-hawk will have to look elsewhere for a meal.</p>
-<p>Buteos or buzzard hawks are common along the
-Niobrara in the Early Miocene, sailing on the warm
-updrafts on broad, short wings that let them ride the
-lightest airs. They swoop down on the mice and
-pocket gophers, young rabbits and beavers, baby
-&ldquo;deer&rdquo; and sometimes careless birds that live on this
-savanna. All manner of meat-eaters depend on the
-small animals for food, and the little <i>Nanotragulus</i>
-are most vulnerable as they move through the canopy
-of grass.</p>
-<p>There don&rsquo;t seem to be any other herds moving
-into view just now; but while we&rsquo;re on the subject
-of birds, over there in that patch of short grass is a
-bird rarely seen in North America anymore. It&rsquo;s a
-guan, a ground-living bird related to the grouse and
-sagehens. It must be far from home this morning;
-most of its time is spent in the thick brush farther
-back from the river. A heavy body and long neck
-and tail make this animal easy to identify.</p>
-<div class="img" id="fig14">
-<img src="images/i11.jpg" alt="" width="598" height="431" />
-<p class="pcap"><i>Oxydactylus</i></p>
-</div>
-<p>Let&rsquo;s look at some of the individuals and small
-groups that are moving or resting within view. The
-camels with the very slender legs and long necks are
-called <i>Oxydactylus</i> (&ldquo;sharp finger&rdquo;). They are
-browsing on the willows where the herd of Nanotragulus
-ran to hide. <i>Oxydactylus</i> is an important camel,
-standing about at the midpoint in the evolution of
-this North American family of mammals. The camels
-will remain stay-at-homes in the continent of their
-origin until they spread into Eurasia and South
-America at the beginning of the Pleistocene Epoch,
-some 17.5 million years after the rhinos died out at
-Agate. There are many species of <i>Oxydactylus</i>; the
-one we are looking at stands about 1.2 meters (4
-feet) high at the shoulder. Notice that they don&rsquo;t
-have humps on their backs; in this lush land there
-is no need to store fat against a time of possible
-starvation.</p>
-<div class="pb" id="Page_29">29</div>
-<div class="img" id="fig15">
-<img src="images/i11a.jpg" alt="" width="595" height="429" />
-<p class="pcap"><i>Stenomylus</i></p>
-</div>
-<p>Speaking of camels, here comes a herd of <i>Stenomylus</i>
-(&ldquo;narrow tooth&rdquo;) bounding through the tall
-grass on the south bank of the river. This is a strange
-little long-neck camel that strayed off the main line
-of the family&rsquo;s evolution. Less than 60 centimeters
-(24 inches) high at the shoulder, it looks very much
-like the living African antelope called the gerenuk.
-<i>Stenomylus</i>, with its long and delicate legs and tall
-cheek-teeth, is perfectly adapted for living in and
-eating the abundant grass which billows on this tree-dotted
-plain. Yet many of the little <i>Stenomylus</i> are
-going to share a tragic time with hundreds of
-<i>Menoceras</i> only a year or so from this day we are
-visiting. Later, we&rsquo;ll move ahead to that time so you
-can see that natural disaster, now preserved in rock,
-as it happened.</p>
-<p>When you travel back 20 million years in time you
-would expect to find unbelievably bizarre animals.
-So far, we&rsquo;ve seen some offbeat specimens, but there
-has been nothing really out of this world. Now, if
-you look to the north by the lone oak tree, you will
-see a real prize. Do you see that hulk stepping out
-of the shade? No, it isn&rsquo;t the Dragon of the Ishtar
-Gate, though it might pass for a mythical beast. What
-a wonderful animal! A head like a large horse&rsquo;s, a
-neck somewhat slimmer, long front legs, sloping
-back, short hind legs, and a little switch tail. Watch
-with your field glasses when it moves out onto the
-bare ground. See the feet? They don&rsquo;t have hooves;
-each toe ends in a great curved claw! This is one of
-the fabulous chalicotheres, a relative of the horses
-and the rhinos. There were never very many of them
-living at one time, but the family lived in Eurasia
-from the Eocene, some 55 million years ago, through
-the Pleistocene; and here in North America from
-the Late Eocene to the Middle Miocene.</p>
-<div class="img" id="fig16">
-<img src="images/i11b.jpg" alt="" width="597" height="434" />
-<p class="pcap"><i>Moropus</i></p>
-</div>
-<p>This chalicothere is named <i>Moropus</i> (&ldquo;sloth foot&rdquo;),
-and it is little wonder that when paleontologists first
-discovered his foot bones (without an associated
-skull) they thought they had found the feet of a
-ground sloth. Let&rsquo;s watch <i>Moropus</i> as it ambles
-slowly across the plain, its strange stilted walk a little
-like that of the modern giraffe. Other animals move
-aside as <i>Moropus</i> strides through the grass. He&rsquo;s a
-browser, an occasional grass-eater, and even a digger
-of easily accessible roots and tubers. Like his cousins
-the rhinos, he isn&rsquo;t at all bright, and he has a very
-<span class="pb" id="Page_30">30</span>
-short temper. When he&rsquo;s annoyed, he kicks out with
-those claws and every animal with good sense leaves
-him alone. He&rsquo;s respected by meat-eaters and plant-eaters
-alike. He walks by himself and everything else
-detours around him.</p>
-<div class="img" id="fig17">
-<img src="images/i12.jpg" alt="" width="594" height="424" />
-<p class="pcap"><i>Dinohyus</i></p>
-</div>
-<p>Look down toward the river, and we may see an
-exception. That two-meter (six-foot) high &ldquo;pig&rdquo;
-walking away from the river, covered with mud, is
-heading right toward the <i>Moropus</i>. His name is <i>Dinohyus</i>
-(&ldquo;terrible pig&rdquo;), and he&rsquo;s just as short-tempered
-and stupid as <i>Moropus</i>. He looks like a giant
-peccary, but his size and over-large head give him
-away as an entelodont (&ldquo;complete tooth&rdquo;). These
-are pig-like animals, usually of large size, that aren&rsquo;t
-related to the domestic pigs at all. <i>Dinohyus&rsquo;</i> skull
-is nearly one meter (three feet) long, and those tusks
-are as thick as a man&rsquo;s wrist. Though we missed
-seeing him earlier, he must have been wallowing in
-the mud under the overhanging willows. Now he&rsquo;s
-heading away from the river in search of lunch. He&rsquo;s
-not very choosy about what he eats; it might be succulent
-leaves or fruits, or even the carcass of a dead
-animal. <i>Dinohyus</i> is an omnivore, eating almost anything
-that has nourishment.</p>
-<p>Right now it looks as though he&rsquo;s on a collision
-course with the <i>Moropus</i>. He&rsquo;s seen the larger animal,
-has stopped in his tracks, and is pawing the
-ground with his front feet. Up goes his head&mdash;and
-listen to that roar! He&rsquo;s getting a good temper
-worked up. Off he goes at a full gallop, right toward
-the <i>Moropus</i>. It&rsquo;s hard to believe that an animal as
-big as that pig could charge so fast. And look at the
-<i>Moropus</i>! He&rsquo;s finally realized in his dim way that
-he&rsquo;s about to be attacked. Up he goes on his hind
-legs, holding his front legs out ready for a downward
-blow with all eight claws. But suddenly <i>Dinohyus</i>
-shifts his course just slightly, lets out another loud
-bellow as he avoids the <i>Moropus</i>, and thunders off
-toward the open prairie.</p>
-<p><i>Dinohyus</i> has a smaller relative around here somewhere,
-a little fellow just over one meter (three feet)
-high, called <i>Entelodon</i>. His head is long and low and
-has flaring cheekbones and bumps along the underside
-of the jaw like his larger cousin&rsquo;s. Another pig
-that lives along the Niobrara is <i>Desmathyus</i> (&ldquo;bond
-[filling a gap] pig&rdquo;), a true North American pig or
-peccary. Its appearance probably wouldn&rsquo;t surprise
-<span class="pb" id="Page_31">31</span>
-anyone; it looks very much like the peccaries that
-live in the American Southwest today. Its distant
-cousin, the domestic pig, was domesticated in the
-Old World from a European species of wild hog, and
-it was spread throughout the world by European
-colonists. In America, peccary evolution has run a
-long and conservative path. This group has changed
-relatively little in the 35 million years since it first
-appeared in the Late Eocene.</p>
-<div class="img" id="fig18">
-<img src="images/i12a.jpg" alt="" width="602" height="422" />
-<p class="pcap"><i>Syndyoceras</i></p>
-</div>
-<p>Now for another weird and wonderful beast! Trotting
-daintily out of a thicket on our left is a herd of
-something you might think were deer or pronghorn.
-But if you look closely you&rsquo;ll see that they have two
-pairs of curving, unbranched horns on their heads,
-not the single pair of prongs you&rsquo;d expect on a pronghorn.
-These are <i>Syndyoceras</i> (&ldquo;together horn&rdquo;),
-members of a family of mammals found only in
-North America and now extinct. Even on the Early
-Miocene day we&rsquo;re visiting, they are scarce, moving
-only in small herds. The rear pair of horns is not
-remarkable, but the front ones, which rise from a
-large bump near the nose, curl up and away from
-each other, ending in blunt tips.</p>
-<p>The first member of this family was <i>Protoceras</i>,
-which lived in the hills and mountains of western
-South Dakota during the Late Oligocene, just a few
-million years before the day we are visiting at Agate.
-Paleontologists have found battered scraps of its
-skeletons in the White River Badlands where perhaps
-they were washed by heavy spring rains running
-off the hills to the west. <i>Protoceras</i> had six bony
-bumps on its head that presumably bore short horns;
-one pair was over the nose, another was over the
-eyes, and a third was near the back of the skull.
-Probably it was the direct ancestor of <i>Syndyoceras</i>.</p>
-<p>If <i>Syndyoceras</i> fails somehow to qualify as grotesque,
-let&rsquo;s jump a few million years into the &ldquo;future&rdquo;
-and look at his Late Miocene descendant, <i>Synthetoceras</i>
-(&ldquo;combined horn&rdquo;). Here was an animal
-on a par with unicorns and cyclopses. Like <i>Syndyoceras</i>
-he had two tall horns at the back of his head;
-but something had happened to the curved ones on
-his nose. They had, during several million years of
-evolution, grown together into a single shaft and
-then spread out again to the sides and up. What a
-pity there were no little boys then, for here we have
-the world&rsquo;s first and only self-propelled slingshot!
-<span class="pb" id="Page_32">32</span>
-Tie a rubber band to the tips of his nose horns, fill
-your pocket with pebbles, and saddle up.</p>
-<p>You may be wondering by now about the smaller
-animals&mdash;the rodents and small carnivores. We have
-not seen any of them so far. Most carnivores work
-at night, but there should be a few about. Down by
-the river is a pair of <i>Oligobunis</i> (&ldquo;little cusp&rdquo;) hunting
-near the water&rsquo;s edge. They look something like
-modern badgers but are really more closely related
-to the weasels. If you look just to the right of the
-herd of <i>Stenomylus</i> we were following earlier you
-might be able to catch a glimpse of a stalking cat
-about the size of a mountain lion. It&rsquo;s probably either
-an advanced <i>Nimravus</i> (&ldquo;ancestral hunter&rdquo;) or an
-early <i>Pseudaelurus</i> (&ldquo;false cat&rdquo;), but we&rsquo;ll have to
-get a closer look before we can be sure. Whichever
-it is, it&rsquo;s on the main line of cat evolution and will
-eventually end up in our familiar <i>Felis</i> and the other
-living cats. There should also be some sabretooth
-cats lurking about; they are found in nearby deposits
-of the same age, though not at Agate itself.</p>
-<div class="img" id="fig19">
-<img src="images/i13.jpg" alt="" width="601" height="434" />
-<p class="pcap"><i>Daphoenodon</i></p>
-</div>
-<p>If you look very closely at the thicket just south
-of us on the hillside you can see several fox-like dogs
-hunting rodents. This <i>Nothocyon</i> (&ldquo;false dog&rdquo;)
-seems to have filled approximately the fox niche
-during the Early Miocene. Some coyote and wolf-sized
-dogs are in the area too. <i>Daphoenodon</i> (&ldquo;blood-reeking
-tooth&rdquo;) is about coyote size. <i>Temnocyon</i>
-(&ldquo;cutting [tooth] dog&rdquo;), is a little larger, probably
-substituted for the wolf in the local fauna, and is
-characterized by its heavy head and long, strong
-jaws. If we could get a close look at its teeth, we
-would see that they are like those of the Cape Hunting
-Dog living today in South Africa.</p>
-<p>Let&rsquo;s move away from the river a half-kilometer
-(0.3 mile) or so and see if we can find something
-different. That thicket ahead might produce a couple
-of rabbits. Look, there at the edge of the thicket: a
-<i>Nothocyon</i> has caught something. It&rsquo;s a <i>Meniscomys</i>
-(&ldquo;crescent mouse&rdquo;), an early relative of the living
-mountain beaver <i>Aplodontia</i>. Today, a single species
-of <i>Aplodontia</i>, the last of the line, is found only in
-the mountains of the West Coast. It&rsquo;s the most primitive
-living rodent, not related to the Canadian
-beaver, and sole survivor of a suborder which was
-the earliest rodent group to evolve. <i>Meniscomys</i> was
-one of the most prominent members of the group
-<span class="pb" id="Page_33">33</span>
-during the Miocene. It had a round furry body, a
-round head with protruding incisors a bit like a true
-beaver&rsquo;s, and no visible tail.</p>
-<p>Watch your step. There is the mound of a pocket
-gopher. It is neither our familiar western gopher
-<i>Thomomys</i> (&ldquo;heap mouse&rdquo;) or the &ldquo;eastern&rdquo; pocket
-gopher of the Great Plains, <i>Geomys</i> (&ldquo;earth mouse&rdquo;),
-but an ancient relative, <i>Gregorymys</i> (&ldquo;Gregory&rsquo;s
-mouse&rdquo;). It must be pretty successful as a burrowing
-animal, because we find it all over the western
-United States in the Early Miocene.</p>
-<div class="img" id="fig20">
-<img src="images/i13a.jpg" alt="" width="602" height="425" />
-<p class="pcap"><i>Palaeocastor</i></p>
-</div>
-<p>A hundred meters (300 feet) more and we&rsquo;ll show
-you the surprise of the day. Here we are in what
-looks like a prairie dog town. But those aren&rsquo;t prairie
-dogs. They&rsquo;re a little larger, and quite unfamiliar by
-modern standards. Can&rsquo;t guess what they are? These
-are beavers&mdash;<i>Palaeocastor</i> (&ldquo;ancient beaver&rdquo;) to be
-exact. Here in the Early Miocene of North America,
-beavers don&rsquo;t build dams. In fact they live neither
-at the water&rsquo;s edge nor, like muskrats, in the water.
-They dig deep, spiral burrows in well drained
-ground. Some of their burrows are 2.5 meters (8
-feet) deep, but 2 meters (6.5 feet) is about average.
-Down and around and around the burrows go, like
-giant corkscrews, always ending in straight shafts
-slanting slightly upward so that living chambers will
-not be flooded by rainwater running down the burrows.</p>
-<p>Paleontologists have called the preserved burrows
-&ldquo;devil&rsquo;s corkscrews&rdquo;&mdash;<i>Daemonelix</i>&mdash;since the time
-they were first found. At first, scientists thought they
-might be holes left by the giant tap roots of some
-unknown plant. But when <i>Palaeocastor</i> skeletons
-were found in the bottoms of the spirals, almost
-everyone had to concede that they were truly beaver
-burrows. Admittedly, the skeleton of a <i>Nothocyon</i>
-was found in one burrow; but this predator probably
-followed a beaver home for supper and just stayed.
-Three other kinds of beavers lived around Agate in
-the Early Miocene, but their bones have never been
-found in the burrows. No one knows what they did
-for homes: perhaps their burrows were much shallower
-or were in the river banks where running water
-soon destroyed them.</p>
-<p>Near the river bank in some soft sand is a nest of
-tortoise eggs. The hot sun has brought the babies
-out of their shells and they&rsquo;re stumbling off in all
-<span class="pb" id="Page_34">34</span>
-directions. Right now the biggest is only about twice
-the size of a silver dollar; but when they&rsquo;re grown
-they&rsquo;ll be about 60 centimeters (24 inches) across the
-shell, or perhaps even larger. They&rsquo;re strict vegetarians,
-grazing and browsing on soft plants and
-leaves. There are probably some pond turtles around
-too, but we&rsquo;ve never seen any.</p>
-<p>A little farther up the bank, under the roots of
-that big walnut tree, is a rabbit&rsquo;s burrow. Several
-<i>Palaeolagus</i> (&ldquo;ancient rabbit&rdquo;) live there with their
-many offspring. Although they look very much like
-cottontails, their ears are smaller and they haven&rsquo;t
-the same leaping and running ability. They&rsquo;d much
-rather hide than flee their enemies.</p>
-<p class="tb">These dwellers of the savanna, common during
-the Miocene Epoch, comprise the major species
-found at the Agate Fossil Beds. Their discovery in
-the late 1800&rsquo;s and early 1900&rsquo;s was highly important
-to the young science of paleontology. In those
-decades of major discoveries, large gaps remained
-in the story of evolution. Quarries like those at
-Agate helped provide the missing pieces of the
-puzzle. In their time, the discoveries at Agate were
-an important contribution toward understanding
-the world far beyond the dawn of mankind.</p>
-<p>Today, advances in paleontology still depend primarily
-upon major field discoveries, but paleontologists
-also make use of highly refined analytical and
-measurement techniques. Closely connected with
-paleontology are several other sciences, among them
-geology, zoology, and botany. The paleontologist,
-for example, must depend on geology to provide
-important answers about the age of fossil specimens.
-Fossil botanical specimens, in turn, can provide answers
-about animal diets and climate. Though paleontology
-may center on the study of fossil remains,
-it is an interdisciplinary science. This fact will become
-increasingly apparent in the following chapters,
-which reveal the strands of evidence used in
-constructing the picture of Miocene Agate.</p>
-<div class="pb" id="Page_35">35</div>
-<h3 id="c5">The Mark of Death Upon the Land</h3>
-<p>Even in Paradise an occasional calamity can occur.
-Agate&rsquo;s misfortune appeared in the form of a
-drought. To the west of the plain built by the ancient
-Niobrara River, the Rocky Mountains began to rise
-again. This renewed uplift, after millions of years of
-relative quiet, eventually led to an even drier climate
-and a replacement of the savanna with a landscape
-of unbroken grasslands from the mountains to the
-Mississippi River and beyond. Trees then could survive
-only on canyon slopes along the courses of the
-few large remaining rivers that crossed the plains.
-Those rivers flowed toward the central lowlands of
-North America, once an embayment of the Gulf of
-Mexico. This Mississippi Embayment, as it is called
-by geologists, extended as far north as the present
-location of Cairo, Illinois.</p>
-<p>During the first rumbles of this upheaval there
-were occasional instabilities in the weather of the
-Great Plains. From the fossil evidence of Carnegie
-Hill, University Hill, and the <i>Stenomylus</i> quarry, we
-can see that drought touched the land.</p>
-<p>What happens when disaster stalks the land? That
-question, so pertinent to an understanding of fossil
-deposition at Agate, can be answered best by looking
-at the normal scheme of life. Animal populations
-are cyclic, increasing rapidly to near the highest numbers
-which can be supported on available food supplies.
-If times are good, animal populations can be
-quite high. If the food supply decreases, massive
-dieoffs result. Successive cycles of plenty and poverty
-then produce high populations followed by dieoffs.</p>
-<p>The fossil evidence suggests that a prolonged
-drought occurred during the Golden Age at Agate,
-resulting in death everywhere. The vast numbers of
-rhino skeletons preserved at Carnegie Hill and
-University Hill provide paleontological evidence
-that the drought must have lasted for several years.</p>
-<p>Climates change slowly, and there are wet and dry
-cycles. Every rancher and farmer discovers this when
-he plows new land during a wet cycle, for sooner or
-later drier years catch up with him. He expects the
-optimum to be the standard; but he is badly hurt
-during average times, and really suffers when the
-<span class="pb" id="Page_36">36</span>
-dry years come. It is the same with populations of
-wild animals. When the times are good and the grass
-and trees are lush, fat, and green, more of the young
-survive and the whole population flourishes. The
-plant-eaters expand their herds and the meat-eaters
-increase to keep up with the better food supply the
-plant-eaters provide. In each case the standards for
-survival are lowered, and the less than perfect can
-survive and in turn produce young of their own. But
-when the water fails and plants refuse to grow, the
-herbivores starve and the carnivore population in
-turn declines. Nature is indifferent&mdash;neither cruel
-nor kind. When times are bad every species is improved,
-for the strongest and most tenacious survive
-to reproduce themselves. There are benefits to hardship.</p>
-<p>So it was at Agate only a year or so after the day
-of our visit. The river died for a while. As with many
-rivers much of its water flowed beneath the surface,
-through the sand and gravel of the bed. When the
-ancient Niobrara died there was still water moving
-through the sands and filling the low spots in its bed.
