diff options
| author | Roger Frank <rfrank@pglaf.org> | 2025-10-14 20:03:31 -0700 |
|---|---|---|
| committer | Roger Frank <rfrank@pglaf.org> | 2025-10-14 20:03:31 -0700 |
| commit | a1bcfcbb383d07092bde8fdd3497e93776307f85 (patch) | |
| tree | a0d53552bd9ff1e3bda10a9864654d17b46dc0c5 /35316.txt | |
Diffstat (limited to '35316.txt')
| -rw-r--r-- | 35316.txt | 7535 |
1 files changed, 7535 insertions, 0 deletions
diff --git a/35316.txt b/35316.txt new file mode 100644 index 0000000..5190ee5 --- /dev/null +++ b/35316.txt @@ -0,0 +1,7535 @@ +The Project Gutenberg EBook of Dragons of the Air, by H. G. Seeley + +This eBook is for the use of anyone anywhere 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 + + +Title: Dragons of the Air + An Account of Extinct Flying Reptiles + +Author: H. G. Seeley + +Release Date: February 18, 2011 [EBook #35316] + +Language: English + +Character set encoding: ASCII + +*** START OF THIS PROJECT GUTENBERG EBOOK DRAGONS OF THE AIR *** + + + + +Produced by Chris Curnow and the Online Distributed +Proofreading Team at http://www.pgdp.net (This file was +produced from images generously made available by The +Internet Archive) + + + + + + + + + + DRAGONS OF THE AIR + + + + + [Illustration: FIG. 47. RHAMPHORHYNCHUS PHYLLUNUS + + SHOWING THE PRESERVATION OF THE WING MEMBRANES + + _From the Lithographic slate of Eichstaedt, Bavaria_ + + _Frontispiece_] + + + + + DRAGONS OF THE AIR + + AN ACCOUNT OF + EXTINCT FLYING REPTILES + + BY + + H. G. SEELEY, F.R.S. + + PROFESSOR OF GEOLOGY IN KING'S COLLEGE, LONDON; LECTURER ON GEOLOGY + AND MINERALOGY IN THE ROYAL INDIAN ENGINEERING COLLEGE + + WITH EIGHTY ILLUSTRATIONS + + "I AM A BROTHER OF DRAGONS" + _Job_ xxx. 29 + + + NEW YORK: D. APPLETON & CO. + LONDON: METHUEN & CO. + + 1901 + + + + +PREFACE + + +I was a student of law at a time when Sir Richard Owen was lecturing on +Extinct Fossil Reptiles. The skill of the great master, who built bones +together as a child builds with a box of bricks, taught me that the laws +which determine the forms of animals were less understood at that time +than the laws which govern the relations of men in their country. The +laws of Nature promised a better return of new knowledge for reasonable +study. A lecture on Flying Reptiles determined me to attempt to fathom +the mysteries which gave new types of life to the Earth and afterwards +took them away. + +Thus I became the very humble servant of the Dragons of the Air. Knowing +but little about them I went to Cambridge, and for ten years worked with +the Professor of Geology, the late Rev. Adam Sedgwick, LL.D., F.R.S., in +gathering their bones from the so-called Cambridge Coprolite bed, the +Cambridge Greensand. The bones came in thousands, battered and broken, +but instructive as better materials might not have been. My rooms +became filled with remains of existing birds, lizards, and mammals, +which threw light on the astonishing collection of old bones which I +assisted in bringing together for the University. + +In time I had something to say about Flying Animals which was new. The +story was told in the theatre of the Royal Institution, in a series of +lectures. Some of them were repeated in several English towns. There was +still much to learn of foreign forms of flying animals; but at last, +with the aid of the Government grant administered by the Royal Society, +and the chiefs of the great Continental museums, I saw all the specimens +in Europe. + +So I have again written out my lectures, with the aid of the latest +discoveries, and the story of animal structure has lost nothing in +interest as a twice-told tale. It still presents in epitome the story of +life on the Earth. He who understands whence the Flying Reptiles came, +how they endured, and disappeared from the Earth, has solved some of the +greatest mysteries of life. I have only contributed something towards +solving the problems. + +In telling my story, chiefly of facts in Nature, an attempt is made to +show how a naturalist does his work, in the hope that perhaps a few +readers will find happiness in following the workings of the laws of +life. Such an illumination has proved to many worth seeking, a solid +return for labour, which is not to be marketed on the Exchange, but may +be taken freely without exhausting the treasury of Nature's truths. Such +outlines of knowledge as here are offered to a larger public, may also, +I believe, be acceptable to students of science and scientific men. + +The drawings given in illustration of the text have been made for me by +Miss E. B. Seeley. + + H. G. S. + KENSINGTON, _May, 1901_ + + + + +CONTENTS + + + PAGE + CHAPTER I. + FLYING REPTILES 1 + + CHAPTER II. + HOW A REPTILE IS KNOWN 4 + + CHAPTER III. + A REPTILE IS KNOWN BY ITS BONES 11 + + CHAPTER IV. + ANIMALS WHICH FLY 15 + + CHAPTER V. + DISCOVERY OF THE PTERODACTYLE 27 + + CHAPTER VI. + HOW ANIMALS ARE INTERPRETED BY THEIR BONES 37 + + CHAPTER VII. + INTERPRETATION OF PTERODACTYLES BY THEIR SOFT PARTS 45 + + CHAPTER VIII. + THE PLAN OF THE SKELETON 58 + + CHAPTER IX. + THE BACKBONE, OR VERTEBRAL COLUMN 78 + + CHAPTER X. + THE HIP-GIRDLE AND HIND LIMB 93 + + CHAPTER XI. + SHOULDER-GIRDLE AND FORE LIMB 107 + + CHAPTER XII. + EVIDENCES OF THE ANIMAL'S HABITS FROM ITS REMAINS 134 + + CHAPTER XIII. + ANCIENT ORNITHOSAURS FROM THE LIAS 143 + + CHAPTER XIV. + ORNITHOSAURS FROM THE MIDDLE SECONDARY ROCKS 153 + + CHAPTER XV. + ORNITHOSAURS FROM THE UPPER SECONDARY ROCKS 172 + + CHAPTER XVI. + CLASSIFICATION OF THE ORNITHOSAURIA 187 + + CHAPTER XVII. + FAMILY RELATIONS OF PTERODACTYLES TO ANIMALS WHICH LIVED WITH THEM 196 + + CHAPTER XVIII. + HOW PTERODACTYLES MAY HAVE ORIGINATED 213 + + APPENDIX 231 + + INDEX 233 + + + + +LIST OF ILLUSTRATIONS + + FIG. PAGE + 47. Wings of Rhamphorhynchus _Frontispiece_ + 1. Lung of the lung-fish Ceratodus 5 + 2. Attachment of the lower jaw in a Mammal and in a Pterodactyle 12 + 3. Chaldaean Dragon 15 + 4. Winged human figure from the Temple of Ephesus 16 + 5. Flying fish Exocoetus 18 + 6. Flying Frog 19 + 7. Flying Lizard (Draco) 20 + 8. Birds in flight 22 + 9. Flying Squirrel (Pteromys) 24 + 10. Bats, flying and walking 25 + 11. Skeleton of _Pterodactylus longirostris_ 28 + 12. The skeleton restored 29 + 13. The animal form restored 30 + 14. Fore limbs in four types of mammals 38 + 15. Pneumatic foramen in Pterodactyle bone 46 + 16. Lungs of the bird Apteryx 48 + 17. Air cells in the body of an Ostrich 49 + 18. Lung of a Chameleon 51 + 19. Brain in Pterodactyle, Mammal, Bird, and Reptiles 53 + 20. Skull of Kingfisher and Rhamphorhynchus 63 + 21. Skull of Heron and Rhamphorhynchus 65 + 22. Palate of Macrocercus and ? Campylognathus 71 + 23. Lower jaw of Echidna and Ornithostoma 76 + 24. First two neck vertebrae of Ornithocheirus 81 + 25. Middle neck vertebrae of Ornithocheirus 83 + 26. Back vertebra of Ornithocheirus and Crocodile 86 + 27. Sacrum, with hip bones, of Rhamphorhynchus 88 + 28. Extremity of tail of _Rhamphorhynchus phyllurus_ 91 + 29. Hip-girdle bones in Apteryx and Rhamphorhynchus 95 + 30. Pelvis with prepubic bone in Pterodactylus 96 + 31. Pelvis with prepubic bones in Rhamphorhynchus 97 + 32. Pelvis of an Alligator seen from below 98 + 33. Femora: Echidna, Ornithocheirus, Ursus 100 + 34. Tibia and fibula: Dimorphodon and Vulture 102 + 35. Metatarsus and digits in three Pterodactyles 104 + 36. Sternum in Cormorant and Rhamphorhynchus 108 + 37. Sternum in Ornithocheirus 109 + 38. Shoulder-girdle bones in a bird and three Pterodactyles 113 + 39. The Notarium from the back of Ornithocheirus 115 + 40. The shoulder-girdle of Ornithocheirus 115 + 41. Humerus of Pigeon and Ornithocheirus 119 + 42. Fore-arm of Golden Eagle and Dimorphodon 120 + 43. Wrist bones of Ornithocheirus 124 + 44. Clawed digits of the hand in two Pterodactyles 125 + 45. Claw from the hand of Ornithocheirus 129 + 46. The hand in Archaeopteryx and the Ostrich 130 + 48. Slab of Lias with bones of Dimorphodon _To face page_ 143 + 49. Dimorphodon (restored form) at rest 144 + 50. Dimorphodon (restored form of the animal) _To face page_ 145 + 51. Dimorphodon skeleton, walking as a quadruped " " 146 + 52. Dimorphodon skeleton as a biped " " 147 + 53. Lower jaw of Dorygnathus 149 + 54. Dimorphodon (wing membranes spread for flight) _To face page_ 150 + 55. Pelvis of Dimorphodon 151 + 56. Rhamphorhynchus skeleton (restored) 161 + 57. Scaphognathus (restoration of 1875) 163 + 58. Six restorations of Ornithosaurs 164 + 59. Ptenodracon skeleton (restored) 167 + 60. _Cycnorhamphus suevicus_ slab with bones _To face page_ 168 + 61. _Cycnorhamphus suevicus_ (form of the animal) _To face page_ 169 + 62. _Cycnorhamphus suevicus_ skeleton (restored) 170 + 63. _Cycnorhamphus Fraasi_ (restored skeleton form + of the animal) _To face page_ 170 + 64. _Cycnorhamphus Fraasi_ (restoration of the form + of the body) _To face page_ 171 + 65. Neck vertebra of Doratorhynchus from the Purbeck 173 + 66. Neck bone of Ornithodesmus from the Wealden 173 + 67. Sternum of Ornithodesmus, seen from the front 175 + 68. Sternum of Ornithodesmus, side view, showing the keel 175 + 69. Diagram of known parts of skull of Ornithocheirus 177 + 70. Neck bone of Ornithocheirus 179 + 71. Jaws of Ornithocheirus from the Chalk 180 + 72. Palate of the English Toothless Pterodactyle 181 + 73. Two views of the skull of Ornithostoma (Pteranodon) 182 + 74. Skeleton of Ornithostoma 183 + 75. Comparison of six skulls of Ornithosaurs 192 + 76. Pelvis of Ornithostoma 195 + 77. Skull of Anchisaurus and Dimorphodon 199 + 78. Skull of Ornithosuchus and Dimorphodon 201 + 79. The pelvis in Ornithosaur and Dinosaur 204 + 80. The prepubic bones in Dimorphodon and Iguanodon 206 + + These figures are greatly reduced in size, and when two or more + bones are shown in the same figure all are brought to the same size + to facilitate the comparison. + + + + +DRAGONS OF THE AIR + + + + +CHAPTER I + +FLYING REPTILES + + +The history of life on the earth during the epochs of geological time +unfolds no more wonderful discovery among types of animals which have +become extinct than the family of fossils known as flying reptiles. Its +coming into existence, its structure, and passing away from the living +world are among the great mysteries of Nature. + +The animals are astonishing in their plan of construction. In aspect +they are unlike birds and beasts which, in this age, hover over land and +sea. They gather into themselves in the body of a single individual, +structures which, at the present day, are among the most distinctive +characters of certain mammals, birds, and reptiles. + +The name "flying reptile" expresses this anomaly. Its invention is due +to the genius of the great French naturalist Cuvier, who was the first +to realise that this extinct animal, entombed in slabs of stone, is one +of the wonders of the world. + +The word "reptile" has impressed the imagination with unpleasant sound, +even when the habits of the animals it indicates are unknown. It is +familiarly associated with life which is reputed venomous, and is +creeping and cold. Its common type, the serpent, in many parts of the +world takes a yearly toll of victims from man and beast, and has become +the representative of silent, active strength, dreaded craft, and +danger. + +Science uses the word "reptile" in a more exact way, to define the +assemblage of cold-blooded animals which in familiar description are +separately named serpents, lizards, turtles, hatteria, and crocodiles. + +Turtles and the rest of them survive from great geological antiquity. +They present from age to age diversity of aspect and habit, and in +unexpected differences of outward proportion of the body show how the +laws of life have preserved each animal type. For the vital organs which +constitute each animal a reptile, and the distinctive bony structures +with which they are associated, remain unaffected, or but little +modified, by the animal's external change in appearance. + +The creeping reptile is commonly imagined as the antithesis of the bird. +For the bird overcomes the forces that hold even man to the earth, and +enjoys exalted aerial conditions of life. Therefore the marvel is shared +equally by learned and unlearned, that the power of flight should have +been an endowment of animals sprung from the breed of serpents, or +crocodiles, enabling them to move through the air as though they too +were of a heaven-born race. The wonder would not be lessened if the +animal were a degraded representative of a nobler type, or if it should +be demonstrated that even beasts have advanced in the battle of life. +The winged reptile, when compared with a bird, is not less astounding +than the poetic conceptions in Milton's _Paradise Lost_ of degradation +which overtakes life that once was amongst the highest. And on the other +hand, from the point of view of the teaching of Darwin in the theories +of modern science, we are led to ask whether a flying reptile may not be +evidence of the physical exaltation which raises animals in the scale of +organisation. The dominance upon the earth of flying reptiles during the +great middle period of geological history will long engage the interest +of those who can realise the complexity of its structure, or care to +unravel the meaning of the procession of animal forms in successive +geological ages which preceded the coming of man. + +The outer vesture of an animal counts for little in estimating the value +of ties which bind orders of animals together, which are included in the +larger classes of life. The kindred relationship which makes the snake +of the same class as the tortoise is determined by the soft vital +organs--brain, heart, lungs--which are the essentials of an animal's +existence and control its way of life. The wonder which science weaves +into the meaning of the word "reptile," "bird," or "mammal," is partly +in exhibiting minor changes of character in those organs and other soft +parts, but far more in showing that while they endure unchanged, the +hard parts of the skeleton are modified in many ways. For the bones of +the reptile orders stretch their affinities in one direction towards the +skeletons of salamanders and fishes; and extend them also at the same +time in other directions, towards birds and mammals. This mystery we may +hope to partly unravel. + + + + +CHAPTER II + +HOW A REPTILE IS KNOWN + + +DEFINITION OF REPTILES BY THEIR VITAL ORGANS + +The relations of reptiles to other