-Some animals could dig down to it and survive,
-others could stake claims to the diminishing water
-holes. So the thirsty, suffering herds of <i>Menoceras</i>
-went to the river and found no water. The strong
-held the water holes. The smart dug into the sand
-and made their own water holes. The rest died. They
-died by the hundreds, and thousands. Mixed with
-the carcasses of <i>Menoceras</i> were other victims: occasional
-chalicotheres, giant pigs, oreodons, cats, dogs,
-and a variety of equally thirsty smaller animals. Perhaps
-most of the animals went farther up or down
-stream, or perhaps they chose not to die at the river.
-Whatever the pattern of dying might have been, we
-know that <i>Menoceras</i> left untold numbers of skeletons
-on the broad, flat, and dry bottom of the ancient
-Niobrara.</p>
-<p>Finally the rains fell in the mountains to the west.
-The river filled with water again and ran in sheets
-across the plain. At Agate the millions of <i>Menoceras</i>
-bones and lesser numbers of the bones of other animals
-were swept for a few hundred meters downstream
-and into some sort of backwater or river
-lake&mdash;possibly a great meander, or an oxbow lake.
-There, like a gigantic mass of jackstraws, they were
-piled in a tangled mat 30 centimeters (12 inches)
-<span class="pb" id="Page_37">37</span>
-thick, covering an unknown number of hectares. All
-we really know is that they were moved far enough
-to get thoroughly jumbled, but not far enough to be
-badly broken or much eroded by the action of the
-water.</p>
-<p>The mass of bones was soon buried by the sands
-and silts dropped by the reborn river, and by wind-carried
-debris swept off the parched land. Once buried,
-the bones were partially petrified by mineral
-water flowing beneath the surface. The land was built
-up a few hundred meters by sediments continually
-brought down from the mountains to the west. Eventually,
-continued uplifts of the Rockies and the Great
-Plains combined with erosional cycles to leave the
-modern Niobrara River. The two erosional remnants
-known today as Carnegie and University Hills were
-produced by the cutting of the modern river system.
-On the sides of these hills were exposed the tangle
-of bones which marked the site of ancient tragedy.</p>
-<p>But this wasn&rsquo;t the only scene of mass death to be
-preserved here in the fossil record. A few kilometers
-away an earlier drought took a toll of many other
-animals. The little gazelle-like camel <i>Stenomylus</i>
-tells the same story in scores of skeletons east of the
-<i>Menoceras</i> burial ground.</p>
-<p>These graceful little camels may have died at the
-edges of their vanished water hole. The skeletons
-are mostly undisturbed except for a few pulled apart
-by meat-eaters. Scores of their dried out, mummified
-carcasses were buried about the same time as
-the rhinos on the river&rsquo;s dry bottom. Like the
-<i>Menoceras</i>, the camels lay there for millions of years,
-intact in their death poses, the muscles in the backs
-of their necks pulling their heads back sharply into
-an unnatural position. There they lay until men discovered
-them.</p>
-<p>Our imaginary journey into the past has reached
-its end. We have seen a day at Agate as it might
-have been 20 million years ago. We have watched
-the animals going about their daily lives during times
-of plenty and have seen it as it was later, when
-death&rsquo;s heavy hand left a magnificent fossil heritage.
-This unique place is a window into the past, a window
-through which we can look back at any time and
-observe life at Agate millions of years ago.</p>
-<div class="pb" id="Page_38">38</div>
-<h3 class="interlude">Excavations at Agate Springs</h3>
-<blockquote>
-<p>The first fossils were collected in volume in 1904 by Olaf
-Peterson of the Carnegie Museum in Pittsburgh. Excavations
-have continued, off and on, to the present. As
-early as 1892, Erwin Barbour&rsquo;s student F. C. Kenyon had
-retrieved a few bones from the site but their significance
-was overlooked. Rancher James Cook first picked some
-up in the 1880s and may have first noticed such
-deposits, without particularly recognizing them, in the 1870s.</p>
-<p>Other institutions soon joined Carnegie in extracting slabs
-of the great <i>Menoceras</i> bone-bed, and occasional <i>Moropus</i>
-and <i>Dinohyus</i> specimens. The University of Nebraska
-opened a new quarry in 1905. Henry Fairfield Osborn, president
-of the American Museum of Natural History
-and one of the greatest popularizers and exponents of
-evolutionary science, and his chief preparator Albert
-Thomson began work in 1907. F. B. Loomis of Amherst
-College discovered the nearby <i>Stenomylus</i> quarry the same
-year. Yale University&rsquo;s R. S. Lull soon followed.</p>
-<p>From 1911 to 1923 the American Museum became
-the main excavator at Agate, but increasingly their attention
-was drawn elsewhere, including the later Miocene
-Snake Creek Beds 20 miles to the south. There, for awhile,
-great excitement centered around a worn tooth thought
-to be from an early human ancestor until the tooth was
-proven to be from an ancient peccary.</p>
-<p>Until 1981, only occasional excavations for bonebed slabs
-and <i>Stenomylus</i> marked the next 50 years. Then, Robert
-M. Hunt Jr. of the University of Nebraska reopened the
-main quarries and a little-known side area, and found
-evidence of an extensive carnivore den of the beardog
-<i>Daphoenodon</i>.</p>
-<p>In some cases, individual fossil
-bones were removed one by
-one, a very slow and painstaking
-process but when possible
-large blocks of fossil-bearing
-sediments were
-removed and shipped to laboratories
-for cleaning and
-analysis. The tools, chemicals,
-and special conditions necessary
-to extract the best specimens
-and most complete
-information are available only
-in a laboratory such as the
-one which is shown on pages
-<a class="pgref" href="#Page_40">40</a> and 41 at the Carnegie
-Museum in Pittsburgh, Pennsylvania,
-in 1905. Slabs from
-Agate Fossil Beds were taken
-there so paleontologists could
-examine the evidence and
-figure out the past.</p>
-<p>See pages <a class="pgref" href="#Page_86">86</a>-87 for a listing
-of museums with specimens
-from Agate Fossil Beds.</p>
-<div class="img">
-<img src="images/i14.jpg" alt="Extracting a slab" width="717" height="524" />
-</div>
-<div class="pb" id="Page_39">39</div>
-<div class="img" id="fig21">
-<img src="images/i14a.jpg" alt="" width="800" height="585" />
-<p class="pcap">Members of Peterson&rsquo;s crew
-built a box around a slab in the <span class="noti">Stenomylus</span>
-quarry around 1908 in preparation
-for shipping to the Carnegie Museum.</p>
-</div>
-<div class="img" id="fig22">
-<img src="images/i14c.jpg" alt="" width="800" height="585" />
-<p class="pcap">With a team of horses,
-O. A. Peterson&rsquo;s field crew
-moves dirt out of the <span class="noti">Stenomylus</span>
-quarry around 1908.
-The boxes in the foreground
-are resting on the
-quarry&rsquo;s lower bone layer.
-Several specimens to the
-left have been strengthened
-with plaster for shipment to
-Pittsburgh.</p>
-</div>
-<div class="img" id="fig23">
-<img src="images/i14d.jpg" alt="" width="800" height="593" />
-<p class="pcap">Crates of prepared specimens
-had to be taken to Harrison,
-37 kilometers (23 miles) north
-of Agate for the rail trip to the
-East. Note that the wagon is
-just a flat platform and that
-the driver is using the largest
-crate as a seat.</p>
-</div>
-</blockquote>
-<div class="pb" id="Page_40">40</div>
-<div class="img">
-<img src="images/i15.jpg" alt="Paleological laboratory." width="1000" height="740" />
-</div>
-<div class="pb" id="Page_42">42</div>
-<h3 class="interlude">The Beginnings of Paleontology</h3>
-<blockquote>
-<p>Paleontology is the study of
-ancient life through the fossil
-remains of that life. Today,
-there are thousands of museums,
-societies, professional
-groups, and academic institutions
-around the world devoted
-to this study. Fossil remains
-are still being dug out
-of the ground in a number of
-localities, such as Dinosaur
-National Monument in Utah,
-but by far the great bulk of
-fossils now being studied were
-excavated during the last 100
-years.</p>
-<p>There are now about 250,000
-known separate species of
-fossil plants and animals. Biologists
-are still working to
-explore, find, and classify all
-living species; they estimate
-that 4,500,000 species of
-plants and animals are now
-living at our own brief moment
-in the nearly five billion
-years of our planet&rsquo;s history.
-As you can see, the fossils
-now known represent only a
-tiny fraction of all the plants
-and animals that have ever
-lived. Yet a great deal is now
-known about even the simple
-forms of life more than three
-billion years ago.</p>
-<p>How has this come about?
-What has happened since the
-days of our great-grandfathers
-to cause this vast increase in
-knowledge? Men must have
-picked up and discussed fossils
-for tens or perhaps
-hundreds of thousands of
-years. We have no way of
-knowing what the earliest
-men thought about them.
-Their significance has been
-revealed slowly in the way we
-tend to look at time, but perhaps
-not so slowly when we
-consider how short a period
-man himself has been on
-Earth.</p>
-<p>Lucretius, a Roman writer of
-the first century B.C.,
-thought that the Earth was
-very young. He interpreted
-the fossils known to him as
-the remains of monsters that
-had grown out of the Earth
-just after it came into existence.
-Evidently he had seen
-partial fossils and believed
-them to be whole, because he
-postulated that the Earth had
-brought forth creatures that
-lacked one or more limbs or
-other body parts. Lucretius
-assumed, as have many
-others, that the varieties of
-animals he knew of were
-fixed for all time and did not
-change. But he did recognize
-the principle of evolution,
-that things change as time
-goes on, in his description of
-human history.</p>
-<p>Lucretius described four ages
-of human life, progressing
-from early hunters up to the
-highly civilized life he knew
-under the Roman Republic.
-His work was rediscovered
-during the European Renaissance,
-when scholars once
-again began to inquire into
-the nature of seemingly
-inexplicable things like fossils.</p>
-<p>Toward the end of the 18th
-century the confusion over
-the importance of fossils and
-their relative antiquity forced
-a scientific showdown. For
-hundreds of years, fossil
-bones of extinct animals unlike
-any ever seen had been
-turning up, often with tools
-nearby that appeared to have
-been shaped by human hands.
-A growing feeling that the
-Earth and therefore the fossils
-were very old indeed was a
-topic of frequent discussion in
-Europe and in the New
-World, despite the assertion
-by Archbishop Ussher a century
-earlier that the Earth was
-not quite 6,000 years old.</p>
-<p>Explorers and scientists had
-found fossils in deep layers of
-rock widely separated by
-other layers of rock, leading
-many of them to conclude
-that now-extinct forms of life
-had existed before the Biblical
-flood. A pioneer French
-paleontologist, Georges Cuvier,
-tried to solve this dilemma
-in the late 1700s by
-postulating that there must
-have been several worldwide
-floods before the one described
-in the Christian Bible.
-Finally, this solution collapsed
-under the weight of new evidence
-as more and more studies
-proceeded.</p>
-<p>In the 1830s an English geologist,
-Sir Charles Lyell, popularized
-the principle of uniformitarianism&mdash;the
-idea that
-processes we observe now,
-such as the steady erosion of
-mountains, the gradual
-buildup of silt as sediments in
-rivers, lakes, and oceans,
-have always occurred since
-the origin of the Earth. This,
-he then reasoned, meant that
-the Earth must be many millions
-of years old at least, instead
-of merely a few thousand
-years old.</p>
-<p>A wave of interest in fossils
-and their antiquity swept
-communities around the
-world in the 1840s and 1850s.
-Americans interested in science
-from Thomas Jefferson
-on had advocated the collection
-and study of fossils, and
-a feverish race to build up
-study collections got underway
-that lasted into the 20th
-century. Today, scientists believe
-the Earth is more than
-4.5 billion years old, its life
-more than 3 billion years old.</p>
-<div class="pb" id="Page_43">43</div>
-<div class="img" id="fig24">
-<img src="images/i16.jpg" alt="" width="386" height="600" />
-<p class="pcap"><b>Karl Von Linn&eacute;</b>, 1707-1778, is
-known as Linnaeus after the
-Latin form of his name. A
-Swedish botanist, he established
-a hierarchical system for
-classifying plants and animals
-that is still in use in a modified
-form. His organizing principle
-was the degree of complexity
-of the organisms he studied.
-This resulted in a system with
-seven levels: Kingdom, Phylum,
-Class, Order, Family,
-Genus, and Species, in descending
-order from the
-broadest category to the most
-specific. Students remember
-the system by the sentence
-&ldquo;King Philip Crossed the
-Ocean For Good Soup.&rdquo;
-Without realizing it, Linnaeus
-prepared the ground for the
-evolutionists, who later were
-able to demonstrate the gradual
-ascent of life forms from
-simple to complex by using his
-scheme of classification.</p>
-</div>
-<div class="img" id="fig25">
-<img src="images/i16a.jpg" alt="" width="588" height="920" />
-<p class="pcap"><b>Jean-Baptiste de Lamarck</b>,
-1744-1829, a French physician
-and ex-military man, founded
-the modern study of animals
-without backbones and coined
-the term invertebrates to describe
-them as a group. When
-his battle wounds forced him
-to take up a new career, he
-studied botany and published
-a study of French plants. He
-later turned to invertebrates,
-and between 1815 and 1822
-published the classic <span class="noti">Histoire
-naturelle des animaux sans
-vert&egrave;bres</span>. He applied his vast
-knowledge of living invertebrates
-to paleontological work,
-greatly enhancing the knowledge
-of fossil invertebrates.
-Lamarck was also an evolutionary
-theorist, and he believed
-that a single characteristic
-acquired by an animal
-during its lifetime could be
-passed on to its descendants
-by heredity (modern genetic
-theory was unknown at that
-time). He saw that evolution
-must have taken a long time to
-occur, and he supported the
-principle which has since become
-known as uniformitarianism.</p>
-</div>
-<div class="img" id="fig26">
-<img src="images/i16b.jpg" alt="" width="388" height="600" />
-<p class="pcap"><b>Georges Cuvier</b>, 1769-1832,
-was a French anatomist and
-paleontologist who specialized
-in the study of animals with
-backbones, the vertebrates. He
-had a long and brilliant career
-as a professor, eventually becoming
-France&rsquo;s minister of
-the interior in 1832. His skill
-as a comparative anatomist
-enabled him to understand
-how vertebrate fossils should
-be reconstructed to form a
-complete skeleton, and he was
-one of the first to use the small
-muscle scars on fossil bones to
-reconstruct the extinct animal&rsquo;s
-musculature. His classic work
-<span class="noti">R&eacute;cherches sur les Ossemens
-Fossiles de Quadrup&egrave;ds</span> was
-published in 1812. He is
-known for his theory of a series
-of natural catastrophes,
-each supposedly obliterating
-all extant life, to account for
-the great variety of ancient
-fossils. This theory was later
-supplanted by the theory of
-continuous evolution supported
-by Darwin, Lyell, and
-others.</p>
-</div>
-<div class="pb" id="Page_44">44</div>
-<div class="img" id="fig27">
-<img src="images/i17.jpg" alt="" width="520" height="800" />
-<p class="pcap"><b>Charles Darwin</b>, 1809-1882, is
-today a household name that
-is still invoked in controversy
-as it was more than a hundred
-years ago. An extraordinarily
-patient and insightful biologist,
-Darwin contributed the idea of
-natural selection, the &ldquo;weeding
-out&rdquo; of unfit individuals and
-species, and described it as the
-guiding principle of the evolution
-of life on this planet. His
-book <span class="noti">On the Origin of Species
-by Means of Natural Selection</span>,
-published in 1859, is
-the most important landmark
-in evolutionary studies. This
-was the culmination of decades
-of work, leading to conclusions
-startlingly similar to
-those of his fellow Englishman,
-Alfred Wallace. Darwin
-knew nothing of the genetic
-principle of biological heredity
-and variation, which has now
-assumed equal importance
-with natural selection in the
-study of the evolution of life.
-For paleontologists, Darwin&rsquo;s
-work meant they must look
-for transitional forms of life
-and not content themselves
-with Cuvier&rsquo;s assumptions that
-past life forms had been static
-and unchanging. During his
-travels in South America,
-Darwin contracted a disease,
-now known as Chagas&rsquo; disease,
-and suffered intense pain
-and discomfort the rest of his
-life. He died of a heart attack
-on April 19, 1882, and was
-buried in Westminster Abbey
-in London a few days later.</p>
-</div>
-<div class="pb" id="Page_45">45</div>
-<div class="img" id="fig28">
-<img src="images/i17a.jpg" alt="" width="388" height="600" />
-<p class="pcap"><b>Charles Lyell</b>, 1797-1875, revolutionized
-the study of geology
-partly by publicizing the
-earlier work of James Hutton,
-who died the year Lyell was
-born in Scotland, and partly
-by infusing the science with his
-own highly disciplined point
-of view. His greatest contribution
-was the firm establishment
-of Hutton&rsquo;s principle of uniformitarianism,
-or uniformism,
-which became the foundation
-for all modern
-geological work. Put simply,
-this is the principle that the
-processes we see operating to
-form and shape the Earth today
-have always operated in
-the past. Once this is admitted,
-it becomes clear that past geological
-time is vast, not short,
-a truly stunning notion for
-Lyell&rsquo;s time but a commonplace
-fact today. The first volume
-of his <span class="noti">Principles of Geology</span>
-was published in 1830; in
-his later works he championed
-Darwin&rsquo;s own revolutionary
-point of view, adding his own
-powerful arguments in support
-of the idea of natural selection.</p>
-</div>
-<div class="img" id="fig29">
-<img src="images/i17b.jpg" alt="" width="386" height="600" />
-<p class="pcap"><b>Alfred Wallace</b>, 1823-1913,
-was the co-originator, with
-Darwin, of the principle of
-natural selection, or &ldquo;survival
-of the fittest.&rdquo; The main difference
-between the two was
-that Wallace did not believe
-that natural selection explained
-things as well as Darwin
-thought it did, which has been
-borne out to a large extent by
-modern studies of genetic variation.
-Wallace worked in
-South America, along the Amazon
-and Rio Negro rivers,
-and in East Asia. He showed
-that the animals on either side
-of a line between Borneo and
-the Celebes Islands are radically
-different in their makeup
-and origin. Now known as
-&ldquo;Wallace&rsquo;s Line,&rdquo; his work
-has been vindicated by additional
-modern studies. Although
-Wallace did not become
-as well known as
-Darwin, his brilliant, independent
-studies lent a great
-deal of weight to the Darwinian
-view of evolution.</p>
-</div>
-</blockquote>
-<div class="interlude">&nbsp;</div>
-<div class="pb" id="Page_46">46</div>
-<div class="img" id="fig30">
-<img src="images/i18.jpg" alt="" width="800" height="775" />
-<p class="pcap"><span class="noti">The largest divisions of geologic
-time are eras, shown
-above in chronological order
-from the oldest on the bottom
-to the most recent on top.
-The scale at left shows the
-relative duration of each era.
-As the chart shows, geologists
-further divide time into periods
-and, in the Cenozoic
-Era, into epochs. The fossilization
-of animals in the Agate
-Springs area of Nebraska took
-place in the Miocene Epoch.
-Adjustments to this time
-chart are made as new data
-becomes available, so it
-should not be thought of as
-an unchanging reference. This
-diagram is adapted from one
-in The Emergence of Man series
-published by Time-Life
-Books.</span></p>
-</div>
-<table class="center" summary="">
-<tr class="th"><th colspan="4">Geologic Time Chart</th></tr>
-<tr class="th"><th> </th><th>Period </th><th>Epoch </th><th>Time span (years before present)</th></tr>
-<tr><td class="l">Cenozoic </td><td class="l">Quaternary </td><td class="l">Pleistocene </td><td class="r">10,000 to 2 million</td></tr>
-<tr><td class="l"> </td><td class="l">Tertiary </td><td class="l">Pliocene </td><td class="r">2 to 5 million</td></tr>
-<tr><td class="l"> </td><td class="l"> </td><td class="l"><b>Miocene</b> </td><td class="r"><b>5 to 23 million</b></td></tr>
-<tr><td class="l"> </td><td class="l"> </td><td class="l">Oligocene </td><td class="r">23 to 34 million</td></tr>
-<tr><td class="l"> </td><td class="l"> </td><td class="l">Eocene </td><td class="r">34 to 55 million</td></tr>
-<tr><td class="l"> </td><td class="l"> </td><td class="l">Paleocene </td><td class="r">55 to 65 million</td></tr>
-<tr><td class="l">Mesozoic </td><td class="l">Cretaceous </td><td class="l"> </td><td class="r">65 to 138 million</td></tr>
-<tr><td class="l"> </td><td class="l">Jurassic </td><td class="l"> </td><td class="r">138 to 205 million</td></tr>
-<tr><td class="l"> </td><td class="l">Triassic </td><td class="l"> </td><td class="r">205 to 240 million</td></tr>
-<tr><td class="l">Paleozoic </td><td class="l">Permian </td><td class="l"> </td><td class="r">240 to 290 million</td></tr>
-<tr><td class="l"> </td><td class="l">Carboniferous </td><td class="l"> </td><td class="r">290 to 365 million</td></tr>
-<tr><td class="l"> </td><td class="l">Devonian </td><td class="l"> </td><td class="r">365 to 410 million</td></tr>
-<tr><td class="l"> </td><td class="l">Silurian </td><td class="l"> </td><td class="r">410 to 435 million</td></tr>
-<tr><td class="l"> </td><td class="l">Ordovician </td><td class="l"> </td><td class="r">435 to 500 million</td></tr>
-<tr><td class="l"> </td><td class="l">Cambrian </td><td class="l"> </td><td class="r">500 to 570 million</td></tr>
-<tr><td class="l">Precambrian </td><td class="l"> </td><td class="l"> </td><td class="r">570 to 4,500+ million</td></tr>
-</table>
-<div class="pb" id="Page_47">47</div>
-<h3 id="c6">The Geologic History of Agate</h3>
-<p>Although the whole story of Agate Fossil Beds dates
-from the formation of the Earth four and one half
-billion years ago, only the last 600 million years is
-known in detail. It was about 600 million years ago
-that many plants and animals began to have hard
-parts&mdash;parts likely to be preserved as fossils. The
-few fossils contained in older rocks are often folded,
-twisted, squeezed, and distorted so that their original
-character is all but erased. That isn&rsquo;t always the case,
-of course. Some of these old rocks, the Belt Series
-in Montana, look as though they were deposited only
-a few million years ago; they contain traces of algal
-colonies indicative of the generally simple life forms
-on the primitive Earth. The old rocks, deposited
-during the first four billion years of Earth&rsquo;s history,
-record the Precambrian Eons, spanning eight-ninths
-of geologic time.</p>
-<p>The evolutionary development of skeletal remains
-has aided in the study of geologic history. The last
-600 million years have been divided into units for
-ease of discussion and comparison. The three largest
-divisions are the eras&mdash;Paleozoic (ancient life), Mesozoic
-(middle life), and Cenozoic (recent life). We
-are viewing all this from our vantage point at (what
-is now) the most recent episode of the Cenozoic.</p>
-<p>To begin at the known beginning, we only need
-go back to the start of the Paleozoic Era some 600
-million years ago. No Precambrian, Paleozoic, or
-Mesozoic rocks can be seen around Agate, but we
-know from rocks found in comparable areas about
-what to expect under the surface at Agate: thousands
-of meters of sedimentary rocks, most of them laid
-down in an ocean. During the Paleozoic and most
-of the Mesozoic eras, up until about 70 million years
-ago, the west-central United States was covered by
-seas. The area now occupied by the Rocky Mountains
-was then a long north-south trough in which
-thick sediments collected. To the east, the present
-Great Plains area was the floor of a shallower sea.
-Sediments collected in the trough and on the sea
-bottom. Gradually, over a period of 530 million
-years, the sediments accumulated to a thickness of
-over 2,100 meters (6,900 feet). A dynamic &ldquo;give-and-take&rdquo;
-<span class="pb" id="Page_48">48</span>
-process, this sedimentation was the result of
-periods when the sea rose and fell several times.</p>
-<p>If the Paleozoic sounds a little dull, it&rsquo;s because
-we haven&rsquo;t told the whole story. During the Paleozoic
-Era, all the major groups of organisms evolved.
-The seas swarmed with trilobites and shellfish of all
-kinds, some weird and fantastic and some very like
-those alive today. With them coexisted fish and sea-lilies,
-seaweeds and giant swimming &ldquo;scorpions.&rdquo;
-For the first time, plants and then animals came out
-of the sea to live on the land. These events and
-creatures are preserved in Paleozoic rocks. The Mesozoic
-Era saw the development of mammals from
-reptiles, the rule of giant dinosaurs, and the beginnings
-of flight. Strange reptiles evolved and returned
-to the sea, or glided through the air on motionless
-wings. The Sundance Formation, deposited in the
-northern Rocky Mountains about the middle of the
-Mesozoic Era, is noted for the masses of bullet-shaped
-squid shells found in it. Water, land, and air
-were full of life.</p>
-<p>In the Middle Mesozoic, the trough drained and
-much of it became an area of swamp and tropical
-forest extending from Montana to southern Utah.
-This was the domain of our largest dinosaurs, giant
-reptiles whose bones were preserved in impressive
-numbers. Como Bluff and Bone Cabin, Wyoming;
-Morrison, Colorado; and Dinosaur National Monument
-and Cleveland, Utah, are the sites of quarries
-where many fine specimens of <i>Apatosaurus</i>, <i>Diplodocus</i>,
-<i>Stegosaurus</i>, and <i>Allosaurus</i> have been collected.
-These caches of bones have made our large
-museums showplaces known throughout the world.</p>
-<p>During the last 65 million years of the Mesozoic,
-the trough fluctuated up and down. During much of
-that time a broad, shallow sea covered central North
-America from the Gulf of Mexico to the Arctic
-Ocean. The sea was filled with fish like the giant
-<i>Portheus</i> (3.5 meters/11.5 feet long), with squid-like
-animals floating about in elaborate chambered shells,
-and with reptiles which had gone back to the water.
-Where there was a broad coastal plain, it swarmed
-with dinosaurs, the ones that make Lance Creek,
-Wyoming and Hell Creek, Montana famous collecting
-grounds for museum field parties. Yet at the end
-of the era the trough was a seaway again, and in the
-Agate area a final blanket of black mud, the Pierre
-<span class="pb" id="Page_49">49</span>
-Shale, was deposited in the sea.</p>
-<p>At the end of the Mesozoic Era a profound change
-came over the land. The trough, with hundreds of
-meters of sediments accumulated on its bottom, was
-drained and folded by pressures built up in the
-Earth&rsquo;s crust. To the south, the Colorado Plateau
-rose slowly and smoothly; to the north folding and
-faulting built complex mountain ranges. This uplift
-is called the Laramide Revolution because of the
-magnitude of the change it made on the face of the
-continent.</p>
-<p>At the beginning of the Cenozoic Era, about 65
-million years ago, the Rockies and the Great Plains
-were slowly rising. Rains fell and rivers carried the
-water, wearing away the old sediments. Some sediments
-were carried west into the Pacific Ocean, or
-deposited on the land and covered over by new sediments.
-Some sediments remained within the Rockies,
-settling into basins during the early Cenozoic.
-Other sediments were carried east by the rivers, beyond
-the Great Plains and into the Mississippi Embayment.
-Mountain building and erosion tended to
-cancel out one another in the Rockies, preventing
-the mountains from reaching great heights. The
-mountain bases were perhaps no more than 300
-meters (1,000 feet) above sea level, and the crests
-perhaps 600 meters (2,000 feet) above that.</p>
-<p>Before long, the basins within the Rockies filled
-with sediments. The basins overflowed, and at last
-sediments began to cover the Great Plains. This was
-near the end of the Eocene Epoch, about 35 million
-years ago. Subtropical rivers, flowing sluggishly,
-rolled out over their banks and left their loads of silt
-and clay on the featureless plain.</p>
-<p>The oldest part of the blanket of sediments, the
-White River Beds, extended from Saskatchewan to
-Texas. Nearly 200 meters (650 feet) of muds, clays,
-silts, and river gravels were laid down during the 11
-million years of the Late Eocene and Oligocene
-Epochs. Magnificent exposures of these beds can be
-seen at Scotts Bluff National Monument in the
-valley of the North Platte, in Toadstool Park north
-of Crawford, Nebraska, and particularly in the Big
-Badlands of southwestern South Dakota.</p>
-<p>The kind of floodplain deposition characteristic of
-the Oligocene on the Great Plains ended about the
-beginning of the next epoch, the Miocene. In Nebraska
-<span class="pb" id="Page_50">50</span>
-the process continued, but eventually erosion
-began wearing away the accumulated sediments. The
-land to the west was uplifted a little, and the streams
-flowed off the high ground fast enough to cut down
-into what they had just deposited. On this eroded
-surface, the layers of tan silts, fine sands, and clays
-known as the Gering Formation were deposited.</p>
-<p>On top of the Gering Formation, in the Late Oligocene,
-is the Monroe Creek Formation, the oldest
-formation actually exposed in the Agate area. This
-formation is named for exposures in Monroe Creek
-Canyon north of Harrison, Nebraska, and may be up
-to 75 meters (245 feet) thick. You can see a little of
-the Monroe Creek Formation&rsquo;s pinkish silts and
-volcanic glass shards exposed in the valley of the
-Niobrara River. Where it is more exposed by erosion
-than at Agate, the Monroe Creek Formation forms
-magnificent cliffs along the Pine Ridge and similar
-areas of high ground. The best local examples are at
-Fort Robinson State Park between Harrison and
-Crawford, Nebraska. A close look can be obtained in
-Smiley Canyon just west of the fort, where old U.S.
-Highway 20 is maintained as a scenic drive.</p>
-<p>After the Monroe Creek interval, near the end of
-the Oligocene, deposition of the famous Agate
-Fossil Beds began. Geologists have named this
-sequence of grayish silts and sands the Harrison
-Formation for its occurrence near Harrison,
-Nebraska. A short interval of erosion separates it in
-some areas from the Monroe Creek Formation
-below, and its coarser sands indicate increasing
-uplift of lands to the west. Wind played a smaller
-role in deposition than in Monroe Creek times,
-though that is certainly not true at the <i>Stenomylus</i>
-quarry. The Harrison Formation was the last of the
-truly widespread deposits seen in the Miocene of
-the Great Plains. Many rivers flowing eastward from
-the Rockies contributed sands to Wyoming, South
-Dakota, and Nebraska.</p>
-<p>Generally the Harrison Formation and the overlying
-Marsland Formation are only moderately fossiliferous,
-but along the Niobrara River here at Agate,
-Nebraska, the accumulation of rhinoceros and
-camel skeletons is one of the wonders of the fossil
-world. Here, thousands of animals perished in two
-droughts which coincided with conditions perfect for
-preservation. About two kilometers (1.2 miles) east
-<span class="pb" id="Page_51">51</span>
-of the Monument headquarters the dried-out, mummified
-bodies of perhaps a hundred or more little
-camels, <i>Stenomylus hitchcocki</i>, were buried under
-windblown sand during the first drought.</p>
-<p>Shortly after the camels were buried there was a
-brief period of erosion and then the Marsland Formation
-began to be deposited. Named for a little
-village east of Agate, the Marsland Formation consists
-of basal river channel deposits followed by about
-45 meters (150 feet) of wind-blown tan-and-gray
-sands. It is in one of these river channel deposits that
-the Agate rhinoceros quarries are located.</p>
-<p>The second drought occurred early in Marsland
-times and literally hundreds of the little rhino,
-<i>Menoceras</i>, were preserved when their carcasses were
-broken up by a reborn river and buried like a mat of
-jackstraws in a river lake.</p>
-<p>After Marsland times there was more erosion, in
-some places by rushing streams that cut down 91
-meters (300 feet) through soft sediments, to the top
-of the Monroe Creek Formation. In these channels
-the Runningwater Formation was deposited because
-it filled in the stream valleys and wound around the
-high spots. This channel deposit is not found everywhere,
-but it does have an equivalent in southwestern
-South Dakota. Other deposits of similar age are
-found in many parts of the Great Plains, and they
-contain fossil animals like those found in the Runningwater
-Formation.</p>
-<p>The turbulent streams which deposited the Runningwater
-Formation were flowing off newly uplifted
-land to the west. This was the beginning of the most
-recent major uplift of the Rocky Mountains, and it
-signalled a great change in the pattern of deposition
-on the Great Plains. No longer would broad blankets
-of sediments be deposited by sluggish streams originating
-in the low, broad warp of the Rockies.</p>
-<p>This latest uplift is called the Rocky Mountain
-Revolution. It brought on a period of alternating
-cycles of deep channel cutting and stream deposition.
-Floodplain deposits were restricted to narrow ribbons
-in river-cut valleys. Even more important than
-the changes in deposition was the effect of this uplift
-on the climate. As the Rockies began to rise to their
-present height, the climate became increasingly arid
-and the tree-dotted savanna of the old Great Plains
-gave way to grasslands.</p>
-<div class="pb" id="Page_52">52</div>
-<p>Several kilometers south of Agate, the Sheep
-Creek Formation was laid down during the Middle
-and Late Miocene. The appearance of the grazing
-horse <i>Merychippus</i> in these channel and floodplain
-deposits marked the establishment of the grasslands
-as the newly dominant ecosystem of the Great Plains.
-At that time the &ldquo;modern&rdquo; fauna began to replace
-the old, and new patterns of life were established.</p>
-<p>Again rejuvenation of the stream system, probably
-reflecting further uplift in the west, started another
-erosional interval that began to wash away the
-beds just deposited. When deposition followed in
-the Late Miocene, a new series of channel and floodplain
-deposits, the Lower Snake Creek Beds, was
-laid down. On them was deposited the Upper Snake
-Creek Beds, and together they span most of the Late
-Miocene and the Early and Middle Pliocene epochs.
-Harold Cook collaborated with W. D. Matthew of
-the American Museum of Natural History, publishing
-important papers on the numerous finds from
-these fossiliferous deposits. Animals new to science
-are still being discovered in the Snake Creek Beds.</p>
-<p>After Snake Creek times, the area immediately
-around Agate was left out of the mainstream of
-events on the Great Plains. The continuing uplifts
-of the Rocky Mountains were no longer recorded
-here in cycles of downcutting and channel deposition.
-If the cycles continued here, all traces have
-now been washed away&mdash;an unlikely possibility. The
-view from the high plains above the valley of the
-Niobrara River reveals only the rolling surface of
-the pre-Runningwater deposits.</p>
-<p>A more complete record is found in the river terraces
-of major streams, the North Platte to the south
-and the White and Cheyenne Rivers to the north.
-These terraces tell the story of continuing uplifts. To
-the south, east, and northeast of the Platte the record
-is also written in fossil bones, but these are outside
-the scope of our story.</p>
-<p>Northwestern Nebraska, northeastern Colorado,
-southeastern Wyoming, and southwestern South Dakota
-today remain a promised land for paleontologists
-studying mammal life in North America during the
-middle and later Cenozoic Era. The fossil deposits in
-the Agate area are surpassed in importance only by
-the Late Eocene and Oligocene deposits of the Big
-Badlands and Pine Ridge in South Dakota.</p>
-<div class="pb" id="Page_53">53</div>
-<h3 id="c7">Ecology: Change and Adaptation</h3>
-<p>During the Age of Mammals (the Tertiary Period),
-three major environments dominated western Nebraska.
-The first of these occurred during the Paleocene,
-Eocene, and Oligocene epochs. This was
-a forest system where trees were the major component
-of the flora. Meadows were found only in
-scattered areas and can be considered a minor element.
-There is no geologic or paleontologic record
-of the Paleocene and Eocene in the Agate area, but
-when our present knowledge of the early Tertiary
-Rocky Mountain floras is projected eastward a bit,
-a predominantly forested landscape is indicated.</p>
-<p>It is in some ways ironic that while the Oligocene
-land-laid sediments of southwestern South Dakota,
-western Nebraska, southeastern Wyoming, and
-northeastern Colorado contain one of the best vertebrate
-fossil records in the world, the plant record
-is almost non-existent. Unfortunately the groundwater
-chemistry that was so right for the preservation
-of bones was hostile to the preservation of plants.
-Hackberries (<i>Celtis</i>) and walnuts (<i>Juglans</i>) are the
-only recorded plant species from the Oligocene in
-this very large area. Because these are such widespread
-and climatically tolerant types, they tell us
-almost nothing about the environment. Indications
-of the flora at Agate may be obtained, however,
-from the extraordinary Late Eocene flora found at
-Florissant, Colorado, south of Denver. Although this
-deposit does contain some upland species, it generally
-indicates a warm temperate forest including
-such things as horsetail rushes, ferns, cattails,
-grasses and sedges, poplar, willow, birch, oak, elm,
-serviceberry, sycamore, maple, sumac, and&mdash;of
-course&mdash;hackberries and walnuts.</p>
-<p>During the Early Miocene, slightly changed
-climatic conditions brought about by minor uplifts
-in the Rocky Mountain area transformed the
-immediate area of western Nebraska into a savanna
-of mixed trees and grasslands. This second system
-probably reached its climax just about the time the
-Harrison Formation was being laid down during the
-Early Miocene. This was a savanna with scattered
-clumps of trees, gallery forests, and grasslands. The
-modern world&rsquo;s richest and most diverse fauna of
-hoofed mammals can be found on the savannas of
-east Africa. On the savannas, grazing and browsing
-(grass eating and leaf eating) adaptations of the
-larger plant eaters are represented.</p>
-<div class="pb" id="Page_54">54</div>
-<div class="img" id="fig31">
-<img src="images/i19.jpg" alt="" width="1000" height="721" />
-<p class="pcap"><a href="#fig34">35 million years ago</a></p>
-</div>
-<div class="pb" id="Page_56">56</div>
-<div class="img" id="fig32">
-<img src="images/i20.jpg" alt="" width="1000" height="722" />
-<p class="pcap"><a href="#fig35">25 million years ago</a></p>
-</div>
-<div class="pb" id="Page_58">58</div>
-<div class="img" id="fig33">
-<img src="images/i21.jpg" alt="" width="1000" height="718" />
-<p class="pcap"><a href="#fig36">15 million years ago</a></p>
-</div>
-<div class="pb" id="Page_60">60</div>
-<div class="img" id="fig34">
-<img src="images/i22.jpg" alt="" width="800" height="578" />
-<p class="pcap"><a href="#fig31">35 million years ago</a>, life
-along the Niobrara River near
-Agate would have appeared
-something like this. Two oreodons
-(1) have startled an alligator
-(2) and two hippopotamus-like
-<span class="noti">Aepinacodons</span> (3)
-along the river bank. Climbing
-a tree is an opossum (4), one
-of the oldest forms of life in
-the world today. Note the
-many familiar trees and
-plants, particularly the cottonwood,
-willow, beech, dogwood,
-and cattail.</p>
-</div>
-<div class="img" id="fig35">
-<img src="images/i22a.jpg" alt="" width="800" height="574" />
-<p class="pcap"><a href="#fig32">25 million years ago</a>, a savanna
-dominates the Agate
-landscape. Copses of oak and
-pine are interspersed with
-open grassland. In the foreground
-are several <span class="noti">Parahippus</span>
-(1), an ancestor of today&rsquo;s
-horse, while <span class="noti">Oxydactylus</span> camelids
-(2) move away into the
-distance and, overhead, a
-hawk (3) searches for rodents.</p>
-</div>
-<div class="img" id="fig36">
-<img src="images/i22b.jpg" alt="" width="796" height="577" />
-<p class="pcap"><a href="#fig33">15 million years ago</a>, the Agate
-landscape has changed to
-an open prairie. A small herd
-of <span class="noti">Merychippus</span> horses (1)
-races toward the arroyo in the
-distance, narrowly escaping
-ambush by a large, leopard-like
-cat known as <span class="noti">Pseudaelurus</span>
-(2). A few cottonwoods,
-elms, sycamores, and willows
-grow along the river, but cedars
-predominate in the arroyo
-in the middle ground,
-where they are protected from
-winds that sweep across the
-plains. Though the animals
-have changed, the landscape is
-essentially like this today.</p>
-</div>
-<div class="pb" id="Page_61">61</div>
-<p>In western Nebraska the savanna environment
-lasted for only a very short time, in a geologic sense,
-before it gave way to a wave of advancing grasslands,
-the third phase of Tertiary environment in the area.
-Tallgrass prairie such as that still found 325 kilometers
-(200 miles) east of Agate a century ago must
-have been first among the grassland types. Trees,
-when present at all, were restricted to the borders
-of streams. Then as the climate became even more
-arid the prairie or tall grass retreated eastward, while
-the forest moved before it even farther to the east
-and south, and the modern shortgrass of the plains
-took its place. Today Agate lies in one of the valleys
-whose rivers are slowly dissecting the High Plains.</p>
-<p>The modern plains are dominated by short, curly,
-sodforming buffalo grass, a plant well adapted to the
-area&rsquo;s light rainfall, periodic droughts, low humidity,
-rapid evaporation, and high winds. The dominant
-vertebrate animals are burrowers and grazers, and
-dogs are the primary carnivores. Hoofed animals
-such as the pronghorn, the ultimate in the running
-and bounding adaptation; jumpers and hoppers,
-such as jackrabbits and jumping mice and rats; and
-burrowing mound builders, such as the prairie dog
-(a large ground squirrel), the pocket gopher, and
-harvester ants typify the major occupations of plains
-animals.</p>
-<p>The environmental type seen on the Great Plains
-of North America is elsewhere best developed in the
-Pampas of Argentina, the Puztas of Hungary, the
-Veld of Africa, and the Steppes of Russia. In the
-climatic classification of the climatologist and geographer,
-the term <i>steppe climate</i> is applied to all these
-areas, the Great Plains included.</p>
-<p>If the savanna is the halfway station between forests
-and grasslands, then the fossil fauna of the Early
-Miocene at Agate was a fauna in the beginning of
-a serious transition. In the vicinity of Agate, the
-fauna from the Late Oligocene was dominated by
-mammals with low-crowned teeth. The crown is that
-part of the tooth which is above the roots and exposed
-beyond the gums. Among the herbivores, the
-<span class="pb" id="Page_62">62</span>
-browsers can live a long life with low-crowned teeth.