animals may be stated so as to make +evident the characters and affinities which bind them together. Early in +the nineteenth century naturalists included with the Reptilia the tribe +of salamanders and frogs which are named Amphibia. The two groups have +been separated from each other because the young of Amphibia pass +through a tadpole stage of development. They then breathe by gills, like +fishes, taking oxygen from the air which is suspended in water, before +lungs are acquired which afterwards enable the animals to take oxygen +directly from the air. The amphibian sometimes sheds the gills, and +leaves the water to live on land. Sometimes gills and lungs are retained +through life in the same individual. This amphibian condition of lung +and gill being present at the same time is paralleled by a few fishes +which still exist, like the Australian _Ceratodus_, the lung-fish, an +ancient type of fish which belongs to early days in geological time. + +This metamorphosis has been held to separate the amphibian type from +the reptile because no existing reptile develops gills or undergoes a +metamorphosis. Yet the character may not be more important as a ground +for classification than the community of gills and lungs in the fish and +amphibian is ground for putting them together in one natural group. For +although no gills are found in reptiles, birds, or mammals, the embryo +of each in an early stage of development appears to possess gill-arches, +and gill-clefts between them, through which gills might have been +developed, even in the higher vertebrates, if the conditions of life had +been favourable to such modification of structure. In their bones +Reptiles and Amphibia have much in common. Nearly all true reptiles lay +eggs, which are defined like those of birds by comparatively large size, +and are contained in shells. This condition is not usual in amphibians +or fishes. When hatched the young reptile is completely formed, the +image of its parent, and has no need to grow a covering to its skin like +some birds, or shed its tail like some tadpoles. The reptile is like the +bird in freedom from important changes of form after the egg is hatched; +and the only structure shed by both is the little horn upon the nose, +with which the embryo breaks the shell and emerges a reptile or a bird, +growing to maturity with small subsequent variations in the proportions +of the body. + + [Illustration: FIG. 1 LUNG OF THE FISH CERATODUS + + Partly laid open to show its chambered structure (After Guenther)] + + +THE REPTILE SKIN + +Between one class of animals and another the differences in the +condition of the skin are more or less distinctive. In a few amphibians +there are some bones in the skin on the under side of the body, though +the skin is usually naked, and in frogs is said to transmit air to the +blood, so as to exercise a respiratory function of a minor kind. This +naked condition, so unlike the armoured skin of the true Reptilia, +appears to have been paralleled by a number of extinct groups of fossils +of the Secondary rocks, such as Ichthyosaurs and Plesiosaurs, which were +aquatic, and probably also by some Dinosauria, which were terrestrial. + +Living reptiles are usually defended with some kind of protection to the +skin. Among snakes and lizards the skin has commonly a covering of +overlapping scales, usually of horny or bony texture. The tortoise and +turtle tribe shut up the animal in a true box of bone, which is cased +with an armour of horny plates. Crocodiles have a thick skin embedding a +less continuous coat of mail. Thus the skin of a reptile does not at +first suggest anything which might become an organ of flight; and its +dermal appendages, or scales, may seem further removed from the feathers +which ensure flying powers to the bird than from the naked skin of a +frog. + + +THE REPTILE BRAIN + +Although the mode of development of the young and the covering of the +skin are conspicuous among important characters by which animals are +classified, the brain is an organ of some importance, although of +greater weight in the higher Vertebrata than in its lower groups. +Reptiles have links in the mode of arrangement of the parts of their +brains with fishes and amphibians. The regions of that organ are +commonly arranged in pairs of nervous masses, known as (1) the olfactory +lobes, (2) the cerebrum, behind which is the minute pineal body, +followed by (3) the pair of optic lobes, and hindermost of all (4) the +single mass termed the cerebellum. These parts of the brain are extended +in longitudinal order, one behind the other in all three groups. The +olfactory lobes of the brain in Fishes may be as large as the cerebrum; +but among Reptiles and Amphibians they are relatively smaller, and they +assume more of the condition found in mammals like the Hare or Mole, +being altogether subordinate in size. And the cerebral masses begin to +be wider and higher than the other parts of the brain, though they do +not extend forward above the olfactory lobes, as is often seen in +Mammals. In Crocodiles the cerebral hemispheres have a tendency to a +broad circular form. Among Chelonian reptiles that region of the brain +is more remarkable for height. Lizards and Ophidians both have this part +of the brain somewhat pear-shaped, pointed in front, and elongated. The +amphibian brain only differs from the lizard type in degree; and +differences between lizards' and amphibian brains are less noticeable +than between the other orders of reptiles. The reptilian brain is easily +distinguished from that of all other animals by the position and +proportions of its regions (see Fig. 19, p. 53). + +Birds have the parts of the brain formed and arranged in a way that is +equally distinctive. The cerebral lobes are relatively large and convex, +and deserve the descriptive name "hemispheres." They are always smooth, +as among the lower Mammals, and extend backward so as to abut against +the hind brain, termed the cerebellum. This junction is brought about in +a peculiar way. The cerebral hemispheres in a bird do not extend +backward to override the optic lobes, and hide them, as occurs among +adult mammals, but they extend back between the optic lobes, so as to +force them apart and push them aside, downward and backward, till they +extend laterally beyond the junction of the cerebrum with the +cerebellum. The brain of a Bird is never reptilian; but in the young +Mammal the brain has a very reptilian aspect, because both have their +parts primarily arranged in a line. Therefore the brain appears to +determine the boundary between bird and reptile exactly. + + +REPTILIAN BREATHING ORGANS + +The breathing organs of Birds and Reptiles which are associated with +these different types of brain are not quite the same. The Frog has a +cellular lung which, in the details of the minute sacs which branch and +cluster at the terminations of the tubes, is not unlike the condition in +a Mammal. In a mammal respiration is aided by the bellows-like action of +the muscles connected with the ribs, which encase the cavity where the +lungs are placed, and this structure is absent in the Frog and its +allies. The Frog, on the other hand, has to swallow air in much the same +way as man swallows water. The air is similarly grasped by the muscles, +and conveyed by them downward to the lungs. Therefore a Frog keeps its +mouth shut, and the animal dies from want of air if its mouth is open +for a few minutes. + +Crocodiles commonly lie in the sun with their mouths widely open. The +lungs in both Crocodiles and Turtles are moderately dense, traversed by +great bronchial tubes, but do not differ essentially in plan from those +of a Frog, though the great branches of the bronchial tubes are +stronger, and the air chambers into which the lung is divided are +somewhat smaller. The New Zealand Hatteria has the lungs of this +cellular type, though rather resembling the amphibian than the +Crocodile. The lungs during life in all these animals attain +considerable size, the maximum dimensions being found in the terrestrial +tortoises, which owe much of their elevated bulk to the dimensions of +the air cells which form the lungs. + +The lungs of Serpents and Lizards are formed on a different plan. In +both those groups of reptiles the dense cellular tissue is limited to +the part of the lung which is nearest to the throat. This network of +blood vessels and air cells extends about the principal bronchial tube +much as in other animals, but as it extends backward the blood vessels +become few until the _tubular_ lung appears in its hinder part, as it +extends down the body, almost as simple in structure as the air bladder +of a fish. Among Serpents only one of these tubular lungs is commonly +present, and the structure has a less efficient appearance as a +breathing organ than the single lung of the fish _Ceratodus_ (Fig. 1). +The Chameleons are a group of lizards which differ in many ways from +most of their nearest kindred, and the lungs, while conforming in +general plan to the lizard type in being dense at the throat, and a +tubular bladder in the body, give off on both sides a number of short +lateral branches like the fingers of a glove (Fig. 18, p. 51). + +Thus the breathing organs of reptiles present two or three distinct +types which have caused Serpents and Lizards to be associated in one +group by most naturalists who have studied their anatomy; while +Crocodiles and Chelonians represent a type of lung which is quite +different, and in those groups has much in common. These characters of +the breathing organs contribute to separate the cold-blooded armoured +reptiles from the warm-blooded birds clothed with feathers, as well as +from the warm-blooded mammals which suckle their young; for both these +higher groups have denser and more elastic spongy lung tissue. + +It will be seen hereafter that many birds in the most active development +of their breathing organs substantially revert to the condition of the +Serpent or Chameleon in a somewhat modified way. Because, instead of +having one great bronchial tube expanded to form a vast reservoir of air +which can be discharged from the lung in which the reptile has +accumulated it, the bird has the lateral branches of the bronchial tubes +prolonged so as to pierce the walls of the lung, when its covering +membrane expands to form many air cells, which fill much of the cavity +of the bird's body (see Fig. 16). Thus the bird appears to combine the +characters of such a lung as that of a Crocodile, with a condition which +has some analogy with the lung of a Chameleon. It is this link of +structure of the breathing organs between reptiles and birds that +constitutes one of the chief interests of flying reptiles, for they +prove to have possessed air cells prolonged from the lungs, which +extended into the bones. + + + + +CHAPTER III + +A REPTILE IS KNOWN BY ITS BONES + + +Such are a few illustrations of ways in which reptiles resemble other +animals, and differ from them, in the organs by means of which the +classification of animals is made. But such an idea is incomplete +without noticing that the bony framework of the body associated with +such vital organs also shows in its chief parts that reptiles are easily +recognised by their bones. I will therefore briefly state how reptiles +are defined in some regions of the skeleton, for in tracing the history +of reptile life the bones are the principal remains of animals preserved +in the rocks; and the soft organs which have perished can only be +inferred to have been present from the persistence of durable +characteristic parts of the skeleton, which are associated with those +soft organs in animals which exist at the present day, and are unknown +in other animals in which the skeleton is different. + + +THE HANG OF THE LOWER JAW + +The manner in which the lower jaw is connected with the skull yields one +of the most easily recognised differences between the great groups of +vertebrate animals. + +_In Mammals._--In every mammal--such as the Dog or Sheep--the lower jaw, +which is formed of one bone on each side, joins directly on to the head +of the animal, and moves upon a bone of the skull which is named the +temporal bone. This character is sufficient to prove, by the law of +association of soft and hard parts of the body, that such an animal had +warm blood and suckled its young. + + [Illustration: FIG. 2 _PTERODACTYLUS KOCHI_ SKULL OF BEAR + + Comparison to show the articulation with the lower jaw in a mammal + and _Pterodactylus Kochi_. The quadrate bone is lettered Q in this + Pterodactyle, and comes between the skull and the lower jaw like the + quadrate bone in a bird and in lizards.] + +_In Birds._--In birds a great difference is found in this region of the +head. The temporal bone, which it will be more convenient to name the +squamosal bone, from its squamous or scale-like form, is still a part of +the brain case, and assists in covering the brain itself, exactly as +among mammals. But the lower jaw is now made up of five or six bones. +And between the hindermost and the squamosal there is an intervening bar +of bone, unknown among mammalia, which moves upon the skull by a joint, +just as the lower jaw moves upon it. This movable bone unites with parts +of the palate and the face, and is known as the quadrate bone. Its +presence proves that the animal possessing it laid eggs, and if the +face bones join its outer border just above the lower jaw, it proves +that the animal possessed hot blood. + +_In Reptiles._--All reptiles are also regarded as possessing the +quadrate bone. But the squamosal bone with which it always unites is in +less close union with the brain case, and never covers the brain itself. +Serpents show an extreme divergence in this condition from birds, for +the squamosal bone appears to be a loose external plate of bone which +rests upon the compact brain case and gives attachment to the quadrate +bone which is as free as in a bird. Among Lizards the quadrate bone is +usually almost as free. In the other division of existing Reptilia, +including Crocodiles, the New Zealand lizard-like reptile Hatteria, +called Tuatera, and Turtles, the squamosal and quadrate bones are firmly +united with the bones of the brain case, face, and palate, so that the +quadrate bone has no movement; and the same condition appears in +amphibians, such as Toads and Frogs. With these