-But when any appreciable amount of grass, particularly
-the short, tough grass of the plains and the
-abrasive dirt and sand that accompanies it, becomes
-part of an herbivore&rsquo;s diet, there is a great increase
-in the rate of tooth wear. Teeth which have evolved
-for browsing quickly wear down to the gums and the
-individual dies of starvation.</p>
-<p>Accompanying the development of extensive
-grasslands came the evolution of the high-crowned
-tooth. This process begins simply with the growth
-of a taller crown that erupts completely from the
-gum right after the milk or deciduous teeth fall out.
-Another step is the development of a longer or
-higher crown most of which is held in the jaw and
-then slowly pushed out as the chewing surface is
-worn down. This is the &ldquo;mechanical pencil&rdquo; effect
-in that the &ldquo;lead&rdquo; may be pushed out as needed.
-Teeth of this type are perhaps best seen in the later
-horses. From their appearance in the Late Paleocene
-until the end of the Early Miocene, all horses had
-low-crowned teeth. With these they could chew the
-soft leaves and twigs of trees and shrubs, first in the
-forests and later in the groves and clumps on the
-developing savanna. By Early Miocene (i.e., Harrison)
-times, there was only a slight increase in crown
-height in <i>Parahippus</i>, but it had evolved an increasingly
-complicated crown pattern which served to
-lengthen the time it took for the tooth surface to
-wear down flat. With the greater aridity of the changing
-climate, the teeth of <i>Parahippus</i> became higher
-and higher crowned, as the individuals with the best
-teeth lived longest and had greater opportunity to
-produce offspring than those with lower-crowned
-teeth. In some species, the tooth material called cement,
-which ordinarily covers the roots of the teeth,
-began also to cover the enamel of the crown and
-give additional wearing strength to the teeth. Soon
-after the beginning of the Middle Miocene, two species
-had developed cement-covered teeth whose
-crowns were high enough to warrant placing them
-into two new genera of horses, <i>Merychippus</i> and
-<i>Protohippus</i>. These forms, first recognized in the
-Lower Sheep Creek Beds in the Agate area, were
-the first horses to use the mechanical-pencil effect,
-having cheek teeth that continued to rise out of the
-jaw as the tooth was worn down. <i>Merychippus</i> later
-<span class="pb" id="Page_63">63</span>
-gave rise to a line of three-toed horses, which lived
-on into the Pliocene; <i>Protohippus</i> gave rise to a line
-which ultimately led to <i>Equus</i>, the modern horse.</p>
-<p>The ultimate in high-crowned teeth occurs when
-roots do not ever form at the base of the tooth;
-additional crown material is constantly added at the
-bottom of the tooth as it is pushed out of the gum.
-This type of growth resembles the foundry process
-of extrusion, where metal or plastic is pushed
-through a mold to produce a continuous strand. This
-extreme development is seen in the incisors or gnawing
-teeth of beavers, gophers, and other Late
-Oligocene rodents, and in the grinding teeth of only
-a few forms. The cheek teeth (the grinders) of modern
-pronghorns (artiodactyls), gophers (rodents), and
-rabbits (lagomorphs) are typical of this kind of
-development today. During the Middle Oligocene,
-only the strange little fox terrier-sized, flat-headed
-oreodon <i>Leptauchenia</i>, the tiny &ldquo;deer&rdquo; <i>Hypisodus</i>,
-and the rabbit <i>Palaeolagus</i> had mechanical pencil-type
-teeth. Some of the rhinos then had fairly tall
-crowns, but these don&rsquo;t really qualify as high-crowned
-teeth. It was not until later on, when the
-grasslands took over completely, that high-crowned
-teeth really came into their own.</p>
-<p>There was no dramatic change in the fauna at the
-beginning of the Miocene, and many Oligocene genera
-carried over into the new epoch. Most of the
-Eocene hold-overs, primitive animals that had survived
-in the extensive forests, became extinct when
-the forests began to retreat; but for the most part
-the record continued undisturbed. This is to be expected
-where the deposition of sediments continues
-without interruption. (Remember that the epochs,
-periods, and eras were originally based on breaks in
-the European sedimentary record reflecting local
-events which would not necessarily show up in North
-America&rsquo;s sediments.)</p>
-<p>By the time the Harrison Formation was deposited,
-the development of the halfway world of the
-savanna was beginning to affect the fauna. Although
-the Oligocene and the very earliest Miocene mammal
-faunas were highly varied and rich in types of
-animals, much of this was due to the continued presence
-of primitive and archaic forms, and to the explosive
-development of rhinos and oreodons. With
-the savanna becoming the dominant landscape, the
-shift to grazing and away from browsing became evident.
-Or, at least, the presence of animals that both
-browsed and grazed was indicative of changing
-times. As was mentioned earlier, grazing and burrowing
-are characteristics of plains herbivores. In
-such a transitional period we would expect to find
-an increase in burrowers and grazers as grasslands
-became more common.</p>
-<div class="pb" id="Page_64">64</div>
-<h3 class="interlude">Evolutionary Change</h3>
-<blockquote>
-<p>Animal species respond to environmental
-changes in a variety
-of ways. Simply put, some
-species die off, some adapt
-physically, and some move to
-a different habitat. On the
-next few pages are examples
-showing how three species responded
-to long-term environmental
-changes in the area
-around Agate Fossil Beds.
-The <i>Stenomylus</i> line died off;
-<i>Miohippus&rsquo;</i> evolutionary line
-remained a grazing animal but
-changed physically over the
-years, eventually becoming
-the modern horse; and the
-<i>Palaeocastor</i> line moved from
-land to water, gradually
-evolving into the beaver.</p>
-<p>Each of these three animals is
-portrayed here with partial
-skeleton, musculature, and
-outer skin to help you see its
-general composition and to
-emphasize certain physical
-features that developed in the
-species over time. Paleontologists,
-of course, work this
-way. From fragments and
-bones they reconstruct full
-skeletons, and from surmises
-about muscular structure,
-often based on present-day
-animals, they project the appearance
-of the animal. The
-artist, in this case Jay Matternes,
-then brings together
-these bits of evidence to give
-us a picture of life long ago.</p>
-<h4 id="ccc4">Stenomylus<br /><img class="icon" src="images/s_stenomylus.jpg" alt="Stenomylus" width="157" height="110" /></h4>
-<p>A small, gazelle-like camel similar to the present-day
-gerenuk of Africa. <i>Stenomylus</i> is the second most common
-animal found in the fossil beds at Agate. <i>Stenomylus</i>
-had hard hooves like modern antelopes and deer, unlike
-modern camels which have flesh-padded feet adapted to
-desert terrain. The three-hued coat is inferred from the coat
-of the modern gazelle, a similar form in adaptation.
-<i>Stenomylus&rsquo;</i> evolutionary line eventually died out in North
-America at the end of the Pleistocene. No one knows
-why both camels and horses died out on this continent.</p>
-<div class="pb" id="Page_65">65</div>
-<p><span class="lr"><span class="small">The distance between grid lines represents five centimeters.</span></span></p>
-<div class="img" id="fig37">
-<img src="images/i23.jpg" alt="" width="718" height="675" />
-<p class="pcap"><span class="ss">1</span> The ears moved in a parallel
-fashion, not independently; the parallel movement is inferred
-from modern llamoids, to
-which <span class="noti">Stenomylus</span> is related.</p>
-<p class="pcapc"><span class="ss">2</span> <span class="noti">Stenomylus&rsquo;</span> musculature was
-adapted for high-speed running,
-similar to the present-day
-pronghorn.</p>
-<p class="pcapc"><span class="ss">3</span> The back structure suggests
-that <span class="noti">Stenomylus</span> would have
-made short, choppy leaps, not
-the graceful, arcing leaps of a
-modern impala.</p>
-<p class="pcapc"><span class="ss">4</span> Limbs were long in proportion
-to the body, allowing the animal
-to run with great speed.</p>
-<p class="pcapc"><span class="ss">5</span> <span class="noti">Stenomylus</span> had a hard, chitinous
-hoof, an adaptation for
-greater running speed, and for
-sure footing on rough terrain.</p>
-</div>
-<div class="pb" id="Page_66">66</div>
-<h4 id="ccc5">Miohippus<br /><img class="icon" src="images/s_miohippus.jpg" alt="Miohippus" width="150" height="106" /></h4>
-<p>Over the last 60 million years the horses have evolved from
-small, terrier-sized animals to the diversity of size we know
-today, from the huge Clydesdales to the diminutive Shetland
-ponies. The three-toed early horse known as <i>Miohippus</i>
-was about the size of a sheep. The descendants of
-<i>Miohippus</i> apparently went in two directions in their evolution:
-One group continued to be forest-grazing, three-toed
-horses that eventually reached the size of modern horses but
-died out later. The other group, through such intermediate
-forms as <i>Parahippus</i>, became grassland forms that
-led eventually to the modern one-toed horses. Horses became
-extinct in North America at the end of the Pleistocene,
-but no one knows why. They continued to evolve on
-other continents and were re-introduced in historic times.</p>
-<div class="pb" id="Page_67">67</div>
-<p><span class="lr"><span class="small">The distance between grid lines represents five centimeters.</span></span></p>
-<div class="img" id="fig38">
-<img src="images/i24.jpg" alt="" width="887" height="607" />
-<p class="pcap"><span class="ss">1</span> The back was straighter and
-stiffer than in earlier horses,
-partly because of the increasing
-size of the animals and
-partly to allow sustained open-plains
-running.</p>
-<p class="pcapc"><span class="ss">2</span> Limbs were long in proportion
-to the body, an evolutionary
-trend in the horses for speed
-in open-plains running, rather
-than darting about in forests.</p>
-<p class="pcapc"><span class="ss">3</span> Most of the weight of the animal
-was on the middle toe, which has become a single toe
-in modern horses. This is an adaptation for endurance and
-stability in open grasslands.</p>
-<p class="pcapc"><span class="ss">4</span> The upright mane is a primitive
-horse characteristic; wild horses today have reverted to this trait.</p>
-<p class="pcapc"><span class="ss">5</span> The coat is shown as striped, a
-probable holdover from earlier horses that dwelled in forests,
-where a striped coat would provide camouflage.</p>
-<p class="pcapc"><span class="ss">6</span> A large, deep mandible supported
-teeth adapted to grazing and the grinding of grasses
-and other wild plants. The teeth were deep-rooted and
-continuously erupted as the surface was worn down by the
-grit and dirt that came with the large quantities of plant food
-consumed daily.</p>
-</div>
-<div class="pb" id="Page_68">68</div>
-<h4 id="ccc6">Palaeocastor<br /><img class="icon" src="images/s_palaeocastor.jpg" alt="Palaeocastor" width="133" height="47" /></h4>
-<p><i>Palaeocastor</i> was an ancient beaver whose mode of life
-was like that of a modern prairie dog&mdash;land-oriented instead
-of water-oriented. <i>Palaeocastor</i> was small, about 12
-centimeters (5 inches) high, and about 30 centimeters (12
-inches) long. Its fossilized spiral burrows, called <i>Daemonelix</i>,
-survive to tell us what its habitation was like, a feature
-unique to <i>Palaeocastor</i> among all the fossil beavers. The
-<i>Daemonelix</i> shown here dwarfs a member of Olaf A.
-Peterson&rsquo;s field crew from the Carnegie Museum. The bones
-of a <i>Palaeocastor</i> and one of its predators were found at
-the bottom of one such burrow, helping to prove that
-<i>Palaeocastor</i> was responsible for making these corkscrew
-holes in the ground.</p>
-<p><span class="lr"><span class="small">The distance between grid lines represents five centimeters.</span></span></p>
-<div class="img" id="fig39">
-<img src="images/i25.jpg" alt="" width="946" height="369" />
-<p class="pcap"><span class="ss">1</span> The powerful jaw and musculature
-allowed for grazing on grasses and other plants, as
-well as masticating. The teeth were deep-rooted and would
-continue to erupt as the surface was worn down.</p>
-<p class="pcapc"><span class="ss">2</span> The complex musculature supported
-the use of the forelimbs in burrowing. <i>Palaeocastor</i>
-had a collarbone or clavicle, like us, for greater agility in
-using the forelimbs.</p>
-<p class="pcapc"><span class="ss">3</span> The forelimbs were adapted to
-burrowing in the ground.</p>
-<p class="pcapc"><span class="ss">4</span> The tail is like that of a modern
-burrowing rodent, such as a muskrat, whereas the modern
-beaver has a different, very specialized tail.</p>
-</div>
-<div class="pb" id="Page_69">69</div>
-<div class="img">
-<img src="images/i25a.jpg" alt="Daemonelix" width="404" height="600" />
-</div>
-</blockquote>
-<div class="interlude">&nbsp;</div>
-<div class="pb" id="Page_70">70</div>
-<p>A grazing animal is fairly easy to recognize, but
-how can we recognize a burrower? Some have radically
-adapted limbs and claws. Obvious cases are
-the common garden mole and the armadillo. The
-mole has powerful attachments for the muscles of
-the upper arm on the humerus, a bone so flattened
-that its width has come to match its length. Moles
-also have long, broad digging claws. The armadillo,
-which is also a digger but not a burrower in the same
-way a mole or a gopher is, has large curved claws
-for digging. Moles did start to become quite common
-in the Late Oligocene, so we can assume that a good
-burrowing environment was present.</p>
-<p>Another group which became extraordinarily
-common in the Late Oligocene of western North
-America was that of the ancestral pocket gopher.
-Direct proof that this group actually burrowed does
-not exist, but the abundance of fossil gophers
-suggests that they might have lived underground in
-colonies.</p>
-<p>A real surprise at Agate is the number of beaver
-burrows. The famous <i>Daemonelix</i> or &ldquo;devil&rsquo;s corkscrew&rdquo;
-attests to the dense population of <i>Palaeocastor</i>.
-By that relatively advanced stage of beaver
-evolution, the animals might be expected to behave
-like the modern-day muskrat, perhaps digging dens
-along stream borders and spending some of their
-time in the water. The presence of skeletons in the
-spiral burrows, however, indicates that <i>Palaeocastor</i>
-was primarily a burrower, one which perhaps lived
-very much like our present-day prairie dog. Despite
-that, there is no apparent structural modification to
-indicate burrowing abilities.</p>
-<p>Changing environmental conditions were pushing
-<i>Palaeocastor</i> toward extinction in the Early Miocene.
-The disappearance of that ancient beaver, while not
-unusual, presents a problem for the careless observer
-who might assume that ancient animals behaved like
-their modern counterparts. The burrowing beavers
-<span class="pb" id="Page_71">71</span>
-of Miocene Agate certainly have no modern counterparts.</p>
-<p>While we can delineate in a general way the prehistoric
-life of Agate, we can&rsquo;t describe the past in
-any detail. Plants most directly reflect the effects of
-climate&mdash;and plant fossils are absent at Agate. As
-the base of the food chain, plants carry the influences
-of climate on to the plant-eating animals. From the
-numerous animal fossils found at Agate we have
-learned most of what is known about the environment
-of that time. Sediments tell a good part of the
-story, and floras from other localities help, but much
-of Agate&rsquo;s ancient ecology must be inferred from the
-bones.</p>
-<p>Today, standing on the porch of the visitor center
-or walking along the path to University and Carnegie
-Hills, visitors find themselves in the midst of the
-shortgrass prairie. Five distinctive plant communities
-share this prairie, coexisting in a dynamic relationship
-which depends upon local climate variations.</p>
-<p>Even to the untrained eye, it is evident that the
-basic short-grass pattern has been modified by the
-shape of the land and by the Niobrara River. In the
-stream valley, along the tributaries, and on shaded
-north-facing slopes, the shortgrass community is
-mixed with taller grasses. If a dry cycle began, the
-short grasses would take over the whole area by
-migrating downslope from the exposed prairies. Of
-interest is the fact that over-grazing by either domesticated
-or wild animals will have the same effect
-as a dry period in that taller grasses will be replaced
-by short ones.</p>
-<p>Let&rsquo;s examine the five communities present today
-so we can appreciate the complexity of relationships
-between living things and the earth upon which they
-depend.</p>
-<p>First, we can begin in the Niobrara River itself.
-The river&rsquo;s water-dwelling plant inhabitants include
-algae, which grow underwater.</p>
-<p>Between the river and the dry ground is a second
-community&mdash;the marsh&mdash;which is often more wet
-than dry. The marsh has its own characteristic plant
-association. Most familiar are the cattails, mints, and
-willows, but just as important ecologically are arrowleaf,
-rush sedge, marshweed and blue verbena.
-These are moisture-loving plants that thrive on being
-thoroughly soaked during the wet part of the year.</p>
-<div class="pb" id="Page_72">72</div>
-<p>Beyond the marsh on the valley floor is a third
-community. Here the water table (the top of the
-saturated soil and rock zone) is close enough to land
-surface that the plants can easily send their roots
-down into the saturated zone. Here, in what the
-plant ecologists call the &ldquo;sub-irrigated floor plain&rdquo;
-we find a mid-grass community. Eighty-five percent
-of the vegetation is slender wheatgrass. Its wheat-like
-heads may, under favorable conditions, grow to
-a height of one meter (three feet). At Agate it is
-seldom over knee high. Kentucky bluegrass takes
-care of another 10 percent of the plant population.
-Imported from Europe as a pasture grass in the
-1600&rsquo;s, it spread so rapidly that it often beat the settlers
-onto new land as they moved westward. The
-remaining five percent includes imported redtop and
-such native grasses as switchgrass, foxtail barley, little
-bluestem, prairie cordgrass, and inland saltgrass.
-Wildflowers such as Flodmon thistle, yarrow, heath
-aster, salsify, and blue-eyed grass complete the community.</p>
-<p>Moving farther away from the stream, we rise up
-onto terraces within the valley. These terraces represent
-levels where the stream paused in its downcutting
-and cut sideways for awhile. At a drier level,
-on deep, well-drained sandy soils, they support the
-fourth or mixed-grass community.</p>
-<p>No exotics have yet appeared in this plant community.
-The grasses include prairie sandreed, sand
-bluestem, blue grama, needle-and-thread grass, and
-Indian ricegrass. Wildflowers include the prominent
-phlox, penstemon, and lupine. Unwelcome (to man
-and his grazing animals) is <i>Astragalus</i>, the selenium-concentrating
-plant better known as loco weed. The
-brittle prickly pear and spiderwort cactus are found
-here too.</p>
-<p>At higher levels in the terrace community, slightly
-steeper slopes and shallower soils cause some change
-in this mixed-grass assemblage. Here the dominant
-grasses are little bluestem, threadleaf sedge, needle-and-thread
-grass, and blue grama. Lupine disappears,
-and common pricklypear becomes the only
-cactus. In this community is found the yucca, its
-flowers a beautiful soft yellow in season and its spiny
-leaves painful at any time of the year. Avoid this
-plant; yucca spines break off under the skin and soon
-cause irritating festers. The yucca moth, often seen
-<span class="pb" id="Page_73">73</span>
-flying around the yucca seed pods, lays eggs in the
-plant&rsquo;s lemon-sized fruits. Inside the fruit are long
-rows of flattened, wedge-shaped seeds. When the
-yucca moth eggs hatch into caterpillars, they eat their
-way through the seeds, killing them. On the other
-hand it is the yucca moth with its long tongue that
-is solely responsible for pollinating the yucca flower!
-If you find a yucca fruit in early summer, you can
-(elsewhere than in the park) slice through it and see
-the caterpillars at work.</p>
-<p>On the high bluffs and overgrazed terraces is the
-fifth community, the short grass. This community
-too can be divided into two slightly different parts.
-The bluffs support blue grama grass, needle-and-thread
-grass, and Sandberg blue grass. Flowers and
-shrubs include <i>Eriogonum</i>, brittle pricklypear cactus,
-pepperweed, penstemon, broom snakeweed,
-fringed sagewort, and yucca. The other part of this
-community, the overgrazed terraces, have threadleaf
-sedge, needle-and-thread grass, and blue grama.
-Except for the familiar penstemon, all the flowers
-are restricted to this community. Gronwell, menzania,
-and bee plant are indicators of overgrazing.</p>
-<p>Certain cyclical variations are characteristic of
-these plant communities. First, the shortgrass and
-mixed-grass areas ebb and flow with changing moisture
-conditions from year to year. Second, grass populations
-change with the seasons. Cool-season grasses
-(foxtail barley, Indian rice grass, Kentucky bluegrass,
-needle-and-thread grass, Sandberg blue grass,
-and slender wheatgrass) flourish during spring and
-fall. During the warm summer the blue grama, inland
-saltgrass, little bluestem, prairie cordgrass, prairie
-sandreed, and switchgrass predominate. This natural
-adaptation to seasonal conditions uses the
-greatest potential of the growing season and at the
-same time provides species that will flourish in both
-wet and dry cycles.</p>
-<p>After reading this last section, you might look back
-at the section on Early Miocene ecology. Comparison
-reveals that a great deal of information can be obtained
-by examining living plants. In contrast, the
-lack of fossil flora from the Early Miocene at Agate
-has resulted in a scarcity of ecological information
-from that early epoch. Scientists begin their reasoning
-by such comparisons; you can begin your own
-exploration of the past in the same way.</p>
-<div class="pb" id="Page_74">74</div>
-<h2 id="c8"><span class="small">3 <span class="hst">Guide and Adviser</span></span></h2>
-<div class="pb" id="Page_76">76</div>
-<div class="img" id="fig40">
-<img src="images/i26.jpg" alt="" width="671" height="999" />
-<p class="pcap">Ask a ranger for directions to the protected example of a
-Devil&rsquo;s Corkscrew, the fossilized burrow of a small, beaver-like
-animal called <span class="noti">Palaeocastor</span>. See pages <a class="pgref" href="#Page_68">68</a>-69 for
-more information about this interesting animal.</p>
-</div>
-<div class="pb" id="Page_77">77</div>
-<h3 class="interlude" id="c9">Visiting the Park</h3>
-<h3 id="c10">Contents of This Section</h3>
-<dl class="toc">
-<dt><a href="#c10">Visiting the Park</a> 77</dt>
-<dd class="jl"><a href="#ccc7">Location</a></dd>
-<dd class="jl"><a href="#ccc8">Area</a></dd>
-<dd class="jl"><a href="#ccc9">Climate</a></dd>
-<dd class="jl"><a href="#ccc10">When to Visit</a></dd>
-<dd class="jl"><a href="#ccc11">Visitor Center</a></dd>
-<dd class="jl"><a href="#ccc12">Activities</a></dd>
-<dd class="jl"><a href="#ccc13">Camping</a></dd>
-<dd class="jl"><a href="#ccc14">Nearby Accommodations</a></dd>
-<dd class="jl"><a href="#ccc15">Transportation</a></dd>
-<dd class="jl"><a href="#ccc16">Establishment Date</a></dd>
-<dd class="jl"><a href="#ccc17">Address</a></dd>
-<dd class="jl"><a href="#ccc18">Access</a></dd>
-<dt><a href="#c11">Protection</a> 80</dt>
-<dd class="jl"><a href="#ccc19">Park Regulations</a></dd>
-<dd class="jl"><a href="#ccc20">Safety Tips</a></dd>
-<dt><a href="#c12">Birding Along the Niobrara</a> 81</dt>
-<dd class="jl"><a href="#ccc21">Taking the Annual Count</a></dd>
-<dt><a href="#c13">Collections of Agate Springs Fossils</a> 86</dt>
-<dt><a href="#c14">NPS Areas With Fossil Exhibits</a> 88</dt>
-<dd class="jl"><a href="#ccc22">Badlands</a></dd>
-<dd class="jl"><a href="#ccc23">Dinosaur</a></dd>
-<dd class="jl"><a href="#ccc24">Florissant</a></dd>
-<dd class="jl"><a href="#ccc25">Fossil Butte</a></dd>
-<dd class="jl"><a href="#ccc26">Petrified Forest</a></dd>
-<dd class="jl"><a href="#ccc27">John Day</a></dd>
-<dd class="jl"><a href="#ccc28">Hagerman</a></dd>
-<dt><a href="#c15">Nearby National Parks</a> 90</dt>
-<dd class="jl"><a href="#ccc29">Badlands</a></dd>
-<dd class="jl"><a href="#ccc30">Devils Tower</a></dd>
-<dd class="jl"><a href="#ccc31">Fort Laramie</a></dd>
-<dd class="jl"><a href="#ccc32">Jewel Cave</a></dd>
-<dd class="jl"><a href="#ccc33">Mount Rushmore</a></dd>
-<dd class="jl"><a href="#ccc34">Scotts Bluff</a></dd>
-<dd class="jl"><a href="#ccc35">Wind Cave</a></dd>
-<dt><a href="#c16">Not So Nearby National Parks</a> 92</dt>
-<dd class="jl"><a href="#ccc36">Bighorn Canyon</a></dd>
-<dd class="jl"><a href="#ccc37">Little Bighorn</a></dd>
-<dd class="jl"><a href="#ccc38">Rocky Mountain</a></dd>
-<dd class="jl"><a href="#ccc39">Theodore Roosevelt</a></dd>
-<dt><a href="#c17">Armchair Explorations</a> 93</dt>
-</dl>
-<h4 id="ccc7">Location</h4>
-<p>Northwestern Nebraska 69
-kilometers (43 miles) north of Scottsbluff
-along the Niobrara River.</p>
-<h4 id="ccc8">Area</h4>
-<p>1,116 hectares (2,762 acres).</p>
-<h4 id="ccc9">Climate</h4>
-<p>Temperatures range from
-winter lows of -38&deg; C (-36&deg; F) to
-summer highs of 39&deg; C (101&deg; F). Winter
-temperatures average 1&deg; C (33&deg; F),
-and winter snow averages 60 centimeters
-(2 feet) for the whole winter.
-However, snowdrifts can be much
-higher. Summer nights are cool, with
-temperatures averaging 10&deg; C (50&deg; F).
-Average annual precipitation is 41 centimeters
-(16 inches), with most precipitation
-in April and May.</p>
-<h4 id="ccc10">When to Visit</h4>
-<p>Most people go to the
-park some time between June and August,
-but you can avoid the high summer
-temperatures by visiting in the
-spring, fall or&mdash;if you don&rsquo;t mind the
-cold and snow&mdash;in the winter. Spring
-can be blustery, but the fall is usually
-dry and the days are cool. Check ahead
-on local weather conditions if you plan
-a winter visit. Museums and tourist
-attractions in nearby Fort Robinson
-are open Memorial Day to Labor Day.</p>
-<h4 id="ccc11">Visitor Center</h4>
-<p>A ranger is on duty
-to help you and answer your questions.
-Fossil exhibits and part of James H.
-Cook&rsquo;s personal collection of Indian
-items are on display in the visitor center,
-and publications about the park,
-paleontology, and history are on sale.</p>
-<h4 id="ccc12">Activities</h4>
-<p>A trail from the visitor center
-takes you on a tour to both University
-and Carnegie Hills, with an interpretive
-display at each. The roundtrip
-distance is three kilometers (two miles)
-and takes about one hour. You may
-fish for German brown and rainbow
-trout in the Niobrara River if you have
-a Nebraska fishing license. The park
-has several tables for picnickers.</p>
-<div class="pb" id="Page_78">78</div>
-<h4 id="ccc13">Camping</h4>
-<p>The park has no camping
-facilities, but there are state campgrounds
-near Harrison and near Fort
-Robinson, Nebraska, and a commercial
-campground on Nebr. 26 between
-Mitchell and Scottsbluff, Nebraska.</p>
-<h4 id="ccc14">Nearby Accommodations</h4>
-<p>Hotels,
-motels, food stores, outdoor supply
-stores, and restaurants are available in
-Scottsbluff, Nebraska. A motel, restaurant,
-gas station, and grocery store
-are in Mitchell, Nebraska, 55 kilometers
-(34 miles) south of the park. There
-are a motel, food store, drugstore, and
-restaurant in Harrison, Nebraska, 37
-kilometers (23 miles) north of the
-park, and there are motels and restaurants
-at Fort Robinson, Nebraska, 37
-kilometers (23 miles) east of Harrison,
-or 74 kilometers (46 miles) northeast
-of the park.</p>
-<h4 id="ccc15">Transportation</h4>
-<p>Buses&mdash;The nearest
-bus connections are in Scottsbluff, Nebraska.
-Airport&mdash;Scottsbluff, Nebraska,
-has an airport served by a
-scheduled commercial airline. Rentals&mdash;Cars
-may be rented at the airport
-or at car rental agencies in Scottsbluff.</p>
-<h4 id="ccc16">Establishment of the park</h4>
-<p>June 5, 1965.</p>
-<h4 id="ccc17">Mailing Address</h4>
-<dl class="undent"><dt>Agate Fossil Beds</dt>
-<dt>National Monument, 301 River Road,</dt>
-<dt>Harrison, NE 69346.</dt></dl>
-<h4 id="ccc18">Access</h4>
-<div class="img" id="fig41">
-<img src="images/i27.jpg" alt="" width="600" height="369" />
-<p class="pcap">To reach the park from Scottsbluff,
-Nebraska, take Nebr. 26
-west to Mitchell, then Nebr. 29
-north to the park. From Fort
-Robinson, Nebraska, take
-Nebr. 20 west to Harrison,
-then Nebr. 29 south to the
-park.</p>
-</div>
-<div class="pb" id="Page_79">79</div>
-<div class="img" id="map1">
-<img src="images/map_lr.jpg" alt="" width="559" height="801" />
-<p class="center">Plains states<br /><a class="ab1" href="images/map_hr.jpg">High-resolution Map</a></p>
-</div>
-<div class="pb" id="Page_80">80</div>
-<h3 class="interlude" id="c11">Protection</h3>
-<div class="img" id="fig42">
-<img src="images/i28.jpg" alt="" width="613" height="600" />
-<p class="pcap">The trail from the visitor center takes you
-across the Niobrara River, up University Hill to
-the fossil layer, then to the fossil exhibit on
-Carnegie Hill, and back to the visitor center.
-The walk takes about one hour.</p>
-</div>
-<div class="img" id="fig43">
-<img src="images/i28a.jpg" alt="" width="607" height="600" />
-<p class="pcap">Two fishermen
-try their luck in the Niobrara.</p>
-</div>
-<h4 id="ccc19">Park Regulations</h4>
-<p>To ensure your
-safety and to protect the park&rsquo;s natural
-and historical resources, several regulations
-have been established by the
-National Park Service. Collecting of
-fossils, rocks, plants, or other objects
-is not permitted. Please be sure to
-leave everything as you find it along
-the trails and throughout the park for
-others to enjoy. If you have any questions
-about park regulations and policies,
-please ask the staff. The rangers
-are here to help you and to enforce the
-regulations.</p>
-<h4 id="ccc20">Safety Tips</h4>
-<p>Though snakes are not
-prevalent, be sure to watch for rattlesnakes
-as you walk about through the
-park, along the trails, and near the exhibits
-at Carnegie and University Hills.
-Avoid them if you see them, but do
-not harm them. As a general rule it is
-best to keep a good distance from any
-wildlife you see, not only to protect
-yourself and your children, but to
-avoid frightening or hurting the animal.
-It is best to observe wildlife at a
-safe distance with field glasses. While
-walking about the park, do not take
-chances by climbing on loose rock, or
-going into unauthorized areas, and do
-not let your children go beyond your
-control. Park your vehicle in authorized
-places and observe the normal
-rules of road safety and courtesy while
-you are in the park, and when entering
-and leaving it.</p>
-<div class="pb" id="Page_81">81</div>
-<h3 class="interlude" id="c12">Birding Along the Niobrara</h3>
-<h4 id="ccc21">Taking the Annual Count</h4>
-<p>One of the joys of visiting the national
-parks, author Freeman Tilden once
-said, is having an unexpected, provocative
-experience. You go to a park to
-see or do one thing, and you come
-across something else that strikes your
-fancy as well. Tilden called it serendipity.
-At Agate Fossil Beds National
-Monument, one such experience might
-be birdwatching. In this piece, Doris
-B. Gates writes of her annual bird surveys
-in this area.</p>
-<p class="tb">In western Nebraska the northern
-part of the Great Plains ends at the
-Pine Ridge, an escarpment circling
-from Wyoming across Nebraska&rsquo;s north
-edge and winding into South Dakota.
-A major grass of this mixed prairie is
-little bluestem, Nebraska&rsquo;s state grass,
-whose rusty-red hue in fall and winter
-gives much of the state its characteristic
-color.</p>
-<p>These plains are rarely broken by
-cultivation and only a few houses with
-their few trees break the landscape.
-The land&rsquo;s major change comes where
-the Niobrara River, here little more
-than a narrow creek, cuts a valley
-whose rock outcroppings provide homes
-for rock wrens, chipmunks, and bushy-tailed
-wood rats better known as pack
-or trade rats.</p>
-<div class="img" id="fig44">
-<img src="images/i28c.jpg" alt="" width="614" height="600" />
-<p class="pcap">Swainson&rsquo;s hawk</p>
-</div>
-<p>Here, since 1967, near Agate Fossil
-Beds National Monument, my partner
-and I have taken part in the annual
-Breeding Bird Survey for the U.S. Fish
-and Wildlife Service. Part of one of our
-survey routes, Highway 29, crosses the
-monument&rsquo;s west end. We know the
-area&mdash;in June at least&mdash;quite intimately,
-when there is nothing quite so
-beautiful as a sunrise over these flower-dotted,
-green-grassed rolling hills along
-the Niobrara.</p>
-<p>We go many kilometers and make
-many bird counting stops, then we
-drop into the little valley where the
-Niobrara flows and suddenly we hear
-and see birds in such rapid succession
-that we have difficulty getting them all
-named in the three minutes allowed us
-under the survey rules. Actually, three
-stops are influenced by the river: on
-the south edge we have found a common
-nighthawk, a lark sparrow, and
-a Say&rsquo;s phoebe; on the north end the
-rock wren sings its un-wrenlike song.
-Near the bridge, where a narrow belt
-of shrubs and trees&mdash;mostly willows&mdash;hugs
-the river, we have logged the following:
-common flicker, a red-headed
-woodpecker, eastern and western
-kingbirds, western wood peewees, a
-blue jay, black-capped chickadees,
-house wrens, a brown thrasher, robins,
-yellow warblers, black-billed magpies,
-common grackles, black-headed grosbeaks,
-American goldfinches, and the
-non-native house sparrow and starling.
-Only once did we see or hear a black-billed
-cuckoo.</p>
-<p><span class="lr"><i>continues on <a href="#Page_85">page 85</a></i></span></p>
-<div class="pb" id="Page_82">82</div>
-<div class="img" id="fig45">
-<img src="images/i29.jpg" alt="" width="400" height="604" />
-<p class="pcap">Red-winged blackbird chick</p>
-</div>
-<div class="img" id="fig46">
-<img src="images/i29a.jpg" alt="" width="400" height="622" />
-<p class="pcap">Long-billed curlew chick</p>
-</div>
-<div class="img" id="fig47">
-<img src="images/i29b.jpg" alt="" width="400" height="620" />
-<p class="pcap">Long-billed marsh wren</p>
-</div>
-<div class="img" id="fig48">
-<img src="images/i29g.jpg" alt="" width="600" height="436" />
-<p class="pcap">Canada geese</p>
-</div>
-<div class="img" id="fig49">
-<img src="images/i29h.jpg" alt="" width="600" height="438" />
-<p class="pcap">Long-billed curlew male</p>
-</div>
-<div class="img" id="fig50">
-<img src="images/i29i.jpg" alt="" width="600" height="436" />
-<p class="pcap">House wren</p>
-</div>
-<div class="pb" id="Page_83">83</div>
-<div class="img" id="fig51">
-<img src="images/i29j.jpg" alt="" width="600" height="429" />
-<p class="pcap">Nighthawk</p>
-</div>
-<div class="img" id="fig52">
-<img src="images/i29k.jpg" alt="" width="600" height="430" />
-<p class="pcap">Marsh hawk chicks</p>
-</div>
-<div class="img" id="fig53">
-<img src="images/i29l.jpg" alt="" width="600" height="434" />
-<p class="pcap">Killdeer</p>
-</div>
-<div class="img" id="fig54">
-<img src="images/i29m.jpg" alt="" width="400" height="605" />
-<p class="pcap">Great horned owl</p>
-</div>
-<div class="img" id="fig55">
-<img src="images/i29n.jpg" alt="" width="400" height="609" />
-<p class="pcap">Western meadowlark</p>
-</div>
-<div class="img" id="fig56">
-<img src="images/i29o.jpg" alt="" width="400" height="609" />
-<p class="pcap">American bittern</p>
-</div>
-<div class="pb" id="Page_84">84</div>
-<div class="img" id="fig57">
-<img src="images/i30.jpg" alt="" width="400" height="608" />
-<p class="pcap">Pocket gopher</p>
-</div>
-<div class="img" id="fig58">
-<img src="images/i30b.jpg" alt="" width="400" height="610" />
-<p class="pcap">Jackrabbit</p>
-</div>
-<div class="img" id="fig59">
-<img src="images/i30d.jpg" alt="" width="400" height="617" />
-<p class="pcap">Hognose snake</p>
-</div>
-<div class="img" id="fig60">
-<img src="images/i30f.jpg" alt="" width="600" height="435" />
-<p class="pcap">Fence lizard</p>
-</div>
-<div class="img" id="fig61">
-<img src="images/i30g.jpg" alt="" width="600" height="434" />
-<p class="pcap">Coyote</p>
-</div>
-<div class="img" id="fig62">
-<img src="images/i30h.jpg" alt="" width="600" height="437" />
-<p class="pcap">Pronghorn</p>
-</div>
-<div class="pb" id="Page_85">85</div>
-<p>If we stop and peer into a large culvert
-under the highway we may scare
-out a cloud of cliff swallows whose mud
-nests are stuck on culvert walls. Barn
-and rough-winged swallows are more
-rarely seen&mdash;usually near the Agate
-buildings.</p>
-<p>Near scattered farmhouses we may
-see logger-head shrikes; by one water
-tank we usually find a few killdeer.
-These and such birds as the long-billed
-curlew, upland sandpipers, and sharp-tailed
-grouse break the near monotony
-of such prairie birds as western meadowlarks
-(Nebraska&rsquo;s state bird), lark
-buntings, horned larks, and chestnut-collared
-longspurs. Lark buntings line
-the utility wires, taking off to sing their
-territorial songs, and descending with
-butterfly-like motions.</p>
-<p>Hawks are here&mdash;red-tails, Swainson&rsquo;s,
-ferruginous, marsh, and the little
-American kestrel&mdash;but in small
-numbers. We search long rows of fence
-posts for a burrowing owl and occasionally
-see one. Great-horned owls
-frequent tall cottonwood trees around
-the Agate ranch buildings. This is also
-the country of turkey vultures, golden
-eagles, and prairie falcons, but we have
-not been lucky enough to see them yet.</p>
-<p>Mammals are more elusive. Cattle
-pasture conspicuously on land formerly
-claimed by the buffalo (bison).
-We see pronghorns each year. A lone
-coyote is the only other relatively large
-mammal we have logged. Check a
-good mammal book and you will appreciate
-what lives here largely invisible
-to the untrained eye: shrews,
-moles, bats, cottontails and two kinds
-of jackrabbits, pocket gophers, prairie
-dogs, kangaroo rats, voles, several
-kinds of mice, two kinds of ground
-squirrel, muskrats, beaver, raccoons,
-minks, badgers, longtailed weasels,
-two kinds of skunks, occasional porcupines
-and bobcats, white-tailed deer,
-and mule deer. Consider yourself lucky
-if you see the swift fox, mountain lion,
-and the rare black-footed ferret.</p>
-<p>Life abounds here in other forms less
-noticeable to eyes trained on the
-Breeding Bird Survey: various species
-of amphibians, reptiles, fish, and the
-numerous insects associated with
-grasslands. We hear perhaps too much
-about rattlesnakes&mdash;western Nebraska
-has only the prairie rattler, whose
-numbers are now much reduced. Other
-snakes include western hognosed, blue
-racer, bullsnake, and the plains, wandering,
-and red-sided garter snakes.</p>
-<div class="pb" id="Page_86">86</div>
-<h3 class="interlude" id="c13">Collections of Agate Springs Fossils</h3>
-<h4 class="left">Museums You Can Visit</h4>
-<p>Many museums throughout the world have displays of fossils from the Agate
-Fossil Beds. Very few of them actually collected their own material. Museum
-curators are dedicated &ldquo;horse traders&rdquo; and fossil-swapping is part of the business.