conditions of the +quadrate bone are associated cold blood, terrestrial life, and young +developed from eggs. + +_In Fishes._--Bony fishes, and all others in which separate bones build +up the skull, differ from Reptiles and Birds much as those animals +differ from Mammals. The union of the lower jaw with the skull becomes +complicated by the presence of additional bones. The quadrate bone still +forms a pulley articulation upon which the lower jaw works, but between +it and the squamosal bone is the characteristic bone of the fish known +as the hyomandibular, commonly connected with opercular bones and +metapterygoid which intervene, and help to unite the quadrate with the +brain case. In the Cartilaginous fishes there is only one bone +connecting the jaws with the skull on each side. This appears to prove +that just as the structure of the arch of bones suspending the jaw may +be complicated by the mysterious process called segmentation, which +separates a bone into portions, so simplification and variation may +result because the primitive divisions of the material cease to be made +which exists before bones are formed. + +The principal regions of the skull and skeleton all vary in the chief +groups of animals with backbones; so that the Reptile may be recognised +among fossils, even in extinct groups of animals and occasionally +restored from a fragment, to the aspect which characterised it while it +lived. + + + + +CHAPTER IV + +ANIMALS WHICH FLY + + +The nature of a reptile is now sufficiently intelligible for something +to be said concerning flight, and structures by means of which some +animals lift themselves in the air. It is not without interest to +remember that, from the earliest periods in human records, +representations have been made of animals which were furnished with +wings, yet walked upon four feet, and in their typical aspect have the +head shaped like that of a bird. They are commonly named Dragons. + + +FLYING DRAGONS + + [Illustration: FIG. 3 From _The Battle between Bel and the Dragon_] + +The effigy of the dragon survives to the present day in the figure over +which St. George triumphs, on the reverse of the British sovereign. In +the luxuriant imaginations of ancient Eastern peoples, dating back to +prehistoric ages, perhaps 5000 B.C., the dragons present an astonishing +constancy of form. In after-times they underwent a curious evolution, as +the conception of Babylon and Egypt is traced through Assyria to Greece. +The Wings, which had been associated at first with the fore limb of the +typical dragon, become characteristic of the Lion, and of the poet's +winged Horse, and finally of the Human figure itself, carved on the +great columns of the Greek temples of Ephesus. These flying animals are +historically descendants of the same common stock with the dragons of +China and Japan, which still preserve the aspect of reptiles. Their +interest is chiefly in evidence of a latent spirit of evolution in days +too remote for its meaning to be now understood, which has carried the +winged forms higher and ever higher in grade of organisation, till their +wings ceased to be associated with feelings of terror. The Hebrew +cherubim are regarded by H. E. Ryle, Bishop of Exeter, as probably +Dragons, and the figure of the conventional angel is the human form of +the Dragon. + + [Illustration: FIG. 4. FIGURE FROM THE TEMPLE OF EPHESUS] + + +ORGANS OF FLIGHT + +Turning from this reference to the realm of mythology to existing +nature, the power of flight is popularly associated with all the chief +types of vertebrate animals--fishes, frogs, lizards, birds, and mammals. +Many of the animals ill deserve the name of flyers, and most are +exceptions to different conditions of existence which control their +kindred, but it is convenient to examine for a little the nature of the +structures by which this movement in the air, which is not always +flight, is made possible. Certain fishes, like the lung-fish Ceratodus, +of Queensland, and the mud-fish Lepidosiren, are capable of leaving the +water and living on land, and for a time breathe air. But neither these +fishes nor Periophthalmus, which runs with rapid movement of its fins +and carries the body more or less out of water, or the climbing perch, +Anabas, carried out of water over the country by Indian jugglers, ever +put on the slightest approach to wings. + + +FLYING FISHES + + [Illustration: FIG. 5. THE FLYING FISH EXOCOETUS + + With the fins extended moving through the air] + +The flight of fishes is a kind of parachute support not unlike that by +which a folded paper is made to travel in the air. It is chiefly seen in +the numerous species of a genus Exocoetus, allied to the gar-pike +(Belone), which is common in tropical seas, and usually from a foot to +eighteen inches long. They emerge from the water, and for a time support +themselves in the air by means of the greatly developed breast fins, +which sometimes extend backward to the tail fin. Although these fins +appear to correspond to the fore limbs of other animals, they may not be +moved at the will of the fish like the wing of a bird. When the flying +fishes are seen in shoals in the vicinity of ships, those fins remain +extended, so that the fish is said sometimes to travel 200 yards at a +speed of fifteen miles an hour, rising twenty feet or more above the +surface of the sea, travelling in a straight line, though sometimes +influenced by the wind. Here the organ, which is at once a fin and a +wing, consists of a number of thin long rods, or rays, which are +connected by membrane, and vary in length to form an outline not unlike +the wing of a bird which tapers to a point. The interest of these +animals is chiefly in the fact that flight is separated from the +condition of having lungs with which it is associated in birds, for +although the flying fish has an air bladder, there is no duct to connect +it with the throat. + + +FLYING FROGS + + [Illustration: FIG. 6. THE FLYING FROG (RHACOPHORUS) + + The membranes of the foot and hand extend between the metatarsal and + metacarpal bones, as well as the bones of the digits.] + +Among amphibians the organs of flight are also of a parachute kind, but +of a different nature. They are seen in certain frogs which frequent +trees, and are limited to membranes which extend between the diverging +digits of the hand and foot, forming webs as fully developed as in the +foot of a swimming bird. As these frogs leap, the membranes are expanded +and help to support the weight of the body, so that the animal descends +more easily as it moves from branch to branch. There is no evidence that +the bones of the digits ever became elongated like the fin rays of the +flying fish or the wing bones of a Bat; but the web suggests the basis +of such a wing, and the possibilities under which wings may first +originate, by elongation of the bones of a webbed hand like that of a +Flying Frog. + + +FLYING LIZARDS + + [Illustration: FIG. 7. THE FLYING DRAGON, DRACO + + Forming a parachute by means of the extended ribs] + +The Reptilia in their several orders are remarkable for absence of any +modification of the arms which might suggest a capacity for acquiring +wings, as being latent in their organisation. Crocodiles, Tortoises, and +Serpents are alike of the earth, and not of the air. But among Lizards +there are small groups of animals in which a limited capacity for +movement through the air is developed. It is best known in the family of +small lizards named Dragons, represented typically by the species _Draco +volans_ found in the Oriental region of the East Indies and Malay +Archipelago. + +The organ of flight is produced in an unexpected way, by means of the +ribs instead of the limbs. The ribs extend outward as far as the arms +can stretch, and the first five or six are prolonged beyond the body so +as to spread a fold of skin on each side between the arm and the leg. +The membrane admits of some movement with the ribs. This arrangement +forms a parachute, which enables the animal to move rapidly among +branches of trees, extending the structure at will, so that it is used +with rapidity too quick to be followed by the eye, as it leaps through +considerable distances. + +A less singular aid to movement in the air is found in some of the +lizards termed Geckos. The so-called Flying Gecko (_Platydactylus +homalocephalus_) has a fringe unconnected with ribs, which extends +laterally on the sides of the body and tail, as well as at the back and +front of the fore and hind limbs, and between the digits, where the web +is sometimes almost as well developed as among Tree Frogs. This is +essentially a lateral horizontal frill, extending round the body. Its +chief interest is in the circumstance that it includes a membrane which +extends between the wrist bones and the shoulder on the front of the +arm. That is the only part of the fringe which represents the wing +membrane of a bird. The fossil flying reptiles have not only that +membrane, but the lateral membranes at the sides of the body and behind +the arms. + +Other lizards have the skin developed in the direction of the +circumference of the body. In the Australian Chlamydosaurus it forms an +immense frill round the neck like a mediaeval collar. But though such an +adornment might break a fall, it could not be regarded as an organ of +flight. + + +FLYING BIRDS + + [Illustration: FIG. 8. POSITION OF BIRDS IN FLIGHT] + +The wings of birds, when they are developed so as to minister to flight, +are all made upon one plan; but as examples of the variation which the +organs contributing to make the fore limb manifest, I may instance the +short swimming limb of the Penguin, the practically useless rudiment of +a wing found in the Ostrich or Kiwi, and the fully developed wing of the +Pigeon. The wings of birds obtain an extensive surface to support the +animal by muscular movements of three modifications of structure. First, +the bones of the fore limb are so shaped that they cannot, in existing +birds, be applied to the ground for support and be used like the limbs +of quadrupeds, and are therefore folded up at the sides of the body, +and carried in an unused or useless state so long as the animal hops on +the ground or walks, balancing its weight on the hind legs. Secondly, +there are two small folds of skin, less conspicuous than those on the +arms of Geckos; one is between the wrist bones and the shoulder, and the +smaller hinder membrane is between the upper arm and the body. These +membranous expansions are insignificant, and would in themselves be +inadequate to support the body or materially assist its movements. +Thirdly, the bird develops appendages to the skin which are familiarly +known as feathers, and the large feathers which make the wing are +attached to the skin covering the lower arm bone named the ulna, and the +other bones which represent the wrist and hand. The area and form of the +bird's wing are due to individual appendages to the skin, which are +unknown in any other group of animals. Between the extended wing of the +Albatross, measuring eleven feet in spread, and the condition in the +Kiwi of New Zealand, in which the wing is vanishing, there is every +possible variation in size and form. As a rule, the larger the animal +the smaller is the wing area. The problem of the origin of the bird's +wing is not to be explained by study of existing animals; for the rowing +organ of the Penguin, which in itself would never suggest flight, +becomes an organ of flight in other birds by the growth upon it of +suitable feathers. Anyone who has seen the birds named Divers feeding +under water, swimming rapidly with their wings, might never suspect that +they were also organs of aerial flight. The Ostrich is even more +interesting, for it has not developed flight, and still retains at the +extremities of two of the digits the slender claws of a limb which was +originally no wing at all, but the support of a four-footed animal (Fig. +46, p. 130). + + +FLYING MAMMALS + +Flight is also developed among mammals. The Insectivora include several +interesting examples of animals which are capable of a certain motion +through the air. In the tropical forests of the Malay Archipelago are +animals known as Flying Squirrels, Flying Opossums, Flying Lemurs, +Flying Foxes, in which the skin extends outward laterally from the sides +of the body so as to connect the fore limbs with the hind limbs, and is +also prolonged backward from the hind limbs to the tail. The four digits +are never elongated; the bones of the fore limb are neither longer nor +larger than those of the hind limb, and the foot terminates in five +little claws as in other four-footed animals. This condition is adapted +for the arboreal life which those animals live, leaping from branch to +branch, feeding on fruits and leaves, and in some cases upon insects. +These mammals may be compared with the Flying Geckos among reptiles in +their parachute-like support by extension of the skin, which gives them +one of the conditions of support which contribute to constitute flight. + + [Illustration: FIG. 9. FLYING SQUIRREL (PTEROMYS)] + +_Bats._--One entire order of mammals--the Bats--not only possess true +wings, but are capable of flight which is sustained, and in some cases +powerful. The wings are clothed with short hair like the rest of the +body, and thus the instrument of flight is unlike that of a bird. The +flight of a Bat differs from that of all other animals in being +dependent upon a modification of the bones of the fore limb, which, +without interfering with the animal's movements as a quadruped, secures +an extension of the wing which is not inferior in area to that which the +bird obtains by elongation of the bones of the arm and fore-arm and its +feathers. The distinctive peculiarity of the Bat's wing is in the +circumstance that four of the digits of the hand have their bones +prolonged to a length which is often equal to the combined length of the +arm and fore-arm. The bones of the digits diverge like the ribs of an +umbrella, and between them is the wing membrane, which extends from the +sides of the body outward, unites the fore limb with the hind limb, and +is prolonged down the tail as in the Flying Foxes. Bats have a small +membrane in front of the bones of the arm and fore-arm stretching +between the shoulder and the wrist, which corresponds with the wing +membrane of a bird; but