-When museums such as the Carnegie Museum of Pittsburgh or the
-American Museum of Natural History in New York make collections like the
-ones made at Agate earlier in this century, they usually have some trading
-stock left over after completing their study collections and exhibits. They
-then can trade an extra <i>Menoceras</i> slab, for example, for a dinosaur skeleton
-from some faraway corner of the Earth.</p>
-<p>At several museums in this country you can see mounted skeletons of several
-animals found at Agate, along with <i>Menoceras</i> slabs (sections of rock with
-the bones still imbedded) or models and dioramas of Agate specimens. To the
-right are listed, in order of proximity to the park, some of the museums and
-their specimens from Agate.</p>
-<p>The United States Museum of Natural History, Smithsonian Institution,
-has many fossils that depict the life of the most recent 65 million years and
-several murals by artist Jay H. Matternes showing the life of each of the
-epochs. The Miocene mural, reproduced on pages <a href="#Page_20">20-21</a> of this handbook,
-is among these reconstructions. It depicts ancient life around what is
-today known as Agate Fossil Beds National Monument.</p>
-<table class="center" summary="">
-<tr><td colspan="2" class="l"><b>The Trailside Museum</b><br />Fort Robinson, Nebraska 69339.</td></tr>
-<tr><td class="c"><img class="icon" src="images/s_menoceras.jpg" alt="Menoceras" width="157" height="83" /> </td><td class="l"><i>Menoceras</i> slab, skeleton, and restoration</td></tr>
-<tr><td class="c"><img class="icon" src="images/s_stenomylus.jpg" alt="Stenomylus" width="157" height="110" /> </td><td class="l"><i>Stenomylus</i> skeleton on a slab, and a prepared limb</td></tr>
-<tr><td class="c"><img class="icon" src="images/s_palaeocastor.jpg" alt="Palaeocastor" width="133" height="47" /> </td><td class="l"><i>Palaeocastor</i> in a <i>Daemonelix</i><br /><i>Palaeocastor</i> in a plaster cast</td></tr>
-<tr><td colspan="2" class="l"><hr class="w" /><br /><b>Museum of Geology, South Dakota School of Mines and Technology</b><br />Rapid City, South Dakota 57701.</td></tr>
-<tr><td class="c"><img class="icon" src="images/s_menoceras.jpg" alt="Menoceras" width="157" height="83" /> </td><td class="l"><i>Menoceras</i> slab, beautifully prepared</td></tr>
-<tr><td colspan="2" class="l"><hr class="w" /><br /><b>The Geological Museum</b><br />University of Wyoming, Laramie, Wyoming 82070.</td></tr>
-<tr><td class="c"><img class="icon" src="images/s_menoceras.jpg" alt="Menoceras" width="157" height="83" /> </td><td class="l"><i>Menoceras</i>, mounted skeleton</td></tr>
-<tr><td class="c"><img class="icon" src="images/s_stenomylus.jpg" alt="Stenomylus" width="157" height="110" /> </td><td class="l"><i>Stenomylus</i> slab containing most of a skeleton</td></tr>
-<tr><td colspan="2" class="l"><hr class="w" /><br /><b>University of Nebraska State Museum</b><br />101 Morrill Hall, 14th and U Streets, Lincoln, Nebraska 68508.</td></tr>
-<tr><td class="c"><img class="icon" src="images/s_moropus.jpg" alt="Moropus" width="133" height="159" /> </td><td class="l"><i>Moropus</i>, mounted skeleton</td></tr>
-<tr><td class="c"><img class="icon" src="images/s_palaeocastor.jpg" alt="Palaeocastor" width="133" height="47" /> </td><td class="l"><i>Palaeocastor</i> skeleton in a <i>Daemonelix</i>; also, two other <i>Daemonelix</i></td></tr>
-<tr><td class="c"><img class="icon" src="images/s_menoceras.jpg" alt="Menoceras" width="157" height="83" /> </td><td class="l"><i>Menoceras</i> slab</td></tr>
-<tr><td class="c"><img class="icon" src="images/s_dinohyus.jpg" alt="Dinohyus" width="152" height="106" /> </td><td class="l"><i>Dinohyus</i> skeleton</td></tr>
-<tr><td class="c"><img class="icon" src="images/s_stenomylus.jpg" alt="Stenomylus" width="157" height="110" /> </td><td class="l"><i>Stenomylus</i>, a group of skeletons</td></tr>
-<tr><td colspan="2" class="l"><hr class="w" /><br /><b id="Page_87">Field Museum of Natural History</b><br />Roosevelt Road at Lake Shore Drive, Chicago, Illinois 60605.</td></tr>
-<tr><td class="c"><img class="icon" src="images/s_menoceras.jpg" alt="Menoceras" width="157" height="83" /> </td><td class="l"><i>Menoceras</i> slab</td></tr>
-<tr><td class="c"><img class="icon" src="images/s_moropus.jpg" alt="Moropus" width="133" height="159" /> </td><td class="l"><i>Moropus</i> skeleton</td></tr>
-<tr><td colspan="2" class="l"><hr class="w" /><br /><b>The University of Michigan Exhibit Museum</b><br />1109 Geddes Rd., Ann Arbor, Michigan 48104.</td></tr>
-<tr><td class="c"><img class="icon" src="images/s_menoceras.jpg" alt="Menoceras" width="157" height="83" /> </td><td class="l"><i>Menoceras</i> slab and mounted skeleton</td></tr>
-<tr><td class="c"><img class="icon" src="images/s_dinohyus.jpg" alt="Dinohyus" width="152" height="106" /> </td><td class="l"><i>Dinohyus</i> eating dead Menoceras, a diorama</td></tr>
-<tr><td class="c"><img class="icon" src="images/s_stenomylus.jpg" alt="Stenomylus" width="157" height="110" /> </td><td class="l"><i>Stenomylus</i> skeleton and model</td></tr>
-<tr><td colspan="2" class="l"><hr class="w" /><br /><b>Carnegie Museum</b><br />4400 Forbes Ave., Pittsburgh, Pennsylvania 15213.</td></tr>
-<tr><td class="c"><img class="icon" src="images/s_promerycochoerus.jpg" alt="Promerycochoerus" width="128" height="61" /> </td><td class="l"><i>Promerycochoerus</i> slab</td></tr>
-<tr><td class="c"><img class="icon" src="images/s_menoceras.jpg" alt="Menoceras" width="157" height="83" /> </td><td class="l"><i>Menoceras</i> slab and mounted skeleton</td></tr>
-<tr><td class="c"><img class="icon" src="images/s_moropus.jpg" alt="Moropus" width="133" height="159" /> </td><td class="l"><i>Moropus</i>, mounted skeleton</td></tr>
-<tr><td class="c"><img class="icon" src="images/s_dinohyus.jpg" alt="Dinohyus" width="152" height="106" /> </td><td class="l"><i>Dinohyus</i>, mounted skeleton</td></tr>
-<tr><td class="c"><img class="icon" src="images/s_stenomylus.jpg" alt="Stenomylus" width="157" height="110" /> </td><td class="l"><i>Stenomylus</i>, three skeletons mounted in a group</td></tr>
-<tr><td colspan="2" class="l"><hr class="w" /><br /><b>The American Museum of Natural History</b><br />Central Park West and 79th St., New York, New York 10024.</td></tr>
-<tr><td class="c"><img class="icon" src="images/s_moropus.jpg" alt="Moropus" width="133" height="159" /> </td><td class="l"><i>Moropus</i> skeleton</td></tr>
-<tr><td class="c"><img class="icon" src="images/s_menoceras.jpg" alt="Menoceras" width="157" height="83" /> </td><td class="l"><i>Menoceras</i> slab and skulls, one used in a sequence showing collecting and preparation techniques</td></tr>
-<tr><td class="c"><img class="icon" src="images/s_dinohyus.jpg" alt="Dinohyus" width="152" height="106" /> </td><td class="l"><i>Dinohyus</i> skull</td></tr>
-<tr><td class="c"><img class="icon" src="images/s_stenomylus.jpg" alt="Stenomylus" width="157" height="110" /> </td><td class="l"><i>Stenomylus</i>, nine skeletons and a reconstruction of the group in life</td></tr>
-<tr><td colspan="2" class="l"><hr class="w" /><br /><b>Museum of Comparative Zoology</b><br />Harvard University, Oxford Street, Cambridge, Massachusetts 02138.</td></tr>
-<tr><td class="c"><img class="icon" src="images/s_menoceras.jpg" alt="Menoceras" width="157" height="83" /> </td><td class="l"><i>Menoceras</i> slab</td></tr>
-<tr><td class="c"><img class="icon" src="images/s_dinohyus.jpg" alt="Dinohyus" width="152" height="106" /> </td><td class="l"><i>Dinohyus</i> skeleton</td></tr>
-<tr><td class="c"><img class="icon" src="images/s_stenomylus.jpg" alt="Stenomylus" width="157" height="110" /> </td><td class="l"><i>Stenomylus</i> skeleton</td></tr>
-</table>
-<div class="pb" id="Page_88">88</div>
-<h3 class="interlude" id="c14">NPS Areas With Fossil Exhibits</h3>
-<p>Several fossil sites in the United States
-are under the protection of the National
-Park Service. Besides Agate, the
-major ones are:</p>
-<h4 id="ccc22">Badlands National Park, South Dakota</h4>
-<div class="img" id="fig63">
-<img src="images/i32.jpg" alt="" width="614" height="600" />
-<p class="pcap">Badlands</p>
-</div>
-<p>Prominent deposits from the
-Oligocene Epoch, predecessor to the
-Miocene, combine with a rugged,
-eroded landscape and abundant wildlife
-to make Badlands a park where the
-natural processes of the past combine
-with those of today. The National Park
-Service maintains a Fossil Exhibit Trail
-at Badlands and presents fossil cleaning
-demonstrations. Prominent fossils
-are those of ancient camels, giant pigs,
-sabertooth cats, <i>Protoceras</i>, and <i>Brontotheres</i>.
-Mailing address: P.O. Box 6,
-Interior, SD 57750.</p>
-<h4 id="ccc23">Dinosaur National Monument, Colorado and Utah</h4>
-<div class="img" id="fig64">
-<img src="images/i32a.jpg" alt="" width="610" height="600" />
-<p class="pcap">Dinosaur</p>
-</div>
-<p>The late Jurassic muds
-and sands of the Morrison Formation
-have been a major source of dinosaur
-bones for more than a century. Steeply
-tilted strata near Vernal, Utah, were
-the source of tons of bones for the
-Carnegie Museum of Pittsburgh. This
-quarry site became the nucleus of Dinosaur
-National Monument. The bone-bearing
-stratum has been exposed by
-careful excavation, so that bones and
-partial skeletons of numerous dinosaurs
-are exposed in high relief. The
-entire quarry face is covered by a glass-walled
-structure that forms a large gallery.
-Mailing address: 4545 E. Hwy. 40,
-Dinosaur, CO 81610.</p>
-<h4 id="ccc24">Florissant Fossil Beds National Monument, Colorado</h4>
-<p>This site has long
-been famous for its fossils of insects
-and plants preserved in fine-grained
-sediments. Specimens of <i>Brontothere</i>
-indicate an Eocene age for the deposits.
-Mailing address: P.O. Box 185,
-Florissant, CO 80816.</p>
-<div class="pb" id="Page_89">89</div>
-<div class="img" id="fig65">
-<img src="images/i32b.jpg" alt="" width="614" height="600" />
-<p class="pcap">Florissant</p>
-</div>
-<h4 id="ccc25">Fossil Butte National Monument, Wyoming</h4>
-<p>Within the strata of this rock
-remnant of an ancient lake is one of
-the most extensive concentrations of
-fossilized freshwater fish known to
-science. The site is about 18 kilometers
-(11 miles) west of Kemmerer,
-Wyoming. Mailing address: P.O. Box
-592, Kemmerer, WY 83101.</p>
-<h4 id="ccc26">Petrified Forest National Park, Arizona</h4>
-<div class="img" id="fig66">
-<img src="images/i32c.jpg" alt="" width="607" height="598" />
-<p class="pcap">Petrified Forest</p>
-</div>
-<p>Here in the Late Triassic Chinle
-Formation are widespread deposits of
-petrified logs. Some are nearly 2
-meters in diameter and 60 meters long
-(6.5 by 197 feet). Preserved in bright
-colors of opal and other minerals, the
-most common trees are relatives of the
-living monkey puzzle or Hawaiian star
-pine. Paleontologists believe many of
-the logs floated to the area in Triassic
-rivers and became stranded. In the
-museum are displays of various fossil
-plant species and animal fossils from
-the same deposits. Mailing address:
-P.O. Box 2217, Petrified Forest National
-Park, AZ 86028.</p>
-<h4 id="ccc27">John Day Fossil Beds National Monument, Oregon</h4>
-<p>With a total of about
-5,700 hectares (14,100 acres) in several
-noncontiguous units in north-central
-Oregon, this park provides an extensive
-record of Earth history dating
-back at least 37 million years. Plant
-and animal fossils are present in great
-variety. Mailing address: HCR 82, Box
-126, Kimberly, OR 97848.</p>
-<h4 id="ccc28">Hagerman Fossil Beds National Monument, Idaho</h4>
-<p>Within the banks of
-the Snake River are preserved the last
-vestiges of late Pliocene life before the
-Ice Age and modern flora and fauna
-appeared. Mailing address: P.O. Box
-570, Hagerman, ID 83332.</p>
-<div class="pb" id="Page_90">90</div>
-<h3 class="interlude" id="c15">Nearby National Parks</h3>
-<p>While you&rsquo;re in the Agate Fossil Beds
-area, why not see some other sites in
-the National Park System? These parks
-offer a variety of experiences from
-frontier history presentations to caving.</p>
-<p class="tb"><b><a id="ccc29">Badlands National Park</a></b> is 97 kilometers
-(60 miles) southeast of Rapid City,
-South Dakota. This wonderland of bizarre,
-colorful spires and pinnacles, massive
-buttes, and deep gorges is open all
-year, though blizzards may temporarily
-block roads in the winter. Campfire programs
-and guided nature walks are presented.
-Backpackers will enjoy the park&rsquo;s
-wilderness area. The park has a herd of
-about 300 bison and some prairie dog
-towns. Mailing address: P.O. Box 6,
-Interior, SD 57750.</p>
-<div class="img" id="fig67">
-<img src="images/i33.jpg" alt="" width="599" height="600" />
-<p class="pcap">Devils Tower</p>
-</div>
-<p class="tb"><b><a id="ccc30">Devils Tower National Monument</a></b> is
-47 kilometers (29 miles) northwest of
-Sundance, Wyoming. Known as Mato
-Tipila (Bear Lodge) to the Lakota, this
-towering landmark looms over the
-Belle Fourche River in the northeast
-corner of Wyoming. Here the Black
-Hills meet the plains grasslands, and
-you will likely see prairie dogs, as well
-as other mammals and a variety of
-birds. The park is open all year. Mailing
-address: P.O. Box 10, Devils Tower,
-WY 82714.</p>
-<div class="img" id="fig68">
-<img src="images/i33a.jpg" alt="" width="602" height="600" />
-<p class="pcap">Fort Laramie</p>
-</div>
-<p class="tb"><b><a id="ccc31">Fort Laramie National Historic Site</a></b>
-is 5 kilometers (3 miles) southwest of
-Fort Laramie, Wyoming. The first fort
-on the site was built in 1834 and soon
-became a lucrative center of the fur
-trade. The U.S. Army took over in
-1849, using the fort to protect the Oregon
-Trail. The fort was abandoned by
-the Army in 1890. Several buildings
-are furnished as they would have been
-during the Army years of the 1870s
-and 1880s. The park is open all year.
-Mailing address: HC 72, Box 389, WY
-82212.</p>
-<div class="pb" id="Page_91">91</div>
-<p class="tb"><b><a id="ccc32">Jewel Cave National Monument</a></b> is located
-on U.S. 16, 24 kilometers (15
-miles) west of Custer, South Dakota.
-The cave&rsquo;s name comes from the myriads
-of jewel-like calcite crystals that
-adorn its walls. Tours are conducted
-daily from mid-May through September.
-Tours, if any, the rest of the year
-are irregular. Mailing address: RR 1,
-Box 60 AA, Custer, SD 57730.</p>
-<div class="img" id="fig69">
-<img src="images/i33b.jpg" alt="" width="605" height="600" />
-<p class="pcap">Mount Rushmore</p>
-</div>
-<p class="tb"><b><a id="ccc33">Mount Rushmore National Memorial</a></b>
-is 40 kilometers (25 miles) southwest
-of Rapid City, South Dakota. The
-mountain sculpture of Washington,
-Jefferson, Theodore Roosevelt, and
-Lincoln is best viewed under morning
-light. From June 1 to Labor Day the
-faces are illuminated at night. The park
-is open all year. Mailing address: P.O.
-Box 268, Keystone, SD 57751.</p>
-<div class="img" id="fig70">
-<img src="images/i33c.jpg" alt="" width="616" height="600" />
-<p class="pcap">Scotts Bluff</p>
-</div>
-<p class="tb"><b><a id="ccc34">Scotts Bluff National Monument</a></b> is 8
-kilometers (5 miles) southwest of
-Scottsbluff, Nebraska. This massive
-rock promontory rises 245 meters (800
-feet) above the valley floor, and it
-served as a landmark to Indians, fur
-traders, and settlers traveling the Oregon
-Trail. It was named for a fur trapper,
-Hiram Scott, and has remained a
-symbol of the great overland migrations.
-The park is open all year. Mailing
-address: P.O. Box 27, Gering, NE
-69341.</p>
-<p class="tb"><b><a id="ccc35">Wind Cave National Park</a></b> is 16 kilometers
-(10 miles) north of Hot Springs
-in southwest South Dakota. Two worlds
-meet here: the underground world of
-the cave and the life of the surface prairie.
-The cave gets its name from the
-wind blowing into or out of the cave.
-Mailing address: RR 1, Box 190, Hot
-Springs, SD 57747.</p>
-<div class="pb" id="Page_92">92</div>
-<h3 class="interlude" id="c16">Not So Nearby National Parks</h3>
-<p>By expanding your travel perimeter
-even farther beyond Agate Fossil Beds,
-you can take in these other National
-Park System sites.</p>
-<p class="tb"><b><a id="ccc36">Bighorn Canyon National Recreation Area</a></b>
-straddles the Montana-Wyoming
-border, 67 kilometers (42 miles) from
-Hardin, Montana, and at Lovell, Wyoming.
-Access to boat ramps and
-campgrounds is from both ends of the
-long reservoir. Yellowtail Dam tours
-are given from Memorial Day to Labor
-Day. The visitor centers are open all
-year. Mailing address: P.O. Box 458,
-Fort Smith, Montana 59035.</p>
-<p class="tb"><b><a id="ccc37">Little Bighorn Battlefield National Monument</a></b>
-is 24 kilometers (15 miles)
-south of Hardin, Montana. Here on
-June 25, 1876, Lt. Col. George Armstrong
-Custer and five 7th Cavalry companies
-attacked and were surrounded
-and killed by Indians. Mailing address:
-P.O. Box 39, Crow Agency, MT 59022.</p>
-<div class="img" id="fig71">
-<img src="images/i34.jpg" alt="" width="606" height="600" />
-<p class="pcap">Rocky Mountain</p>
-</div>
-<p class="tb"><b><a id="ccc38">Rocky Mountain National Park</a></b> is
-northwest of Denver and about 3 kilometers
-(2 miles) west of the community
-of Estes Park, Colorado. The
-park is one of America&rsquo;s most accessible
-mountainous areas. Trail Ridge,
-which crosses the Continental Divide,
-offers breathtaking views. Elk, mule
-deer, bear, cougar, and bighorn sheep
-roam mountain crags, meadows, and
-valleys. Mailing address: Estes Park,
-CO 80517.</p>
-<div class="img" id="fig72">
-<img src="images/i34a.jpg" alt="" width="605" height="600" />
-<p class="pcap">Theodore Roosevelt</p>
-</div>
-<p class="tb"><b><a id="ccc39">Theodore Roosevelt National Park</a></b> is on
-Interstate 94 at Medora, North Dakota.
-A separate unit is 90 kilometers
-(56 miles) north on U.S. 85. In these
-magnificantly colored badlands along
-the Little Missouri River Roosevelt
-had an open-range ranch and developed
-his practical conservation philosophy.
-Both units have campgrounds.
-Mailing address: P.O. Box 7, Medora,
-ND 58645.</p>
-<div class="pb" id="Page_93">93</div>
-<h3 class="interlude" id="c17">Armchair Explorations</h3>
-<h4 id="ccc40">Some Books You May Want to Read</h4>
-<blockquote>
-<p>Bartlett, Richard A., <i>Great Surveys of
-the American West</i>, University of
-Oklahoma Press, 1962.</p>
-<p>Camp, Charles L., <i>Earth Song: A Prologue
-to History</i>, American West Publishing
-Co., 1970.</p>
-<p>Colbert, Edwin H., <i>Evolution of the
-Vertebrates</i>, John Wiley and Sons,
-Inc., 1969.</p>
-<p>Cook, Harold J., <i>Tales of the 04 Ranch</i>,
-University of Nebraska Press, 1968.</p>
-<p>Cook, James H., <i>Fifty Years on the Old
-Frontier</i>, University of Oklahoma Press,
-1980.</p>
-<p>Gould, Stephen Jay, <i>Ever Since Darwin:
-Reflections in Natural History</i>,
-W. W. Norton and Co., 1977.</p>
-<p>Howard, Robert West, <i>The Dawn-seekers</i>,
-Harcourt Brace Jovanovich,
-1975.</p>
-<p>Johnson, Kirk R. and Richard K.
-Stucky, <i>Prehistoric Journey: A History
-of Life on Earth</i>, Roberts Rinehart,
-1995.</p>
-<p>Lanham, Url, <i>The Bone Hunters</i>,
-Columbia University Press, 1973.</p>
-<p>Laporte, L&eacute;o F., <i>Evolution and the
-Fossil Record</i>, W. H. Freeman Co.,
-1978.</p>
-<p>Larson, Robert W., <i>Red Cloud: Warrior-Statesman
-of the Lakota Sioux</i>,
-University of Oklahoma Press, 1997.</p>
-<p>Mason, Stephen F., <i>A History of the
-Sciences</i>, Collier Books, 1970.</p>
-<p>Meade, Dorothy Cook, <i>Heart Bags &amp;
-Handshakes: The Story of the Cook
-Collection</i>, National Woodlands Pub.
-Co., 1994.</p>
-<p>Osborn, Henry F., <i>Cope: Master Naturalist</i>,
-Princeton University Press,
-1931.</p>
-<p>Paul, R. Eli, <i>Autobiography of Red
-Cloud: War Leader of the Oglalas</i>,
-Montana Historical Society Press,
-1997.</p>
-<p>Plate, Robert, <i>The Dinosaur Hunters:
-Othniel C. Marsh and Edward D.
-Cope</i>, McKay Co., 1964.</p>
-<p>Raup, David M. and Steven M. Stanley,
-<i>Principles of Paleontology</i>, W. H.
-Freeman Co., 1978.</p>
-<p>Romer, Alfred Sherwood, <i>Vertebrate
-Paleontology</i>, University of Chicago
-Press, 1966.</p>
-<p>Schuchert, Charles and Clara Mae
-LeVene, <i>O.C. Marsh: Pioneer in Paleontology</i>,
-Yale University Press, 1940.</p>
-</blockquote>
-<div class="pb" id="Page_94">94</div>
-<h3 id="c18">Index</h3>
-<p class="center"><i>Numbers in italics refer to photographs, illustrations, charts, or maps.</i></p>
-<p class="center"><a href="#index_A" class="ab">A</a> <a href="#index_B" class="ab">B</a> <a href="#index_C" class="ab">C</a> <a href="#index_D" class="ab">D</a> <a href="#index_E" class="ab">E</a> <a href="#index_F" class="ab">F</a> <a href="#index_G" class="ab">G</a> <a href="#index_H" class="ab">H</a> <span class="ab">I</span> <a href="#index_J" class="ab">J</a> <a href="#index_K" class="ab">K</a> <a href="#index_L" class="ab">L</a> <a href="#index_M" class="ab">M</a> <a href="#index_N" class="ab">N</a> <a href="#index_O" class="ab">O</a> <a href="#index_P" class="ab">P</a> <a href="#index_Q" class="ab">Q</a> <a href="#index_R" class="ab">R</a> <a href="#index_S" class="ab">S</a> <a href="#index_T" class="ab">T</a> <a href="#index_U" class="ab">U</a> <a href="#index_V" class="ab">V</a> <a href="#index_W" class="ab">W</a> <span class="ab">X</span> <span class="ab">Y</span> <span class="ab">Z</span></p>
-<dl class="index">
-<dt class="center" id="index_A"><b>A</b></dt>
-<dt><b><i>Aepinacodon</i></b> <i><a href="#Page_54">54-55</a></i>, <a class="pgref" href="#Page_60">60</a></dt>
-<dt><b>Agate Fossil Beds National Monument</b> <a class="pgref" href="#Page_11">11</a>, <a class="pgref" href="#Page_14">14</a>, <a class="pgref" href="#Page_50">50</a>;</dt>
-<dd>animals at, <i><a href="#Page_20">20-22</a></i>, <a href="#Page_24">24-34</a>, <i><a href="#Page_84">84</a></i>;</dd>
-<dd>birding at, <a class="pgref" href="#Page_81">81</a>, <i><a href="#Page_82">82-83</a></i>, <a class="pgref" href="#Page_85">85</a>;</dd>
-<dd>established, <a class="pgref" href="#Page_17">17</a>, <a class="pgref" href="#Page_78">78</a>;</dd>
-<dd>geology of <a class="pgref" href="#Page_23">23</a>, <a href="#Page_47">47-52</a>;</dd>
-<dd>museum specimen of, <a class="pgref" href="#Page_38">38</a>, <i><a href="#Page_86">86-87</a></i>;</dd>
-<dd>topography of, <a class="pgref" href="#Page_7">7</a>;</dd>
-<dd>visitor information <a href="#Page_77">77-80</a></dd>
-<dt><b>Agate Springs Ranch</b> <a class="pgref" href="#Page_7">7</a>, <a class="pgref" href="#Page_10">10</a>, <a class="pgref" href="#Page_17">17</a>;</dt>
-<dd>excavations at, <a class="pgref" href="#Page_38">38</a>, <i><a href="#Page_39">39</a></i>; fossils from, <i><a href="#Page_40">40-41</a></i>, <a href="#Page_86">86-87</a></dd>
-<dt><b>Alligator</b> <i><a href="#Page_54">54-55</a></i>, <a class="pgref" href="#Page_60">60</a></dt>
-<dt><b><a id="x_AmericanMuseumOfNaturalHistory">American Museum of Natural History</a></b> <a class="pgref" href="#Page_14">14</a>, <a class="pgref" href="#Page_38">38</a>, <a class="pgref" href="#Page_52">52</a>, <a class="pgref" href="#Page_87">87</a></dt>
-<dt><b><i>Aplodontia</i></b> <a class="pgref" href="#Page_32">32</a></dt>
-</dl>
-<dl class="index">
-<dt class="center" id="index_B"><b>B</b></dt>
-<dt><b>Badlands National Park, South Dakota</b> <i><a href="#Page_88">88</a></i>, <a class="pgref" href="#Page_90">90</a></dt>
-<dt><b>Barbour, Erwin H.</b> <a class="pgref" href="#Page_11">11</a>, <a class="pgref" href="#Page_14">14</a>, <a class="pgref" href="#Page_38">38</a></dt>
-<dt><b>Big Badlands, South Dakota</b> <a class="pgref" href="#Page_49">49</a>, <a class="pgref" href="#Page_52">52</a></dt>
-<dt><b>Bighorn Canyon National Recreation Area, Montana-Wyoming</b> <a class="pgref" href="#Page_92">92</a></dt>
-<dt><b>Bittern, American</b> <i><a href="#Page_83">83</a></i></dt>
-<dt><b>Blackbird, red-winged</b> <i><a href="#Page_82">82</a></i></dt>
-<dt><b>Bone Cabin, Wyoming</b> <a class="pgref" href="#Page_48">48</a></dt>
-<dt><b>Breeding Bird Survey, U.S. Fish and Wildlife</b> <a class="pgref" href="#Page_81">81</a>, <i><a href="#Page_82">82-83</a></i>, <a class="pgref" href="#Page_85">85</a></dt>
-<dt><b>Buteos</b> (buzzard hawks) <a class="pgref" href="#Page_28">28</a></dt>
-</dl>
-<dl class="index">
-<dt class="center" id="index_C"><b>C</b></dt>
-<dt><b>Cambrian period</b> <i><a href="#Page_46">46</a></i></dt>
-<dt><b>Camels.</b> <i>See</i> <i><a href="#x_Oxydactylus">Oxydactylus</a></i>, <i><a href="#x_Stenomylus">Stenomylus</a></i></dt>
-<dt><b>Camping</b> <a class="pgref" href="#Page_78">78</a></dt>
-<dt><b>Carboniferous period</b> <i><a href="#Page_46">46</a></i></dt>
-<dt><b>Carnegie Hill</b> <i><a href="#Page_12">12-13</a></i>, <a class="pgref" href="#Page_14">14</a>, <a class="pgref" href="#Page_37">37</a>, <a class="pgref" href="#Page_77">77</a></dt>
-<dt><b><a id="x_CarnegieMuseum">Carnegie Museum</a></b> <a class="pgref" href="#Page_14">14</a>, <a class="pgref" href="#Page_38">38</a>, <a class="pgref" href="#Page_39">39</a>, <i><a href="#Page_40">40-41</a></i>, <a class="pgref" href="#Page_69">69</a>, <a class="pgref" href="#Page_87">87</a>, <a class="pgref" href="#Page_88">88</a></dt>
-<dt><b>Carnivores</b>, small <a href="#Page_32">32-34</a></dt>
-<dt><b>Cenozoic Era</b> <i><a href="#Page_46">46</a></i>, <a class="pgref" href="#Page_47">47</a>, <a class="pgref" href="#Page_49">49</a>, <a class="pgref" href="#Page_52">52</a></dt>
-<dt><b>Chalicotheres.</b> <i>See</i> <i><a href="#x_Moropus">Moropus</a></i></dt>
-<dt><b>Cheyenne River</b> <a class="pgref" href="#Page_52">52</a></dt>
-<dt><b>Cleveland, Utah</b> <a class="pgref" href="#Page_48">48</a></dt>
-<dt><b>Colorado Plateau</b> <a class="pgref" href="#Page_49">49</a></dt>
-<dt><b>Como Bluff, Wyoming</b> <a class="pgref" href="#Page_48">48</a></dt>
-<dt><b>Cook, Eleanor Barbour</b> <a class="pgref" href="#Page_14">14</a></dt>
-<dt><b>Cook, Harold</b> <a class="pgref" href="#Page_10">10</a>, <a class="pgref" href="#Page_14">14</a>, <a class="pgref" href="#Page_17">17</a>, <a class="pgref" href="#Page_52">52</a></dt>
-<dt><b>Cook, James H.</b> <i><a href="#Page_6">6</a></i>, <a class="pgref" href="#Page_8">8</a>, <a href="#Page_10">10-11</a>, <a class="pgref" href="#Page_14">14</a>, <a class="pgref" href="#Page_77">77</a>;</dt>
-<dd>buys Agate Springs Ranch, <a class="pgref" href="#Page_7">7</a>, <a class="pgref" href="#Page_10">10</a>;</dd>
-<dd>discovers fossils, <a class="pgref" href="#Page_11">11</a>, <a class="pgref" href="#Page_24">24</a>, <a class="pgref" href="#Page_38">38</a></dd>
-<dt><b>Cook, Kate Graham</b> <a href="#Page_10">10-11</a>, <a class="pgref" href="#Page_14">14</a></dt>
-<dt><b>Cook, Margaret Crozier</b> <a class="pgref" href="#Page_17">17</a></dt>
-<dt><b>Cook Museum of Natural History</b> <a class="pgref" href="#Page_17">17</a></dt>
-<dt><b>Cope, Edward Drinker</b> <i><a href="#Page_9">9</a></i>, <a class="pgref" href="#Page_11">11</a>, <a class="pgref" href="#Page_14">14</a></dt>
-<dt><b>Coyote</b> <i><a href="#Page_84">84</a></i></dt>
-<dt><b>Cretaceous period</b> <i><a href="#Page_46">46</a></i></dt>
-<dt><b>Curlew, long-billed</b> <i><a href="#Page_82">82</a></i></dt>
-<dt><b>Cuvier, Georges</b> <a class="pgref" href="#Page_42">42</a>, <i><a href="#Page_43">43</a></i>, <a class="pgref" href="#Page_45">45</a></dt>
-<dt><b>Custer Battlefield National Monument.</b> <i>See</i> <i><a href="#x_LittleBighornBattlefieldNationalMonument">Little Bighorn Battlefield National Monument</a></i></dt>
-</dl>
-<dl class="index">
-<dt class="center" id="index_D"><b>D</b></dt>
-<dt><b><i>Daemonelix</i></b> <a class="pgref" href="#Page_33">33</a>, <i><a href="#Page_69">69</a></i>, <a class="pgref" href="#Page_70">70</a>, <a class="pgref" href="#Page_86">86</a></dt>
-<dt><b><i>Daphoenodon</i></b> <i><a href="#Page_20">20-21</a></i>, <a class="pgref" href="#Page_22">22</a>, <a class="pgref" href="#Page_32">32</a>, <a class="pgref" href="#Page_38">38</a></dt>
-<dt><b>Darwin, Charles</b> <a class="pgref" href="#Page_43">43</a>, <i><a href="#Page_44">44</a></i>, <a class="pgref" href="#Page_45">45</a></dt>
-<dt><b>Devil&rsquo;s Corkscrew</b> <i><a href="#Page_76">76</a></i></dt>
-<dt><b>Devils Tower National Monument, Wyoming</b> <i><a href="#Page_90">90</a></i></dt>
-<dt><b>Devonian period</b> <i><a href="#Page_46">46</a></i></dt>
-<dt><b><i>Diceratherium</i></b> <a class="pgref" href="#Page_24">24</a>. <i>See also</i> <i><a href="#x_Menoceras">Menoceras</a></i></dt>
-<dt><b><i>Dinohyus</i></b> <i><a href="#Page_20">20-21</a></i>, <a class="pgref" href="#Page_22">22</a>, <a class="pgref" href="#Page_30">30</a>, <a class="pgref" href="#Page_87">87</a></dt>
-<dt><b>Dinosaur National Monument, Colorado and Utah</b> <a class="pgref" href="#Page_42">42</a>, <a class="pgref" href="#Page_48">48</a>, <i><a href="#Page_88">88</a></i></dt>
-<dt><b>Drought</b> <a class="pgref" href="#Page_35">35</a>, <a class="pgref" href="#Page_36">36</a>, <a href="#Page_50">50-51</a></dt>
-</dl>
-<dl class="index">
-<dt class="center" id="index_E"><b>E</b></dt>
-<dt><b>Ecology</b> <a class="pgref" href="#Page_53">53</a>, <a href="#Page_61">61-73</a></dt>
-<dt><b><i>Entelodon</i></b> <a class="pgref" href="#Page_30">30</a></dt>
-<dt><b>Entelodont</b> <a class="pgref" href="#Page_30">30</a></dt>
-<dt><b>Eocene epoch</b> <a class="pgref" href="#Page_25">25</a>, <a class="pgref" href="#Page_27">27</a>, <a class="pgref" href="#Page_29">29</a>, <a class="pgref" href="#Page_31">31</a>, <i><a href="#Page_46">46</a></i>, <a class="pgref" href="#Page_49">49</a>, <a class="pgref" href="#Page_53">53</a>, <a class="pgref" href="#Page_63">63</a>, <a class="pgref" href="#Page_88">88</a></dt>
-<dt><b><i>Equus</i></b> <a class="pgref" href="#Page_63">63</a></dt>
-<dt><b>Excavations</b> <a class="pgref" href="#Page_38">38</a>, <i><a href="#Page_39">39</a></i></dt>
-</dl>
-<dl class="index">
-<dt class="center" id="index_F"><b>F</b></dt>
-<dt><b>Field Museum of Natural History</b> <a class="pgref" href="#Page_87">87</a></dt>
-<dt><b>Flora</b> <a class="pgref" href="#Page_7">7</a>, <a class="pgref" href="#Page_10">10</a>, <a class="pgref" href="#Page_53">53</a>, <i><a href="#Page_54">54-59</a></i>, <a class="pgref" href="#Page_60">60</a>, <a href="#Page_71">71-73</a></dt>
-<dt><b>Florissant Fossil Beds National Monument, Colorado</b> <a class="pgref" href="#Page_53">53</a>, <a class="pgref" href="#Page_88">88</a>, <i><a href="#Page_89">89</a></i></dt>
-<dt><b>Folsom, New Mexico</b> <a class="pgref" href="#Page_14">14</a>;</dt>
-<dd>spearpoint, <a class="pgref" href="#Page_17">17</a></dd>
-<dt><b>Fort Laramie National Historic Site, Wyoming</b> <i><a href="#Page_90">90</a></i></dt>
-<dt><b>Fort Robinson State Park, Nebraska</b> <a class="pgref" href="#Page_50">50</a>, <a class="pgref" href="#Page_77">77</a></dt>
-<dt><b>Fossil Butte National Monument, Wyoming</b> <a class="pgref" href="#Page_89">89</a></dt>
-<dt><b>Fossils</b> <i><a href="#Page_38">38-41</a></i>, <a class="pgref" href="#Page_47">47</a>, <a href="#Page_86">86-89</a></dt>
-</dl>
-<dl class="index">
-<dt class="center" id="index_G"><b>G</b></dt>
-<dt><b>Geological Museum, University of Wyoming</b> <a class="pgref" href="#Page_86">86</a></dt>
-<dt><b>Geology</b> <a class="pgref" href="#Page_35">35</a>, <i><a href="#Page_46">46</a></i>, <a href="#Page_47">47-52</a></dt>
-<dt><b>Geese, Canada</b> <i><a href="#Page_82">82</a></i></dt>
-<dt><b>Gerenuk</b> <a class="pgref" href="#Page_29">29</a></dt>
-<dt><b>Gering Formation</b> <a class="pgref" href="#Page_50">50</a></dt>
-<dt><b>Gopher, pocket</b> <i><a href="#Page_84">84</a></i></dt>
-<dt><b>Graham, Elisha B.</b> <a class="pgref" href="#Page_10">10</a></dt>
-<dt><b>Graham, Mary</b> <a href="#Page_10">10-11</a></dt>
-<dt><b>Grasslands</b> <a class="pgref" href="#Page_26">26</a>, <a class="pgref" href="#Page_35">35</a>, <a class="pgref" href="#Page_51">51</a>, <a class="pgref" href="#Page_61">61</a>, <a href="#Page_71">71-72</a></dt>
-<dt><b><i>Gregorymys</i></b> <a class="pgref" href="#Page_33">33</a></dt>
-<dt><b>Guan</b> <a class="pgref" href="#Page_28">28</a></dt>
-</dl>
-<dl class="index">
-<dt class="center" id="index_H"><b>H</b></dt>
-<dt><b>Hagerman Fossil Beds National Monument, Idaho</b> <a class="pgref" href="#Page_89">89</a></dt>
-<dt><b>Harrison Formation</b> <a class="pgref" href="#Page_23">23</a>, <a class="pgref" href="#Page_50">50</a>, <a class="pgref" href="#Page_63">63</a></dt>
-<dt><b>Hawk</b> <i><a href="#Page_56">56-57</a></i>, <a class="pgref" href="#Page_60">60</a>;</dt>
-<dd>marsh <i><a href="#Page_83">83</a></i>;</dd>
-<dd>nighthawk <i><a href="#Page_83">83</a></i>;</dd>
-<dd>Swainson&rsquo;s <i><a href="#Page_81">81</a></i></dd>
-<dt><b>Horses</b> <a href="#Page_62">62-63</a>, <i><a href="#Page_66">66-67</a></i>. <i>See also</i> <i><a href="#x_Merychippus">Merychippus</a></i>, <i><a href="#x_Miohippus">Miohippus</a></i>, <i><a href="#x_Parahippus">Parahippus</a></i>, <i><a href="#x_Protohippus">Protohippus</a></i></dt>
-<dt><b>Hutton, James</b> <a class="pgref" href="#Page_45">45</a></dt>
-</dl>
-<dl class="index">
-<dt class="center" id="index_J"><b>J</b></dt>
-<dt><b>Jackrabbit</b> <i><a href="#Page_84">84</a></i></dt>
-<dt><b>Jefferson, Thomas</b> <a class="pgref" href="#Page_42">42</a></dt>
-<dt><b>Jewel Cave National Monument, South Dakota</b> <a class="pgref" href="#Page_91">91</a></dt>
-<dt><b>John Day Fossil Beds National Monument, Oregon</b> <a class="pgref" href="#Page_89">89</a></dt>
-<dt><b>Jurassic period</b> <i><a href="#Page_46">46</a></i></dt>
-</dl>
-<dl class="index">
-<dt class="center" id="index_K"><b>K</b></dt>
-<dt><b>Killdeer</b> <i><a href="#Page_83">83</a></i></dt>
-</dl>
-<dl class="index">
-<dt class="center" id="index_L"><b>L</b></dt>
-<dt><b>Laboratory</b> <i><a href="#Page_40">40-41</a></i></dt>
-<dt><b>Lamarck, Jean-Baptiste de</b> <i><a href="#Page_43">43</a></i></dt>
-<dt><b>Laramide Revolution</b> <a class="pgref" href="#Page_49">49</a></dt>
-<dt><b>Linnaeus, Carolus</b> <i><a href="#Page_43">43</a></i></dt>
-<dt><b><a id="x_LittleBighornBattlefieldNationalMonument">Little Bighorn Battlefield National Monument</a></b> <a class="pgref" href="#Page_92">92</a></dt>
-<dt><b>Lucretius</b> (Titus Lucretius Carus) <a class="pgref" href="#Page_42">42</a></dt>
-<dt><b>Lyell, Charles</b> <a class="pgref" href="#Page_42">42</a>, <a class="pgref" href="#Page_43">43</a>, <i><a href="#Page_45">45</a></i></dt>
-</dl>
-<div class="pb" id="Page_95">95</div>
-<dl class="index">
-<dt class="center" id="index_M"><b>M</b></dt>
-<dt><b>Map</b> <i><a href="#Page_78">78</a></i>, <i><a href="#Page_79">79</a></i></dt>
-<dt><b>Marsh, Othniel C.</b> <i><a href="#Page_8">8</a></i>, <i><a href="#Page_9">9</a></i>, <a class="pgref" href="#Page_11">11</a></dt>
-<dt><b>Marsland Formation</b> <a class="pgref" href="#Page_50">50</a>, <a class="pgref" href="#Page_51">51</a></dt>
-<dt><b>Matthew, W. D.</b> <a class="pgref" href="#Page_52">52</a></dt>
-<dt><b>McJunkin, George</b> <a class="pgref" href="#Page_14">14</a></dt>
-<dt><b>Meadowlark, western</b> <i><a href="#Page_83">83</a></i></dt>
-<dt><b><i>Meniscomys</i></b> <a href="#Page_32">32-33</a></dt>
-<dt><b><i><a id="x_Menoceras">Menoceras</a></i></b> <a class="pgref" href="#Page_14">14</a>, <i><a href="#Page_20">20-21</a></i>, <i><a href="#Page_22">22</a></i>, <i><a href="#Page_24">24</a></i>, <a class="pgref" href="#Page_25">25</a>, <a class="pgref" href="#Page_36">36</a>, <a class="pgref" href="#Page_38">38</a>, <a class="pgref" href="#Page_51">51</a>, <a class="pgref" href="#Page_86">86</a>, <a class="pgref" href="#Page_87">87</a></dt>
-<dt><b><i><a id="x_Merychippus">Merychippus</a></i></b> <a class="pgref" href="#Page_52">52</a>, <i><a href="#Page_58">58-59</a></i>, <a class="pgref" href="#Page_60">60</a>, <a href="#Page_62">62-63</a></dt>
-<dt><b><i>Merychyus</i></b> <i><a href="#Page_20">20-21</a></i>, <a class="pgref" href="#Page_22">22</a></dt>
-<dt><b>Mesozoic era</b> <i><a href="#Page_46">46</a></i>, <a href="#Page_47">47-49</a></dt>