the remainder of the membranes in Bats' wings +are absent in birds, because their function is performed by feathers +which give the wing its area. The elongated digits of the Bat's wing are +folded together and carried at the sides of the body as though they were +a few quill pens attached to its wrist, where the one digit, which is +applied to the ground in walking, terminates in a claw. + + [Illustration: FIG. 10 NEW ZEALAND BAT FLYING. BARBASTELLE WALKING] + +The organs which support animals in the air are thus seen to be more or +less dissimilar in each of the great groups of animals. They fall into +three chief types: first, the parachute; secondly, the wing due to the +feathers appended to the skin; and thirdly, the wing formed of membrane, +supported by enormous elongation of the small bones of the back of the +hand and fingers. The two types of true wings are limited to birds and +bats; and no living reptile approximates to developing such an organ of +flight as a wing. Judged, therefore, by the method of comparing the +anatomical structures of one animal with another, which is termed +"comparative anatomy," the existence of flying reptiles might be +pronounced impossible. But in the light which the revelations of geology +afford, our convictions become tempered with modesty; and we learn that +with Nature nothing is impossible in development of animal structure. + + + + +CHAPTER V + +DISCOVERY OF THE PTERODACTYLE + + +Late in the eighteenth century, in 1784, a small fossil animal with +wings began to be known through the writings of Collini, as found in the +white lithographic limestone of Solenhofen in Bavaria, and was regarded +by him as a former inhabitant of the sea. The foremost naturalist of the +time, the citizen Cuvier--for it was in the days of the French +Republic--in 1801, in lucid language, interpreted the animal as a genus +of Saurians. That word, so familiar at the present day, was used in the +first half of the century to include Lizards and Crocodiles; and +described animals akin to reptiles which were manifestly related neither +to Serpents nor Turtles. But the term saurian is no longer in favour, +and has faded from science, and is interesting only in ancient history +of progress. The lizards soon became classed in close alliance with +snakes. And the crocodiles, with the Hatteria, were united with +chelonians. Most modern naturalists who use the term saurian still make +it an equivalent of lizard, or an animal of the lizard kind. + + +CUVIER + + [Illustration: FIG. 11. _PTERODACTYLUS LONGIROSTRIS_ (Cuvier) + + The remains are preserved with the neck arched over the back, and the + jaws opened upward] + +Cuvier defined this fossil from Solenhofen as distinguished by the +extreme elongation of the fourth digit of the hand, and from that +character invented for the animal the name Pterodactyle. He tells us +that its flight was not due to prolongation of the ribs, as among the +living lizards named Dragons; or to a wing formed without the digits +being distinguishable from each other, as among Birds; nor with only one +digit free from the wing, as among Bats; but by having the wing +supported mainly by a single greatly elongated digit, while all the +others are short and terminate in claws. Cuvier described the amazing +animal in detail, part by part; and such has been the influence of his +clear words and fame as a great anatomist that nearly every writer in +after-years, in French and in English, repeated Cuvier's conclusion, +maintained to the end, that the animal is a saurian. + + [Illustration: FIG. 12. THE SKELETON OF _PTERODACTYLUS LONGIROSTRIS_ + + Reconstructed from the scattered bones in Fig. 14, showing the limbs + on the left side] + +Long before fashion determined, as an article of educated belief, that +fossil animals exist chiefly to bridge over the gaps between those which +still survive, the scientific men of Germany were inclined to see in the +Pterodactyle such an intermediate type of life. At first Soemmerring and +Wagler would have placed the Pterodactyle between mammals and birds. + + +GOLDFUSS + + [Illustration: FIG. 13. THE _PTERODACTYLUS LONGIROSTRIS_ RESTORED + FROM THE REMAINS IN FIG. 11 + + Showing positions of the wing membranes with the animal at rest] + +But the accomplished naturalist Goldfuss, who described another fine +skeleton of a Pterodactyle in 1831, saw in this flying animal an +indication of the course taken by Nature in changing the reptilian +organisation to that of birds and mammals. It is the first flash of +light on a dark problem, and its brilliance of inference has never been +equalled. Its effects were seen when Prince Charles Bonaparte, the +eminent ornithologist, in Italy, suggested for the group the name +Ornithosauria; when the profound anatomist de Blainville, in France, +placed the short-tailed animal in a class between Reptiles and Birds +named Pterodactylia; and Andreas Wagner, of Munich, who had more +Pterodactyles to judge from than his predecessors, saw in the fossil +animal a saurian in transition to a bird. + + +VON MEYER + +But the German interpretation is not uniform, and Hermann von Meyer, the +banker-naturalist of Frankfurt a./M., who made himself conversant with +all that his predecessors knew, and enlarged knowledge of the +Pterodactyles on the most critical facts of structure, continued to +regard them as true reptiles, but flying reptiles. Such is the influence +of von Meyer that all parts of the world have shown a disposition to +reflect his opinions, especially as they practically coincide with the +earlier teaching of Cuvier. Owen and Huxley in England, Cope and Marsh +in America, Gaudry in France, and Zittel in Germany have all placed the +Pterodactyles as flying reptiles. Their judgment is emphatic. But there +is weight of competent opinion to endorse the evolutionary teaching of +Goldfuss that they rise above reptiles. To form an independent opinion +the modern student must examine the animals, weigh their characters bone +by bone, familiarise himself, if possible, with some of the rocks in +which they are found; to comprehend the conditions under which the +fossils are preserved, which have added not a little to the interest in +Pterodactyles, and to the difficulty of interpretation. + + +GEOLOGICAL HISTORY OF PTERODACTYLES IN GERMANY + +We may briefly recapitulate the geological history. Those remains of +Ornithosaurs which have been mentioned, with a multitude of others which +are the glory of the museums of Munich, Stuttgart, Tuebingen, +Heidelberg, Bonn, Haarlem, and London, have all been found in working +the lithographic stone of Bavaria. The whitish yellow limestone forms +low, flat-topped hills, now isolated from each other by natural +denudation, which has removed the intervening rock. The stone is found +at some distance north of the Danube, in a line due north of Augsburg, +in the country about Pappenheim, and especially at the villages of +Solenhofen, Eichstaedt, Kelheim, and Nusplingen. These beds belong to the +rocks which are named White Jura limestone in Germany, which is of about +the same geological age as the Kimeridge clay in England. Much of it +divides into very thin layers, and in these planes of separation the +fossils are found. They include the _Ammonites lithographicus_ and a +multitude of marine shells, king crabs and other Crustacea, sea-urchins, +and other fossils, showing that the deposit was formed in the sea. The +preservation of jelly-fish, which so soon disappear when left dry on the +beach, shows that the ancient calcareous mud had unusual power of +preserving fossils. Into this sea, with its fishes great and small, came +land plants from off the land, dragonflies and other insects, tortoises +and lizards, Pterodactyles with their flying organs, and birds still +clothed with feathers. Sometimes the wing membranes of the flying +reptiles are found fully stretched by the wing finger, as in examples to +be seen at Munich and in the Yale Museum in Newhaven, in America. At +Haarlem there is an example in which the wing membrane appears to be +folded much as in the wing of a Bat, when the animal hangs suspended, +with the flying membrane bent into a few wide undulations. + +The Solenhofen Slate belongs to about the middle period of the history +of flying reptiles, for they range through the Secondary epochs of +geological time. Remains are recorded in Germany from the Keuper beds at +the top of the Trias, which is the bottom division of the Secondary +strata; and I believe I have seen fragments of their bones from the +somewhat older Muschelkalk of Germany. + + +THEIR HISTORY IN ENGLAND + +In England the remains are found for the first time in the Lower Lias of +Lyme Regis, in Dorset, and the Upper Lias of Whitby, in Yorkshire. In +Wuertemberg they occur on the same horizons. They reappear in England, in +every subsequent age, when the conditions of the strata and their +fossils give evidence of near proximity to land. In the Stonesfield +Slate of Stonesfield, in Oxfordshire, the bones are found isolated, but +indicate animals of some size, though not so large as the rare bones of +reputed true birds which appear to have left their remains in the same +deposit. + +At least two Pterodactyles are found in the Oxford clay, known from more +or less fragmentary remains or isolated bones; just as they occur in the +Kimeridge Clay, Purbeck Limestone, Wealden sandstones, and especially in +newer Secondary rocks, named Gault, Upper Greensand, and Chalk, in the +south-east of England. + +Owing to exceptional facilities for collecting, in consequence of the +Cambridge Greensand being excavated for the valuable mineral phosphate +of lime it contains, more than a thousand bones are preserved, more or +less broken and battered, in the Woodwardian Museum of the University +of Cambridge alone. To give some idea of their abundance, it may be +stated that they were mostly gathered during two or three years, as a +matter of business, by an intelligent foreman of washers of the nodules +of phosphate of lime, which, in commerce, are named coprolites. He soon +learned to distinguish Pterodactyle bones from other fossils by their +texture, and learned the anatomical names of bones from specimens in the +University Museum. This workman, Mr. Pond, employed by Mr. William +Farren, brought together not only the best of the remains at Cambridge, +but most of those in the museums at York and in London, and the +thousands of less perfect specimens in public and private collections +which passed through the present writer's hands in endeavours to secure +for the University useful illustrations of the animal's structure. These +fragments, among which there are few entire bones, are valuable, for +they have afforded opportunities of examining the articular ends of +bones in every aspect, which is not possible when similar organic +remains are embedded in rock in their natural connexions. + +In England Flying Reptiles disappear with the Chalk. In that period they +were widely distributed, being found in Bohemia, in Brazil, and Kansas +in the United States, as well as in Kent and other parts of England. +They attained their largest dimensions in this period of geological +time. One imperfect fragment of a bone from the Laramie rocks of Canada +was described, I believe, by Cope, though not identified by him as +Ornithosaurian, and is probably newer than other remains. + + +ASPECT OF PTERODACTYLES + +If this series of animals could all be brought together they would vary +greatly in aspect and stature, as well as in structure. Some have the +head enormously long, in others it is large and deep, characters which +are shared by extinct reptiles which do not fly, and to which some birds +may approximate; while in a few the head is small and compact, no more +conspicuous, relatively, than the head of a Sparrow. The neck may be +slender like that of a Heron, or strong like that of an Eagle; the back +is always short, and the tail may be inconspicuous, or as long as the +back and neck together. These flying reptiles frequently have the +proportions of the limbs similar to those of a Bat, with fore legs +strong and hind legs relatively small; while in some the limbs are as +long, proportionately, and graceful as those of a Deer. With these +differences in proportions of the body are associated great differences +in the relative length of the wing and spread of the wing membranes. + + +DIMENSIONS OF THE ANIMALS + +The dimensions of the animals have probably varied in all periods of +geological time. The smallest, in the Lithographic Slate, are smaller +than Sparrows, while associated with them are others in which the +drumstick bone of the leg is eight inches long. In the Cambridge +Greensand and Chalk imperfect specimens occur, showing that the upper +arm bones are larger than those of an Ox. The shaft is one and a half +inches in diameter and the ends three inches wide. Such remains may +indicate Pterodactyles not inferior in size to the extinct Moas of New +Zealand, but with immensely larger heads, animals far larger than birds +of flight. + +The late Sir Richard Owen, on first seeing these fragmentary remains, +said "the flying reptile with outstretched pinions must have appeared +like the soaring Roc of Arabian romance, but with the features of +leathern wings with crooked claws superinduced, and gaping mouth with +threatening teeth." Eventually we shall obtain more exact ideas of their +aspect, when the structures of the several regions of the body have been +examined. The great dimensions of the stretch of wing, often computed at +twenty feet in the larger examples, might lead to expectations of great +weight of body, if it were not known that an albatross, with wings +spreading eleven feet, only weighs about seventeen pounds. + + + + +CHAPTER VI + +HOW ANIMALS ARE INTERPRETED BY THEIR BONES + + +There is only one safe path which the naturalist may follow who would +tell the story of the meaning and nature of an extinct type of animal +life, and that is to compare it as fully as possible in its several +bones, and as a whole, with other animals, especially with those which +survive. It is easy to fix the place in nature of living animals and +determine their mutual relations to each other, because all the +organs--vital as well as locomotive--are available for comparison. On +such evidence they are grouped together into the large divisions of +Beasts, Birds, and Reptiles; as well as placed in smaller divisions +termed Orders, which are based upon less important modifications of +fundamental structures. All these characteristic organs have usually +disappeared in the fossil. Hence a new method of study of the hard parts +of the skeleton, which alone are preserved, is used in the endeavour to +discover how the Flying Reptile or other extinct animal is to be +classified, and how it acquired its characters or came into existence. + + +VARIATIONS OF BONES AMONG MAMMALIA + + [Illustration: FIG. 14. THE FORE LIMB IN FOUR TYPES OF MAMMALS + + Comparison of the fore limb in mammals, showing variation of form + of the bones with function] + +Resemblances and differences in the bones are easily over-estimated in +importance as evidence of pedigree relationship. The Mammalia show, by +means of such skeletons as are exhibited in any Natural History Museum, +how small is the importance to be attached to even the existence of any +group of bones in determining its grade of organisation. The whole Whale +tribe suckle their young and conform to the distinctive characters in +brain and lungs which mark them as being mammals. But if there is one +part of the skeleton more than another which distinguishes the Mammalia, +it is the girdle of bones at the hips which supports the hind limbs. It +is characterised by the bone named the ilium being uniformly directed +forward. Yet in the Whale tribe the hip-girdle and the hind limb which +it usually supports are so faintly indicated as to be practically lost; +while the fore limb becomes a paddle without distinction of digits, and +is therefore devoid of hoofs or claws, which are usual terminations of +the extremities in mammals. Yet this swimming paddle, with its +ill-defined bones--sometimes astonishing in number, as well as in +fewness of the finger bones--is represented by the burrowing fore limb +of the Mole, which lives underground; by the elongated hoofed legs of +the Giraffe, which lives on plains; and the extended arm and finger +bones of the Bat, which are equally mammals with the Whale. From such +comparison it is seen that no proportion, or form, or length, or use of +the bones of the limbs, or even the presence of limbs, is necessarily +characteristic of a mammal. No limitation can be placed upon the +possible diversity of form or development of bones in unknown animals, +when they are considered in the light of such experience of varied +structural conditions in living members of a single class. + +What is true for the limbs and the bony arches which support them is +true for the backbone also, for the ribs, and to some extent for the +skull. The neck in the Whale is shortened almost beyond recognition. In +the Giraffe the same seven vertebrae are elongated into a marvellous +neck; so that in the technical definition of a mammal both are said to +have seven neck vertebrae. Yet exceptions show a capacity for variation. +One of the Sloths reduces the number to six, while another has nine +vertebrae in the neck; proving that there is no necessary difference +between a mammal and a reptile when judged by a character which is +typically so distinctive of mammals as the number of the neck bones. + +The skull varies too, though to a less extent. The Great Ant-eater of +South America is a mammal absolutely without teeth. The Porpoises have a +simple unvarying row of conical teeth with single roots extending along +the jaw. And the dental armature of the jaws, and relative dimensions of +the skull bones, exhibit such diversity, in evidence of what may be +parted with or acquired, that recognition of the many reptilian +structures and bones in the skull of Ornithorhynchus, the Australian +Duckbill, demonstrates that the difficulties in recognising an animal by +its bones are real, unless we can discover the Animal Type to which the +bones belong; and that there is very little in osteology which may not +be lost without affecting an animal's grade of organisation. + + +VARIATION IN SKIN COVERING OF MAMMALS + +Even the covering of the body varies in the same class, or even order of +animals, so that the familiar growth on the skin is never its only +possible covering. The Indian ant-eater, named Manis, which looks like a +gigantic fir-cone, the Armadillo, which sheathes the body in rings of +bone, bearing only a scanty development of hair, are examples of +mammalian hair, as singular as the quills of a Porcupine, the horn of a +Rhinoceros, or the growth of hair of varying length and stoutness on +different parts of the body in various animals, or the imperfect +development of hair in the marine Cetacea. Among living animals it is +enough for practical purposes to say that a mammal is clothed with hair, +but in a fossil state the hair must usually be lost beyond recognition +from its fineness and shortness of growth. + + +VARIATION IN SKIN COVERING OF BIRDS + +No Class of living animals is more homogeneous than Birds; and +well-preserved remains prove that, at least as far back in time as the +Upper Oolites, birds were clothed with feathers of essentially the same +mode of growth and appearance as the feathers of living birds. There +may, therefore, be no ground for assuming that the covering was ever +different, though some regions of the skin are free from feathers. Yet +the variations from fine under-down to the scale-like feathers on the +wings of a Penguin, or the great feathers in the wings of birds of +flight, or the double quill of the Ostrich group, are calculated to +yield dissimilar impressions in a fossil state, even if the fine down +would be preserved in any stratum. + + +VARIATION IN THE BONES OF BIRDS + +Osteologically there is less variety in the skeleton of birds than in +other great groups of animals. The existing representatives do not +exhaust its capability for modification. The few specimens of birds +hitherto found in the Secondary strata have rudely removed many +differences in the bones which separated living birds from reptiles; so +that if only the older fossil birds were known, and the Tertiary and +living birds had not existed, a bird might have been defined as an +animal having its jaw armed with teeth, instead of devoid of teeth; with +vertebrae cupped at both ends, instead of with a saddle-shaped +articulation which in front is concave from side from side, and convex +from above downwards; in which the bones of the hand are separate, so +that three digits terminating in claws can be applied to the ground, +instead of the metacarpal bones being united in a solid mass with +clawless digits; and in which the tail is elongated like the tail of a +lizard. Yet the limits to variation are not to be formulated till Nature +has exhausted all her resources in efforts to preserve organic types by +adapting them to changed circumstances. Birds may be regarded +theoretically as equally capable with mammals of parting with almost +every distinctive structure in the skeleton by which it is best known. +Even the living frigate bird blends the early joints of the backbone +into a compact mass like a sacrum. The Penguin has a cup-and-ball +articulation in the early dorsal vertebrae, with the ball in front. And +the genus Cypselus has the upper arm bone almost as broad as long, +unlike the bird type. Such examples prove that we are apt to accept the +predominant structures in an animal type as though they were universal, +and forget that inferences based, like those of early investigators, on +limited materials may be re-examined with advantage. + + +VARIATION IN THE BONES OF REPTILES + +The true Reptilia, notwithstanding some strong resemblances to Birds in +technical characters of the skeleton, display among their surviving +representatives an astonishing diversity in the bony framework of the +body, exceeding that of the mammalia. This unlooked-for capacity for +varying the plan of construction of the skeleton is in harmony with the +diversity of structure in groups of extinct animals to which the name +reptiles has also been given. The interval in form is so vast between +Serpent and Tortoise, and so considerable in structure of the skeleton +between these and the several groups of Lizards, Crocodiles, and +Hatteria, that any other diversity could not be more surprising. And the +inference is reasonable that just as mammals live in the air, in the +sea, on the earth, and burrow under the earth, similar modes of +existence might be expected for birds and reptiles, though no bird is +yet known to have put on the aspect of a fish, and no reptiles have been +discovered which roamed in herds like antelopes, or lived in the air +like birds or bats, unless these fossil flying animals prove on +examination to justify the name by which they are known. + +Comparative study of structure in this way demolishes the prejudice, +born of experience of the life which now remains on earth, that the +ideas of Reptile and of Flight are incongruous, and not to be combined +in one animal. The comparative study of the parts of animals does not +leave the student in a chaos of possibilities, but teaches us that +organic structures, which mark the grades of life, have only a limited +scope of change; while Nature flings away every part of the skeleton +which is not vital, or changes its form with altering circumstances of +existence, enforced by revolutions of the Earth's surface in geological +time, in her efforts to save organisms from extinction and pass the +grade of life onward to a later age. + +The bones are only of value to the naturalist as symbols, inherited or +acquired, and vary in value as evidence of the nature and association of +those vital organs which differentiate the great groups of the +vertebrata. + +These distinctive structures, which separate Mammals, Birds, and +Reptiles, are sometimes demonstrated by the impress of their existence +left on the bones; or sometimes they may be inferred from the characters +of the skeleton as a whole. + + + + +CHAPTER VII + +INTERPRETATION OF PTERODACTYLES BY THEIR SOFT PARTS + + +THE ORGANS WHICH FIX AN ANIMAL'S PLACE IN NATURE + +We shall endeavour to ascertain what marks of its grade of organisation +the Pterodactyle has to show. The organs which are capable of modifying +the bones are probably limited to the kidneys, the brain, and the organs +of respiration. It may be sufficient to examine the latter two. + + +PNEUMATIC FORAMINA IN PTERODACTYLES + + [Illustration: FIG. 15. HEAD OF THE HUMERUS OF THE PTERODACTYLE + ORNITHOCHEIRUS + + Showing position of the pneumatic foramen on the ulnar side of the + bone as in a bird] + +Hermann von Meyer, the historian of the Ornithosaurs of the Lithographic +Slate, as early as 1837 described some Pterodactyle bones from the Lias +of Franconia, which showed that air was admitted into the interior of +the bones by apertures near their extremities, which, from this +circumstance, are known as pneumatic foramina. He drew the inference, +naturally enough, that such a structure is absolute proof that the +Pterodactyle was a flying animal. It was not quite the right form in +which the conclusion should have been stated, because the Ostrich and +other birds which do not fly have the principal bones pneumatic. +Afterwards, in 1859, the larger bones which Professor Sedgwick, of +Cambridge, transmitted to Sir Richard Owen established this condition as +characteristic of the Flying Reptiles of the Cambridge Greensand. It was +thus found as a distinctive structure of the bones both at the beginning +and the close of the geological history of these animals. Von Meyer +remarks that the supposition readily follows that in the respiratory +process there was some similarity between Pterodactyles and Birds. This +cautious statement may perhaps be due to the circumstance that in many +animals air cavities are developed in the skull without being connected +with organs of respiration. It is well known that the bulk of the +Elephant's head is due to the brain cavity being protected with an +envelope formed of large air cells. Small air cells are seen in the +skulls of oxen, pigs, and many other mammals, as well as in the human +forehead. The head of a bird like the Owl owes something of its imposing +appearance to the way in which its mass is enlarged by the dense +covering of air cells in the bones above the brain, like that seen in +some Cretaceous Pterodactyles. Nor are the skulls of Crocodiles or +Tortoises exceptions to the general rule that an animal's head bones may +be pneumatic without implying a pneumatic prolongation of air from the +lungs. The mere presence of air cells without specification of the +region of the skeleton in which they occur is not remarkable. The holes +by which air enters the bones are usually much larger in Pterodactyles +than in Birds, but the entrance to the air cell prolonged into the bones +is the same in form and position in both groups. So far as can be judged +by this character, there is no difference between them. The importance +of the comparison can only be appreciated by examining the bones side by +side. In the upper arm bone of a bird, on what is known as the ulnar +border, near to the shoulder joint, and on the side nearest to it, is +the entrance to the air cell in the humerus. In the Pterodactyle the +corresponding foramen has the same position, form, and size, and is not +one large hole, but a reticulation of small perforations, one beyond +another, exactly such as are seen in the entrance to the air cell in the +bone of a bird, in which the pneumatic character is found. For it is not +every bird of flight which has this pneumatic condition of the bones; +and Dr. Crisp stated that quite a number of birds--the Swallow, Martin, +Snipe, Canary, Wood-wren and Willow-wren, Whinchat, Glossy-starling, +Spotted-fly-catcher, and Black-headed Bunting--have no air in their +bones. And it is well known that in many birds, especially water birds, +it is only the upper bones of the limbs which are pneumatic, while the +smaller bones retain the marrow. + + +LUNGS AND AIR CELLS + + [Illustration: FIG. 16. LUNGS OF THE BIRD APTERYX PARTLY OPENED ON + THE RIGHT-HAND SIDE + + The circles are openings of the bronchial tubes on the surface of the + lung. The notches on the inner edges of the lungs are impressions of + the ribs (After R. Owen)] + + [Illustration: FIG. 17. THE BODY OF AN OSTRICH LAID OPEN TO SHOW THE + AIR CELLS WHICH EXTEND THROUGH ITS LENGTH (After Georges