-<dt><b>Miocene epoch</b> <i><a href="#Page_46">46</a></i>, <a href="#Page_49">49-52</a>, <a href="#Page_71">71-73</a>;</dt>
-<dd>animals of <a href="#Page_20">20-37</a>, <a class="pgref" href="#Page_62">62</a>, <a class="pgref" href="#Page_63">63</a>, <i><a href="#Page_64">64-69</a></i>, <a class="pgref" href="#Page_70">70</a>;</dd>
-<dd>birds of <a class="pgref" href="#Page_28">28</a></dd>
-<dt><b><i><a id="x_Miohippus">Miohippus</a></i></b> <a href="#Page_25">25-26</a>, <a class="pgref" href="#Page_27">27</a>, <a class="pgref" href="#Page_64">64</a>, <i><a href="#Page_66">66-67</a></i></dt>
-<dt><b>Mississippi Embayment</b> <a class="pgref" href="#Page_35">35</a>, <a class="pgref" href="#Page_49">49</a></dt>
-<dt><b>Monroe Creek Formation</b> <a class="pgref" href="#Page_50">50</a></dt>
-<dt><b>Morrison, Colorado</b> <a class="pgref" href="#Page_48">48</a></dt>
-<dt><b><i><a id="x_Moropus">Moropus</a></i></b> <i><a href="#Page_20">20-21</a></i>, <a class="pgref" href="#Page_22">22</a>, <i><a href="#Page_29">29-30</a></i>, <a href="#Page_86">86-87</a></dt>
-<dt><b>Mount Rushmore National Memorial, South Dakota</b> <i><a href="#Page_91">91</a></i></dt>
-<dt><b>Museum of Comparative Zoology, Harvard University</b> <a class="pgref" href="#Page_87">87</a></dt>
-<dt><b>Museum of Geology, South Dakota School of Mines and Technology</b> <a class="pgref" href="#Page_86">86</a></dt>
-<dt><b>Museums</b>, fossils at <i><a href="#Page_86">86-87</a></i>. <i>See also</i> <i><a href="#x_AmericanMuseumOfNaturalHistory">American Museum of Natural History</a></i>, <i><a href="#x_CarnegieMuseum">Carnegie Museum</a></i></dt>
-</dl>
-<dl class="index">
-<dt class="center" id="index_N"><b>N</b></dt>
-<dt><b><i>Nanotragulus</i></b> <a href="#Page_27">27-28</a></dt>
-<dt><b>National Park Service</b> <a class="pgref" href="#Page_17">17</a>, <a href="#Page_88">88-92</a></dt>
-<dt><b>Nighthawk</b> <i><a href="#Page_83">83</a></i></dt>
-<dt><b><i>Nimravus</i></b> <a class="pgref" href="#Page_32">32</a></dt>
-<dt><b>Niobrara River</b> <a class="pgref" href="#Page_7">7</a>, <i><a href="#Page_16">16</a></i>, <a href="#Page_23">23-24</a>, <a class="pgref" href="#Page_36">36</a>, <a class="pgref" href="#Page_37">37</a>, <a class="pgref" href="#Page_50">50</a>, <i><a href="#Page_54">54-55</a></i>, <i><a href="#Page_60">60</a></i></dt>
-<dt><b>North Platte River</b> <a class="pgref" href="#Page_52">52</a></dt>
-<dt><b><i>Nothocyon</i></b> <a class="pgref" href="#Page_32">32</a>, <a class="pgref" href="#Page_33">33</a></dt>
-</dl>
-<dl class="index">
-<dt class="center" id="index_O"><b>O</b></dt>
-<dt><b>Oglala Sioux Indians</b> <a class="pgref" href="#Page_7">7</a>, <a class="pgref" href="#Page_11">11</a>. <i>See also</i> <i><a href="#x_RedCloud">Red Cloud</a></i></dt>
-<dt><b><i>Oligobunis</i></b> <a class="pgref" href="#Page_32">32</a></dt>
-<dt><b>Oligocene epoch</b> <a class="pgref" href="#Page_25">25</a>, <a class="pgref" href="#Page_31">31</a>, <i><a href="#Page_46">46</a></i>, <a class="pgref" href="#Page_49">49</a>, <a class="pgref" href="#Page_50">50</a>, <a class="pgref" href="#Page_52">52</a>, <a class="pgref" href="#Page_53">53</a>, <a class="pgref" href="#Page_70">70</a>, <a class="pgref" href="#Page_88">88</a>;</dt>
-<dd>animals of <a class="pgref" href="#Page_61">61</a>, <a class="pgref" href="#Page_63">63</a></dd>
-<dt><b>Opossum</b> <i><a href="#Page_54">54-55</a></i>, <a class="pgref" href="#Page_60">60</a></dt>
-<dt><b>Ordovician period</b> <i><a href="#Page_46">46</a></i></dt>
-<dt><b><i>Oreodon</i></b> <a class="pgref" href="#Page_25">25</a>, <i><a href="#Page_54">54-55</a></i>, <a class="pgref" href="#Page_60">60</a>, <a class="pgref" href="#Page_63">63</a></dt>
-<dt><b>Osborn, Henry F.</b> <a class="pgref" href="#Page_14">14</a>, <a class="pgref" href="#Page_38">38</a></dt>
-<dt><b>Owl, great horned</b> <i><a href="#Page_83">83</a></i></dt>
-<dt><b><i><a id="x_Oxydactylus">Oxydactylus</a></i></b> <i><a href="#Page_20">20-21</a></i>, <a class="pgref" href="#Page_22">22</a>, <a class="pgref" href="#Page_28">28</a>, <i><a href="#Page_56">56-57</a></i>, <a class="pgref" href="#Page_60">60</a></dt>
-</dl>
-<dl class="index">
-<dt class="center" id="index_P"><b>P</b></dt>
-<dt><b><i>Palaeocastor</i></b> <a class="pgref" href="#Page_14">14</a>, <i><a href="#Page_20">20-21</a></i>, <a class="pgref" href="#Page_22">22</a>, <i><a href="#Page_33">33</a></i>, <a class="pgref" href="#Page_64">64</a>, <i><a href="#Page_68">68-69</a></i>, <a href="#Page_70">70-71</a>, <a class="pgref" href="#Page_77">77</a>, <a class="pgref" href="#Page_86">86</a></dt>
-<dt><b><i>Palaeolagus</i></b> <a class="pgref" href="#Page_34">34</a></dt>
-<dt><b>Paleocene epoch</b> <i><a href="#Page_46">46</a></i>, <a class="pgref" href="#Page_53">53</a></dt>
-<dt><b>Paleozoic era</b> <i><a href="#Page_46">46</a></i>, <a href="#Page_47">47-48</a></dt>
-<dt><b><i><a id="x_Parahippus">Parahippus</a></i></b> <i><a href="#Page_20">20-21</a></i>, <a class="pgref" href="#Page_22">22</a>, <i><a href="#Page_27">27</a></i>, <i><a href="#Page_56">56-57</a></i>, <a class="pgref" href="#Page_60">60</a>, <a class="pgref" href="#Page_62">62</a>, <a class="pgref" href="#Page_67">67</a></dt>
-<dt><b>Permian period</b> <i><a href="#Page_46">46</a></i></dt>
-<dt><b>Peterson, O. A.</b> <a class="pgref" href="#Page_14">14</a>, <a class="pgref" href="#Page_38">38</a>, <a class="pgref" href="#Page_39">39</a></dt>
-<dt><b>Petrified Forest National Park, Arizona</b> <i><a href="#Page_89">89</a></i></dt>
-<dt><b>Pigs</b> <a href="#Page_30">30-31</a></dt>
-<dt><b>Pine Ridge, South Dakota</b> <a class="pgref" href="#Page_52">52</a></dt>
-<dt><b>Pleistocene epoch</b> <a href="#Page_28">28-29</a>, <i><a href="#Page_46">46</a></i>, <i><a href="#Page_64">64</a></i>, <a class="pgref" href="#Page_67">67</a></dt>
-<dt><b>Pliocene epoch</b> <a href="#Page_24">24-25</a>, <a class="pgref" href="#Page_27">27</a>, <i><a href="#Page_46">46</a></i>, <a class="pgref" href="#Page_52">52</a>, <a class="pgref" href="#Page_63">63</a></dt>
-<dt><b><i>Portheus</i></b> <a class="pgref" href="#Page_48">48</a></dt>
-<dt><b>Precambrian era</b> <i><a href="#Page_46">46</a></i></dt>
-<dt><b><i>Promerycochoerus</i></b> <i><a href="#Page_20">20-21</a></i>, <a class="pgref" href="#Page_22">22</a>, <a class="pgref" href="#Page_25">25</a>, <a class="pgref" href="#Page_87">87</a></dt>
-<dt><b>Pronghorn</b> (artiodactyls) <a class="pgref" href="#Page_63">63</a>, <i><a href="#Page_84">84</a></i>. <i>See also</i> <i><a href="#x_Syndyoceras">Syndyoceras</a></i></dt>
-<dt><b><i>Protoceras</i></b> <a class="pgref" href="#Page_31">31</a></dt>
-<dt><b><i><a id="x_Protohippus">Protohippus</a></i></b> <a class="pgref" href="#Page_62">62</a>, <a class="pgref" href="#Page_63">63</a></dt>
-<dt><b><i>Pseudaelurus</i></b> <a class="pgref" href="#Page_32">32</a>, <i><a href="#Page_58">58-59</a></i>, <a class="pgref" href="#Page_60">60</a></dt>
-</dl>
-<dl class="index">
-<dt class="center" id="index_Q"><b>Q</b></dt>
-<dt><b>Quaternary period</b> <i><a href="#Page_46">46</a></i></dt>
-</dl>
-<dl class="index">
-<dt class="center" id="index_R"><b>R</b></dt>
-<dt><b><a id="x_RedCloud">Red Cloud</a></b> <a class="pgref" href="#Page_9">9</a>, <a class="pgref" href="#Page_11">11</a></dt>
-<dt><b>Rhinoceros</b> <a href="#Page_24">24-25</a>, <a class="pgref" href="#Page_50">50</a>, <a class="pgref" href="#Page_51">51</a>, <a class="pgref" href="#Page_63">63</a></dt>
-<dt><b>Rocky Mountain National Park, Colorado</b> <a class="pgref" href="#Page_92">92</a></dt>
-<dt><b>Rocky Mountain Revolution</b> <a class="pgref" href="#Page_51">51</a>, <a class="pgref" href="#Page_52">52</a></dt>
-<dt><b>Runningwater Formation</b> <a class="pgref" href="#Page_51">51</a></dt>
-<dt><b>Rodents</b> <a href="#Page_32">32-34</a></dt>
-</dl>
-<dl class="index">
-<dt class="center" id="index_S"><b>S</b></dt>
-<dt><b>Sandpiper, upland</b> <i><a href="#Page_14">14</a></i></dt>
-<dt><b>Scotts Bluff National Monument, Nebraska</b> <a class="pgref" href="#Page_49">49</a>, <i><a href="#Page_91">91</a></i></dt>
-<dt><b>Sheep Creek Formation</b> <a class="pgref" href="#Page_52">52</a></dt>
-<dt><b>Silurian period</b> <i><a href="#Page_46">46</a></i></dt>
-<dt><b>Smiley Canyon, Nebraska</b> <a class="pgref" href="#Page_50">50</a></dt>
-<dt><b>Snake, hognose</b> <i><a href="#Page_84">84</a></i></dt>
-<dt><b><i><a id="x_Stenomylus">Stenomylus</a></i></b> <a class="pgref" href="#Page_14">14</a>, <i><a href="#Page_20">20-21</a></i>, <a class="pgref" href="#Page_22">22</a>, <i><a href="#Page_29">29</a></i>, <a class="pgref" href="#Page_37">37</a>, <i><a href="#Page_39">39</a></i>, <a class="pgref" href="#Page_50">50</a>, <i><a href="#Page_64">64-65</a></i>, <a class="pgref" href="#Page_86">86</a>, <a class="pgref" href="#Page_87">87</a>;</dt>
-<dd><i>hitchcocki</i>, <a class="pgref" href="#Page_51">51</a></dd>
-<dt><b>Sundance Formation</b> <a class="pgref" href="#Page_48">48</a></dt>
-<dt><b><i><a id="x_Syndyoceras">Syndyoceras</a></i></b> <i><a href="#Page_20">20-21</a></i>, <a class="pgref" href="#Page_22">22</a>, <i><a href="#Page_31">31</a></i></dt>
-<dt><b><i>Synthetoceras</i></b> <a href="#Page_31">31-32</a></dt>
-</dl>
-<dl class="index">
-<dt class="center" id="index_T"><b>T</b></dt>
-<dt><b>Teeth, high-crowned</b> <a href="#Page_62">62-63</a></dt>
-<dt><b><i>Temnocyon</i></b> <a class="pgref" href="#Page_32">32</a></dt>
-<dt><b>Tertiary period</b> <i><a href="#Page_46">46</a></i>, <a class="pgref" href="#Page_53">53</a></dt>
-<dt><b>Theodore Roosevelt National Park, North Dakota</b> <a class="pgref" href="#Page_92">92</a></dt>
-<dt><b>Thompson, Albert</b> <a class="pgref" href="#Page_14">14</a>, <a class="pgref" href="#Page_38">38</a></dt>
-<dt><b>Toadstool Park, Nebraska</b> <a class="pgref" href="#Page_49">49</a></dt>
-<dt><b>Tortoise</b> <a href="#Page_33">33-34</a></dt>
-<dt><b>Trailside Museum, Nebraska</b> <a class="pgref" href="#Page_86">86</a></dt>
-<dt><b>Triassic period</b> <i><a href="#Page_46">46</a></i></dt>
-</dl>
-<dl class="index">
-<dt class="center" id="index_U"><b>U</b></dt>
-<dt><b>Uniformitarianism</b> <a class="pgref" href="#Page_42">42</a>, <a class="pgref" href="#Page_43">43</a>, <a class="pgref" href="#Page_45">45</a></dt>
-<dt><b>University Hill</b> <a class="pgref" href="#Page_7">7</a>, <i><a href="#Page_12">12-13</a></i>, <a class="pgref" href="#Page_35">35</a>;</dt>
-<dd>digging at, <a class="pgref" href="#Page_14">14</a>;</dd>
-<dd>formation of <a class="pgref" href="#Page_37">37</a>;</dd>
-<dd>tourist facilities at, <a class="pgref" href="#Page_77">77</a></dd>
-<dt><b>University of Nebraska State Museum</b> <a class="pgref" href="#Page_86">86</a></dt>
-</dl>
-<dl class="index">
-<dt class="center" id="index_V"><b>V</b></dt>
-<dt><b>Visitor information</b> <a href="#Page_77">77-80</a>, <a href="#Page_86">86-92</a></dt>
-<dt><b>Von Linne, Karl</b> <i><a href="#Page_43">43</a></i></dt>
-</dl>
-<dl class="index">
-<dt class="center" id="index_W"><b>W</b></dt>
-<dt><b>Wallace, Alfred</b> <i><a href="#Page_45">45</a></i></dt>
-<dt><b>White River</b> <a class="pgref" href="#Page_52">52</a>;</dt>
-<dd>Badlands <a class="pgref" href="#Page_31">31</a>;</dd>
-<dd>Beds <a class="pgref" href="#Page_49">49</a></dd>
-<dt><b>Wildflowers</b> <a class="pgref" href="#Page_7">7</a>, <a class="pgref" href="#Page_10">10</a></dt>
-<dt><b>Wind Cave National Park, South Dakota</b> <a class="pgref" href="#Page_91">91</a></dt>
-<dt><b>Wren</b>, house <i><a href="#Page_82">82</a></i>;</dt>
-<dd>long-billed marsh <i><a href="#Page_82">82</a></i></dd>
-</dl>
-<dl class="undent"><dt>&#9733;GPO: 1999&mdash;454-765/00504</dt>
-<dt>Reprint 1999</dt></dl>
-<div class="pb" id="Page_96">96</div>
-<h2 id="c19"><span class="small">National Park Service</span></h2>
-<p>The National Park Service expresses its appreciation
-to all those persons who made the preparation
-and production of this handbook possible. The
-Service also gratefully acknowledges the financial
-support given this handbook project by the Oregon
-Trail Museum Association, a nonprofit group
-that assists interpretive efforts at Agate Fossil
-Beds National Monument.</p>
-<h4 id="ccc41">Texts</h4>
-<p>James R. and Laurie J. Macdonald, authors of &ldquo;A
-Landscape Rich With Life&rdquo; in <a href="#c3">Part 2</a>, are paleontologists
-who live in Sunnyvale, California, and
-teach nearby.</p>
-<p>Doris B. Gates, writer of &ldquo;Birding Along the
-Niobrara&rdquo; in <a href="#c8">Part 3</a>, is a retired biology professor
-who lives in Chadron, Nebraska.</p>
-<h4 id="ccc42">Maps</h4>
-<p>R.R. Donnelly &amp; Sons Co. <a class="pgref" href="#Page_79">79</a>.</p>
-<h4 id="ccc43">Illustrations</h4>
-<dl class="undent"><dt>Jay H. Matternes, who painted the wildlife panoramas and animal features on the cover and in <a href="#c3">Part 2</a>, is a paleontological reconstruction artist who lives in Fairfax, Virginia. In <a href="#c3">Part 2</a> his illustrations appear on pages <a href="#Page_20">20-21</a>, <a class="pgref" href="#Page_24">24</a>, <a class="pgref" href="#Page_25">25</a>, <a href="#Page_27">27-33</a>, <a href="#Page_54">54-59</a>, <a href="#Page_64">64-69</a>.</dt>
-<dt>American Museum of Natural History <a class="pgref" href="#Page_9">9</a> Cope.</dt>
-<dt>Greg Beaumont <a class="pgref" href="#Page_14">14</a>, <a href="#Page_81">81-84</a>.</dt>
-<dt>Carnegie Museum <a href="#Page_38">38-41</a>.</dt>
-<dt>Library of Congress <a href="#Page_43">43-45</a>.</dt>
-<dt>James O. Milmoe <a href="#Page_12">12-13</a>, <a class="pgref" href="#Page_15">15</a>, <a class="pgref" href="#Page_16">16</a>, <a class="pgref" href="#Page_76">76</a>.</dt>
-<dt>Peabody Museum of Natural History, Yale University <a class="pgref" href="#Page_8">8</a>.</dt>
-<dt>All other illustrations are from the files of Agate Fossil Beds National Monument and the National Park Service.</dt></dl>
-<div class="pb" id="Page_97">97</div>
-<h2 id="c20"><span class="small">U.S. Department of the Interior</span></h2>
-<p>The mission of the Department of the Interior is to
-protect and provide access to our Nation&rsquo;s natural
-and cultural heritage and honor our trust responsibilities
-to tribes. The National Park Service preserves
-unimpaired the natural and cultural resources
-and values of the National Park System for the
-enjoyment, education, and inspiration of this and
-future generations. The National Park Service cooperates
-with partners to extend the benefits of natural
-and cultural resource conservation and outdoor
-recreation throughout this country and the world.</p>
-<div class="pb" id="Page_98">98</div>
-<h2 id="c21"><span class="small">Agate Fossil Beds</span></h2>
-<p class="pcap">
-<i>Through the remains of animals long extinct, excavated here
-at this site, Agate Fossil Beds National Monument tells the
-story of the Miocene Epoch&mdash;the Age of Mammals&mdash;that
-occurred 5 to 23 million years ago. The scene on the
-<a href="#cover">front cover</a> is from a mural by artist Jay H. Matternes that
-depicts animals of the Early Miocene.</i></p>
-<div class="img" id="fig73">
-<img src="images/i35.jpg" alt="" width="600" height="453" />
-<p class="pcap"><i>In addition to fossils,
-the park has an extensive collection of Plains Indian art
-and artifacts, such as this shirt that belonged to Red Cloud.</i></p>
-</div>
-<h2>Transcriber&rsquo;s Notes</h2>
-<ul>
-<li>Retained publication information from the printed edition: this eBook is public-domain in the country of publication.</li>
-<li>Relocated all image captions to be immediately under the corresponding images, removing redundant references like &ldquo;preceding page&rdquo;.</li>
-<li>Silently corrected a few palpable typos.</li>
-<li>In the text versions only, text in italics is delimited by _underscores_.</li>
-<li>Conjecturally restored one subsection of the index entry for &ldquo;Agate Springs Ranch&rdquo;</li>
-</ul>
-
-
-
-
-
-
-
-<pre>
-
-
-
-
-
-End of the Project Gutenberg EBook of Agate Fossil Beds National Monument,
-Nebraska, by United States National Park Service
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