Roche)] + +It may be well to remember that the lungs of a bird are differently +conditioned from those of any other animal. Instead of hanging freely +suspended in the cone-shaped chamber of the thorax formed by the ribs +and sternum, they are firmly fixed on each side, so that the ribs deeply +indent them and hold them in place. The lungs have the usual internal +structure, being made up of branching cells. The chief peculiarity +consists in the way in which the air passes not only into them, but +through them. The air tube of the throat of a bird, unlike that of a +man, has the organ of voice, not at the upper end in the form of a +larynx, but at the lower end, forming what is termed a syrinx. There is +no evidence of this in a fossil state, although in a few birds the rings +of the trachaea become ossified, and are preserved. But below the syrinx +the trachaea divides into two bronchi, tubes which carry the ringed +character into the lungs for some distance, and these give off branches +termed bronchial tubes, the finer subdivisions from which, in their +clustered minute branching sacs, make up the substance of the lung. +There is nothing exceptional in that. But towards the outer or middle +part of the ventral or under surface of the lungs, four or five rounded +openings are seen on each side. Each of these openings resembles the +entrance of the air cell into a bone, since it displays several smaller +openings which lead to it. Each opening from the lung leads to an air +cell. Those cells may be regarded as the blowing out of the membrane +which covers the lungs into a film which holds air like a mass of soap +bubbles, until the whole cavity of the body of a bird from neck to tail +is occupied by sacculated air cells, commonly ten in number, five on +each side, though two frequently blend at the base of the neck in the +region of the #V#-shaped bone named the clavicle or furculum, popularly +known as the merry-thought. Most people have seen some at least of +these semi-transparent bladder-like air cells beneath the skin in the +abdominal region of a fowl. The cells have names from their positions, +and on each side one is abdominal, two are thoracic, one clavicular, and +one cervical, which last is at the base of the neck. The clavicular and +abdominal air cells are perhaps the most interesting. The air cell +termed clavicular sends a process outward towards the arm, along with +the blood vessels which supply the arm. Thus this air cell, entering the +region of the axilla or arm-pit, enters the upper arm bone usually on +its under side, close to the articular head of the humerus, and in the +same way the air may pass from bone to bone through every bone in the +fore limb. The hind limbs similarly receive air from the abdominal air +cell, which supplies the femur and other bones of the leg, the sacrum, +and the tail. But the joints of the backbone in front of the sacrum +receive their air from the cervical air sac. The air cells are not +limited to the bones, but ramify through the body, and in some cases +extend among the muscles. A bird may be said to breathe not only with +its lungs, but with its whole body. And it is even affirmed that +respiration has been carried on through a broken arm bone when the +throat was closed, and the bird under water. + +Birds differ greatly in the extent to which the aircell system prolonged +from the lungs is developed, some having the air absent from every bone, +while others, like the Swift, are reputed to have air in every bone of +the body. + +Comparison shows that in so far as the bones are the same in Bird and +Ornithosaur, the evidence of the air cells entering them extends to +resemblance, if not coincidence, in every detail. No living group of +animals except birds has pneumatic limb bones, in relation to the lungs; +so that it is reasonable to conclude that the identical structures in +the bones were due to the same cause in both the living and extinct +groups of animals. It is impossible to say that the lungs were identical +in Birds and Pterodactyles, but so far as evidence goes, there is no +ground for supposing them to have been different. + + +THE LUNGS OF REPTILES + + [Illustration: FIG. 18. THE SIDE OF THE BODY OF A CHAMELEON + + Ribs removed to show the sacculate branched form of the lung] + +There is nothing comparable to birds, either in the lungs of living +reptiles or in their relation to the bones. The Chameleon is remarkable +in that the lung is not a simple bladder prolonged through the whole +length of the body cavity, as in a serpent, but it develops a number of +large lateral branches visible when the body is laid open. Except near +the trachaea, where the tissue has the usual density of a lizard lung, +the air cell is scarcely more complicated than the air bladder of a +fish, and does not enter into any bone of the skeleton. And although +many fishes like the Loach have the swim bladder surrounded by bone +connected with the head, it offers no analogy to the pneumatic condition +of the bones in the Pterodactyle. + + +THE FORM OF THE BRAIN CAVITY + + [Illustration: FIG. 19. THE FORM OF THE BRAIN] + +But the identity of the pneumatic foramina in Birds and Flying Reptiles +is not a character which stands by itself as evidence of organisation, +for a mould of the form of the brain case contributes evidence of +another structural condition which throws some light on the nature of +Ornithosaurs. Among many of the lower animals, such as turtles, the +brain does not fill the chamber in the dry skull, in which the same +bones are found as are moulded upon the brain in higher animals. For the +brain case in such reptiles is commonly an envelope of cartilage, as +among certain fishes; and except among serpents, the Ophidia, the bones +do not completely close the reptilian brain case in front. The brain +fills the brain case completely among birds. A mould from its interior +is almost as definite in displaying the several parts of which it is +formed as the actual brain would be. And the chief regions of the brain +in a bird--cerebrum, optic lobes, cerebellum--show singularly little +variation in proportion or position. The essential fact in a bird's +brain, which separates it absolutely from all other animals, is that the +pair of nerve masses known as the optic lobes are thrust out at the +sides, so that the large cerebral hemispheres extend partly over them as +they extend between them to abut against the cerebellum. This remarkable +condition has no parallel among other vertebrate animals. In Fishes, +Amphibians, Reptiles, and Mammals the linear succession of the several +parts of the brain is never departed from; and any appearance of +variation from it among mammals is more apparent than real, for the +linear succession may be seen in the young calf till the cerebral +hemispheres grow upward and lop backward, so as to hide the relatively +small brain masses which correspond to the optic lobes of reptiles, +extending over these corpora-quadrigemina, as they are named, so as to +cover more or less of the mass of the cerebellum. From these conditions +of the brain and skull, it would not be possible to mistake a mould +from the brain case of a bird for that of a reptile, though in some +conditions of preservation it is conceivable that the mould of the brain +of a bird might be distinguished with difficulty from that of the brain +in the lowest mammals. Taken by itself, the avian form of brain in an +animal would be as good evidence that its grade of organisation was that +of a bird as could be offered. + + +THE BRAIN IN SOLENHOFEN PTERODACTYLES + +It happens that moulds of the brain of Pterodactyles, more or less +complete, are met with of all geological ages--Liassic, Oolitic, and +Cretaceous. The Solenhofen Slate is the only deposit in Europe in which +Pterodactyle skulls can be said to be fairly numerous. They commonly +have the bones so thin as to show the form of the upper surface of the +mould of the brain, or the bones have scaled off the mould, or remain in +the counterpart slab of stone, so as to lay bare the shape of the brain +mass. + +In the Museum at Heidelberg a skull of this kind is seen in the +long-tailed genus of Pterodactyles named Rhamphorhynchus. It shows the +large rounded cerebral hemispheres, which extend in front of cerebral +masses of smaller size a little below them in position, which perhaps +are as like the brain of a monotreme mammal as a bird. + +The short-tailed Pterodactylus described by Cuvier has the cerebral +hemispheres very similar to those of a bird, but the relations of the +hinder parts of the brain to each other are less clear. + +The first specimen to show the back of the brain was found by Mr. John +Francis Walker, M.A., in the Cambridge Greensand. I was able to remove +the thick covering of cellular bone which originally extended above it, +and thus expose evidence that in the mutual relations of the fore and +hind parts of the brain bird and ornithosaur were practically identical. +Another Cambridge Greensand skull showed that in the genus +Ornithocheirus the optic lobes of the brain are developed laterally, as +in birds. That skull was isolated and imperfect. But about the same time +the late Rev. W. Fox, of Brixton, in the Isle of Wight, obtained from +Wealden beds another skull, with jaws, teeth, and the principal bones of +the skeleton, which showed that the Wealden Pterodactyle Ornithodesmus +had a similar and bird-like brain. In 1888 Mr. E. T. Newton, F.R.S., +obtained a skull from the Upper Lias, uncrushed and free from +distortion. This made known the natural mould of the brain, which shows +the cerebral hemispheres, optic lobes, and cerebellum more distinctly +than in the specimens previously known. In some respects it recalls the +Heidelberg brain of Rhamphorhynchus in the apparently transverse +subdivision of the optic lobes, but it is unmistakably bird-like, and +quite unlike any reptile. + + +IMPORTANCE OF THE BRAIN AND BREATHING ORGANS + +So far as the evidence goes, it appears that these fossil flying animals +show no substantial differences from birds, either in the mould of the +brain or the impress of the breathing organs upon the bones. These +approximations to birds of the nervous and respiratory systems, which +are beyond question two of the most important of the vital organs of an +animal, and distinctive beyond all others of birds, place the +naturalist in a singular dilemma. He must elect whether he will trust +his interpretation to the soft organs, which among existing animals +never vary their type in the great classes of vertebrate animals, and on +which the animal is defined as something distinct from its envelope the +skeleton and its appendages the limbs, or whether he will ignore them. +The answer must choose substantially between belief that the existing +order of Nature gives warrant for believing that these vital +characteristics which have been discussed might equally coexist with the +skeleton of a mammal or a reptile, as with that of a bird, for which +there is no particle of evidence in existing life. Or, as an +alternative, the fact must be accepted that birds only have such vital +organs as are here found, and therefore the skeleton, that may be +associated with them, cannot affect the reference of the type to the +same division of the animal kingdom as birds. The decision need not be +made without further consideration. But brain and breathing organs of +the avian type are structures of a different order of stability in most +animals from the bones, which vary to a remarkable extent in almost +every ordinal group of animals. + + +TEMPERATURE OF THE BLOOD + +The organs of circulation and digestion are necessarily unknown. There +are reasons why the blood may have been hot, such as the evidences from +the wings of exceptional activity; though the temperature depends more +upon the amount of blood in the body than upon the apparatus by which it +is distributed. We speak of a Crocodile as cold-blooded, yet it is an +animal with a four-chambered heart not incomparable with that of a +bird. On the other hand, the Tunny, a sort of giant Mackerel, is a fish +with a three-chambered heart, only breathing the air dissolved in water, +which has blood as warm as a mammal, its temperature being compared to +that of a pig. Several fishes have blood as warm as that of Manis, the +scaly ant-eater; and many birds have hotter blood than mammals. The term +"hot-blooded," as distinct from "cold-blooded," applied to animals, is +relative to the arbitrary human standard of experience, and expresses no +more than the circumstance that mammals and birds are warmer animals +than reptiles and fishes. + +The exceptional temperature of the Flying Fish has led to a vague +impression that physical activity and its effect upon the amount of +blood which vigour of movement circulates, are more important in raising +an animal's temperature than possession of the circulatory organs +commonly associated with hot blood, which drive the blood in distinct +courses through the body and breathing organs. Yet the kind of heart +which is always associated with vital structures such as Pterodactyles +are inferred to have possessed from the brain mould and the pneumatic +foramina in the bones, is the four-chambered heart of the bird and the +mammal. Considering these organs alone--of which the fossil bones yield +evidence--we might anticipate, by the law of known association of +structures, that nothing distinctly reptilian existed in the other soft +part of the vital organisation, because there is no evidence in favour +of or against such a possibility. + + + + +CHAPTER VIII + +THE PLAN OF THE SKELETON + + +While these animals are incontestably nearer to birds than to any other +animals in their plan of organisation, thus far no proof has been found +that they are birds, or can be included in the same division of +vertebrate life with feathered animals. It is one of the oldest and +soundest teachings of Linnaeus that a bird is known by its feathers; and +the record is a blank as to any covering to the skin in Pterodactyles. +There is the strongest probability against feathers having existed such +as are known in the Archaeopteryx, because every Solenhofen Ornithosaur +appears to have the body devoid of visible or preservable covering, +while the two birds known from the Solenhofen Slate deposit are well +clothed with feathers in perfect preservation. We turn from the skin to +the skeleton. + +The plan on which the skeleton is constructed remains as evidence of the +animal's place in nature, which is capable of affording demonstration on +which absolute reliance would have been placed, if the brain and +pneumatic foramina had remained undiscovered. With the entire skeleton +before us, it is inconceivable that anatomical science should fail to +discover the true nature of the animal to which it belonged, by the +method of comparing one animal with another. There is no lack of this +kind of evidence of Pterodactyles in the three or four scores of +skeletons, and thousands of isolated or associated bones, preserved in +the public museums of Europe and America. + +I may recall the circumstance that the discovery of skeletons of fossil +animals has occasionally followed upon the interpretation of a single +fragment, from which the animal has been well defined, and sometimes +accurately drawn, before it was ever seen. So I propose, before drawing +any conclusions from the skeletons in the entirety of their +construction, to examine them bone by bone, and region by region, for +evidence that will manifest the nature of this brood of Dragons. Their +living kindred, and perhaps their extinct allies, assembled as a jury, +may be able to determine whether resemblances exist between them, and +whether such similarity between the bones as exists is a common +inheritance, or is a common acquisition due to similar ways of life, and +no evidence of the grade of the organism among vertebrate animals. + +The bones of these Ornithosaurs, when found isolated, first have to be +separated from the organisms with which they are associated and mixed in +the geological strata. This discrimination is accomplished in the first +instance by means of the texture of the surface. The density and polish +of the bones is even more marked than in the bones of birds, and is +usually associated with a peculiar thinness of substance of the bone, +which is comparable to the condition in a bird, though usually a little +stouter, so that the bones resist crushing better. Pterodactyle bones +in many instances are recognised by their straightness and comparatively +uniform dimensions, due to the exceptional number of long bones which +enter into the structure of the wing as compared with birds. When the +bones are unerringly determined as Ornithosaurian, they are placed side +by side with all the bones which are most like them, till, judged by the +standard of the structures of living animals, the fossil is found to +show a composite construction as though it were not one animal but many, +while its individual bones often show equally composite characters, as +though parts of the corresponding bone in several animals had been +cunningly fitted together and moulded into shape. + + +THE PLAN OF THE HEAD IN ORNITHOSAURS + +The head is always the most instructive part of an animal. It is less +than an inch long in the small Solenhofen skeleton named _Pterodactylus +brevirostris_, and is said to be three feet nine inches long in the +toothless Pterodactyle Ornithostoma from the Chalk of Kansas. Most of +these animals have a long, slender, conical form of head, tapering to +the point like the beak of a Heron, forming a long triangle when seen +from above or from the side. Sometimes the head is depressed in front, +with the beak flattened or rounded as in a Duck or Goose, and +occasionally in some Wealden and Greensand species the jaws are +truncated in front in a massive snout quite unlike any bird. The back of +the head is sometimes rounded as among birds, showing a smooth +pear-shaped posterior convexity in the region of the brain. Sometimes +the back of the head is square and vertical or oblique. Occasionally a +great crest of cellular tissue is extended backward from above the +brain case over the spines of the neck bones. + +There are always from two to four lateral openings in the skull. First, +the nostril is nearest to the extremity of the beak. Secondly, the +orbits of the eyes are placed far backward. These two openings are +always present. The nostril may incline upward. The orbits of the eyes +are usually lateral, though their upper borders sometimes closely +approximate, as in the woodpecker-like types from the Solenhofen Slate +named _Pterodactylus Kochi_, now separated as another genus. In most +genera there is an opening in the side of the head, between the eye hole +and the nostril, known as the antorbital vacuity; and another opening, +which is variable in size and known as the temporal vacuity, is placed +behind the eye. The former is common in the skulls of birds, the latter +is absent from all birds and found in many reptiles. + +The palate is usually imperfectly seen, but English and American +specimens have shown that it has much in common with the palate in +birds, though it varies greatly in form of the bones in representatives +from the Lias, Oolites, and Cretaceous rocks. + +From the scientific aspect the relative size of the head, its form, and +the positions and dimensions of its apertures and processes, are of +little importance in comparison with its plan of construction, as +evidenced by the positions and relations to each other of the bones of +which it is formed. There usually is some difficulty in stating the +limits of the bones of the skull, because in Pterodactyles, as among +birds, they usually blend together, so that in the adult animal the +sutures between the bones are commonly obliterated. + +Bones have relations to each other and places in the head which can only +change as the organs with which they are associated change their +positions. No matter what the position of a nostril may be--at the +extremity of a long snout, as in an ant-eater, or far back at the top of +the head in a porpoise, or at the side of the head in a bird--it is +always bordered by substantially the same bones, which vary in length +and size with the changing place of the nostril and the form of the +head. Every region of the head is defined by this method of +construction; so that eye holes and nose holes, brain case and jaw +bones, palate and teeth, beak, and back of the skull are all instructive +to those who seek out the life-history of these animals. We may briefly +examine the head of an Ornithosaurian. + + +BONES ABOUT THE NOSTRIL + +No matter what its form may be, the head of an Ornithosaur always +terminates in front in a single bone called the intermaxillary. It sends +a bar of bone backward above the visible nostrils, between them; and a +bar on each side forms the margin of the jaw in which teeth are +implanted. The bone varies in depth, length, sharpness, bluntness, +slenderness, and massiveness. As the bone becomes long the jaw is +compressed from side to side, and the openings of the nostrils are +removed backward to an increasing distance from the extremity of the +beak. + +The outer and hinder border of the nostril is made by another bone named +the maxillary bone, which is usually much shorter than the premaxillary. +It contains the hindermost teeth, which rarely differ from those in +front, except in sometimes being smaller. + +The nasal bones, which always make the upper and hinder border of the +nostrils, meet each other above them, in the middle line of the beak. + + [Illustration: FIG. 20 + + Showing that the extremity of the jaws in Rhamphorhynchus was + sheathed in horn as in the giant Kingfisher, since the jaws + similarly gape in front. + + The hyoid bones are below the lower jaw in the Pterodactyle.] + +The nostrils are unusually large in the Lias genus named Dimorphodon, +and small in species of the genus Rhamphorhynchus from Solenhofen. Such +differences result from the relative dimensions and proportions of these +three bones which margin the nasal vacuity, and by varying growth of +their front margins or of their hinder margins govern the form of the +snout. + +The jaws are most massive in the genera known from the Wealden beds to +the Chalk. The palatal surface is commonly flat or convex, and often +marked by an elevated median ridge which corresponds to a groove in the +lower jaw, though the median ridge sometimes divides the palate into two +parallel concave channels. The jaw is margined with teeth which are +rarely fewer than ten or more than twenty on each side. They are sharp, +compressed from side to side, curved inward, and never have a saw-like +edge on the back and front margins. No teeth occur upon the bones of the +palate. + +In most birds there is a large vacuity in the side of the head between +the nostril and the orbit of the eye, partly separated from it by the +bone which carries the duct for tears named the lachrymal bone. The same +preorbital vacuity is present in all long-tailed Pterodactyles, though +it is either less completely defined or absent in the group with short +tails. It affords excellent distinctive characters for defining the +genera. In the long-tailed genus Scaphognathus from Solenhofen this +preorbital opening is much larger than the nostril, while in Dimorphodon +these vacuities are of about equal size. Rhamphorhynchus is +distinguished by the small size of the antorbital vacuity, which is +placed lower than the nostril on the side of the face. The aperture is +always imperfectly defined in Pterodactylus, and is a relatively small +vacuity compared with the long nostril. In Ptenodracon the antorbital +vacuity appears to have no existence separate from the nostril which +adjoins the eye hole. And so far as is known at present there is no +lateral opening in advance of the eye in the skull in any Ornithosaur +from Cretaceous rocks, though the toothless Ornithostoma is the only +genus with the skull complete. When a separate antorbital vacuity +exists, it is bordered by the maxillary bone in front, and by the malar +bone behind. The prefrontal bone is at its upper angle. That bone is +known in a separate state in reptiles and, I think, in monotreme +mammals. Its identity is soon lost in the mammal, and its function in +the skull is different from the corresponding bone in Pterodactyles. + + +BONES ABOUT THE EYES + + [Illustration: FIG. 21. UPPER SURFACE OF SKULL OF THE HERON + + Compared with the same aspect of the skull of Rhamphorhynchus] + +The third opening in the side of the head, counting from before +backward, is the orbit of the eye. In this vacuity is often seen the +sclerotic circle of overlapping bones formed in the external membrane of +the eye, like those in nocturnal birds and some reptiles. The eye hole +varies in form from an inverted pear-shape to an oblique or transverse +oval, or a nearly circular outline. It is margined by the frontal bone +above; the tear bone or lachrymal, and the malar or cheek bone in front; +while the bones behind appear to be the quadrato-jugal and post-frontal +bones, though the bones about the eye are somewhat differently arranged +in different genera. + +The eyes were frequently, if not always, in contact with the anterior +walls of the brain case, as in many birds, and are always far back in +the side of the head. In Dimorphodon they are in front of the +articulation of the lower jaw; in Rhamphorhynchus, above that +articulation; while in Ornithostoma they are behind the articulation for +the jaw. This change is governed by the position of the quadrate bone, +which is vertical in the Lias genus, inclined obliquely forward in the +fossils from the Oolites, and so much inclined in the Chalk fossil that +the small orbit is thrown relatively further back. + +Thus far the chief difference in the Pterodactyle skull from that of a +bird is in the way in which the malar arch is prolonged backward on each +side. It is a slender bar of bone in birds, without contributing +ascending processes to border vacuities in the side of the face, while +in these fossil animals the lateral openings are partly separated by the +ascending processes of these bones. This divergence from birds, in the +malar bone entering the orbit of the eye is approximated to among +reptiles and mammals, though the conditions, and perhaps the presence of +a bone like the post-orbital bone, are paralleled only among Reptiles. +The Pterodactyles differ among themselves enough for the head to make a +near approach to Reptiles in Dimorphodon, and to Birds in +Pterodactylus. In the Ground Hornbill and the Shoebill the lachrymal +bones in front of the orbits of the eyes grow down to meet the malar +bars without uniting with them. The post-frontal region also is +prolonged downward almost as far as the malar bar, as though to show +that a bird might have its orbital circle formed in the same way and by +the same bones as in Pterodactylus. Cretaceous Ornithosaurs sometimes +differ from birds apparently in admitting the quadrato-jugal bone into +the orbit. It then becomes an expanded plate, instead of a slender bar +as in all birds. + + +THE TEMPORAL FOSSA + +A fourth vacuity is known as the temporal fossa. When the skull of such +a mammal as a Rabbit, or Sheep, is seen from above, there is a vacuity +behind the orbits for the eyes, which in life is occupied by the muscles +which work the lower jaw. It is made by the malar bone extending from +the back of the orbit and the process of bone, called the zygomatic +process, extending forward from the articulation of the jaw, which +arches out to meet the malar bone. + +In birds there is no conspicuous temporal fossa, because the malar bar +is a slender rod of bone in a line with the lower end of the quadrate +bone. + +Reptile skulls have sometimes one temporal vacuity on each side, as +among tortoises, formed by a single lateral bar. These vacuities, which +correspond to those of mammals in position, are seen from the top of the +head, as lateral vacuities behind the orbits of the eyes, and are termed +superior temporal vacuities. In addition to these there is often in +other reptiles a lateral opening behind the eye, termed the inferior +temporal vacuity, seen in Crocodiles, in Hatteria, and in Lizards; and +in such skulls there are two temporal bars seen in side view, +distinguished as superior and inferior. The superior arch always +includes the squamosal bone, which is at the back of the single bar in +mammals. The lower arch includes the malar bone, which is in front in +the single arch of mammals. The circumstance that both these arches are +connected with the quadrate bone makes the double temporal arch +eminently reptilian. + +In Ornithosaurs the lateral temporal vacuity varies from a typically +reptilian condition to one which, without becoming avian, approaches the +bird type. In skulls from the Lias, Dimorphodon and Campylognathus, +there is a close parallel to the living New Zealand reptile Hatteria, in +the vertical position of the quadrate bone and in the large size of the +vacuity behind and below the eye, which extends nearly the height of the +skull. In the species of the genus Pterodactylus, the forward +inclination of the quadrate bone recalls the Curlew, Snipe, and other +birds. The back of the head is rounded, and the squamosal bone, which +appears to enter into the wall of the brain case as in birds and +mammals, is produced more outward than in birds, but less than in +mammals, so as to contribute a little to the arch which is in the +position of the post-frontal bone of reptiles. It is triangular, and +stretches from the outer angle of the frontal bone at the back of the +orbit to the squamosal behind, where it also meets the quadrate bone. +Its third lower branch meets the quadratojugal, which rests upon the +front of the quadrate bone, as in Iguanodon, and is unlike Dimorphodon +in its connexions. In that genus the supra-temporal bone, or +post-orbital bone, appears to rest upon the post-frontal and connect it +with the quadrato-jugal. In Dimorphodon the malar bone is entirely +removed from the quadrate, but in Pterodactylus it meets its articular +end. Between the post-frontal bone above and the quadrato-jugal bone +below is a small lunate opening, which represents the lateral temporal +vacuity; and so far, this is a reptilian character. But if the thin +post-frontal bone were absorbed, Pterodactylus would resemble birds. +There is no evidence that the quadrate bone is free in any Ornithosaurs, +as it is in all birds, while in Dimorphodon it unites by suture with the +squamosal bone. In Ornithostoma the lateral temporal vacuity is little +more than a slit between the quadrate bone below, the quadrato-jugal in +front, and what may be the post-frontal bone behind (see Fig. 2, p. 12). + + +BONES ABOUT THE BRAIN + +The bones containing the brain appear to be the same as form the brain +case in birds. The form of the back of the skull varies in two ways. +First it may be flat above and flat at the back, when the back of the +head appears to be square. This condition is seen in all the long-tailed +genera, such as Campylognathus from the Lias and Rhamphorhynchus, and is +associated with a high position for the upper temporal bar. Secondly, +the back of the head may be rounded convexly, both above and behind. +That condition is seen in the short-tailed genera, such as +Pterodactylus. But in the large Cretaceous types, such as Ornithocheirus +and Ornithostoma, the superior longitudinal ridge which runs back in +the middle line of the face becomes elevated and compressed from side to +side at the back of the head as a narrow deep crest, prolonged backward +over the neck vertebrae for some inches of length. All these three types +are paralleled more or less in birds which have the back of the head +square like the Heron, or rounded like the Woodpecker; or crested, +though the crest of the Cormorant is not quite identical with +Ornithocheirus, being a distinct bone at the back of the head in the +bird which never blends with the skull. In so far as the crest is +reptilian it suggests the remarkable crest of the Chameleon. In the +structure of the back of the skull the bones are a modification of the +reptilian type of Hatteria in the Lias genus Campylognathus, but the +reptilian characters appear to be lost in the less perfectly preserved +skulls of Cretaceous genera. + +The palate is well known in the chief groups of Ornithosaurs, such as +Campylognathus, Scaphognathus, and Cycnorhamphus. + +Mr. E. T. Newton, F.R.S., has shown that in the English skull from the +Lias of Whitby, the forms of the bones are similar to the palate in +birds and unlike the conditions in reptiles. There is one feature, +however, which may indicate a resemblance to Dicynodon and other fossil +reptiles from South Africa. A slender bone extends from the base of the +brain case, named the basi-sphenoid bone, outward and forward to the +inner margin of the quadrate bone (Fig. 22). A bone is found thus placed +in those South African Reptiles, which show many resemblances to the +Monotreme and Marsupial Mammals. It is not an ordinary element of the +skeleton and is unknown in living animals of any kind in that position. +It has been thought possible that it may represent one of the bones +which among mammals are diminutive and are included in the internal ear. +The resemblance may have some interest hereafter, as helping to show +that certain affinities of the Ornithosaurs may lie outside the groups +of existing reptiles. Instead of being directed transversely outward, as +in the palatal region of _Dicynodon lacerticeps_, they diverge outward +and forward to the inner border of the articulation for the lower jaw +which is upon the quadrate bone. + + [Illustration: FIG. 22] + + +BONES OF THE PALATE + +There is a pair of bones which extend forward from these inner articular +borders of the quadrate bones, and converge in a long #V#-shape till +they merge in the hard palate formed by the bones of the front of the +beak, named intermaxillary and maxillary bones. The limits of the bones +of the palate are not distinct, but there can be no doubt that the +front of the #V# is the bone named vomer, that the palatine bones are at +its sides, and that its hinder parts are the pterygoid bones as in +birds. There is a long, wide, four-sided, open space in the middle of +the palate, between the vomer and the basi-sphenoid bone, unlike +anything in birds or other animals. + +Professor Marsh, in a figure of the palate in the great skull of the +toothless Pterodactyle named Ornithostoma (Pteranodon), from the Chalk +of Kansas, found a large oval vacuity in this region of the palate. In +that genus the pterygoid bones meet each other between the quadrate +bones as in Dicynodon (Fig. 73, p. 182). Hence the great palatal vacuity +here seen in the Ornithosaur is paralleled by the small vacuity in the +South African reptile, which is sometimes distinct and sometimes partly +separated from the anterior part of the vacuity which forms the openings +of the nostrils on the palate. + +The Solenhofen skulls which give any evidence of the palate are exposed +in side view only, and the bones, imperfectly seen through the lateral +vacuities, are displaced by crushing. They include long strips like the +vomerine bones in the Lias fossil, and they diverge in the same way as +they extend back to the quadrate bones. The oblique division into vomer +in front and pterygoid bone behind is shown by Goldfuss in his original +figure of Scaphognathus. Thus there is some reason for believing that +all Ornithosaurs have the palate formed upon the same general plan, +which is on the whole peculiar to the group, especially in not having +the palatal openings of the nares divided in the middle line. It would +appear probable that the short-tailed animals have the pterygoid bones +meeting in the middle line and triangular; and that they are slender +rods entirely separate from each other in the long-tailed genera. + + +THE TEETH + +The teeth are all of pointed, elongated shape, without distinction into +the kinds seen in most mammals and named incisors, canines, and +grinders. They are organs for grasping, like the teeth of the +fish-eating Crocodile of India, and are not unlike the simple teeth of +some Porpoises. They are often implanted in oblique oval sockets with +raised borders, usually at some distance apart from each other, and have +the crown pointed, flattened more on the outer side than on the inner +side, usually directed forward and curved inward. As in many extinct +animals allied to existing reptiles, the teeth are reproduced by germs, +which originate on the inner side of the root and grow till they +gradually absorb the substance of the old tooth, forming a new one in +its place. Frequently in Solenhofen genera, like Scaphognathus and +Pterodactylus, the successional tooth is seen in the jaw on the hinder +border of the tooth in use. There is some variation in the character of +bluntness or sharpness of the crowns in the different genera, and in +their size. + +The name Dimorphodon, given to the animal from the Lias of Lyme Regis, +expresses the fact that the teeth are of two kinds. In the front of the +jaw three or four large long teeth are found in the intermaxillary bone +on each side, as in some Plesiosaurs, while the teeth found further back +in the maxillary bone are smaller, and directed more vertically +downward. This difference is more marked in the lower jaw than in the +upper jaw. In Rhamphorhynchus the teeth are all relatively long and +large, and directed obliquely forward, but absent from the extremities +of the beak, as in the German genus from the Lias named Dorygnathus, in +which the bone of the lower jaw (which alone is known) terminates in a +compressed spear. In Scaphognathus the teeth are few, more vertical, and +do not extend backward so far as in Rhamphorhynchus, but are carried +forward to the extremity of the blunt, deep jaw. + +In the short-tailed Pterodactyles the teeth are smaller, shorter, wider +at the base of the crown, closer together, and do not extend so far +backward in the jaw. In Ornithocheirus two teeth always project forward +from the front of the jaw. Ornithostoma is toothless. + + +SUPPOSED HORNY BEAK + +Sometimes a horny covering has been suggested for the beak, like that +seen in birds or turtles, but no such structure has been preserved, even +in the Solenhofen Slate, in which such a structure would seem as likely +to be preserved as a wing membrane, though there is one doubtful +exception. There are marks of fine blood vessels on some of the jaws, +indicating a tough covering to the bone. In Rhamphorhynchus the jaws +appear to gape towards their extremities as though the interspace had +originally been occupied by organic substance like a horny beak. + + +LOWER JAW + +The lower jaw varies in relative length with the vertical or horizontal +position of the quadrate bone in the skull. In Dimorphodon the jaw is as +long as the skull; but in the genera from the Oolitic rocks the +mandible is somewhat shorter, and in Ornithostoma the discrepancy +reaches its maximum. The hinder part of the jaw is never prolonged +backward much beyond the articulation, differing in this respect from +Crocodiles and Plesiosaurs. + +The depth of the jaw varies. It is slender in Pterodactylus, and is +probably stronger relatively to the skull in Scaphognathus than in any +other form. It fits between the teeth and bones of the alveolar border +in the skull, in all the genera. In Dimorphodon its hinder border is +partly covered by the descending edge of the malar process which these +animals develop in common with some Dinosaurs, and some Anomodont +reptiles, and many of the lower mammals. In this hinder region the lower +jaw is sometimes perforated, in the same way as in Crocodiles. That +condition is observed in Dimorphodon, but is not found in Pterodactylus. +The lower jaw is always composite, being formed by several bones, as +among reptiles and birds. The teeth are in the dentary bone or bones, +and these bones are almost always blended as in most birds and Turtles, +and not separate from each other as among Crocodiles, Lizards, and +Serpents. + +An interesting contour for the lower border of the jaw is seen in +Ornithostoma, as made known in figures of American examples by +Professors Marsh and Williston. It deepens as it extends backwards for +two-thirds its length, stops at an angle, and then the depth diminishes +to the articulation with the skull. This angle of the lower jaw is a +characteristic feature of the jaws of Mammals. It is seen in the +monotreme Echidna, and is characteristic of some Theriodont Reptiles +from South Africa, which in many ways resemble Mammals. The character +is not seen in the jaws of specimens from the Oolitic rocks, but is +developed in the toothed Ornithocheirus from the Cambridge Greensand, +and is absent from the jaws of existing reptiles and birds. + + [Illustration: FIG. 23 COMPARISON OF THE LOWER JAW IN ECHIDNA AND + ORNITHOSTOMA] + + +SUMMARY OF CHARACTERS OF THE HEAD + +Taken as a whole, the head differs from other types of animals in a +blending of characters which at the present day are found among Birds +and Reptiles, with some structures which occur in extinct groups of +animals with similar affinities, and perhaps a slight indication of +features common to the lowest mammals. It is chiefly upon the head that +the diverse views of earlier writers have been based. Cuvier was +impressed with the reptilian aspect of the teeth; but in later times +discoveries were made of Birds with teeth--Archaeopteryx, Ichthyornis, +Hesperornis. The teeth are quite reptilian, being not unlike miniature +teeth of Mosasaurus. If those birds had been found prior to the +discovery of Pterodactyles, the teeth might have been regarded as a link +with the more ancient birds, rather than a crucial difference between +birds and reptiles. + +All the specimens show a lateral temporal hole in the bones behind the +eye, and this is found in no bird or mammal, and is typical of such +reptiles as Hatteria. The quadrate bone may not be so decisive as Cuvier +thought it to be, for its form is not unlike the quadrate of a bird, and +different, so far as I have seen, from that of living reptiles. This +region of the head is reptilian, and if it occurred in a bird the +character would be as astonishing as was the discovery of teeth in +extinct birds. These characters of the head are also found in fossil +animals named Dinosaurs, in association with many resemblances to birds +in their bones. + +The palate might conceivably be derived from that of Hatteria by +enlarging the small opening in the middle line in that reptile till it +extended forward between the vomera; but it is more easily compared with +a bird, which the animal resembles in its beak, and in the position of +the nares. Excepting certain Lizards, all true existing Reptiles have +the nostrils far forward and bordered by two premaxillary bones instead +of one intermaxillary, as in Birds and Ornithosaurs. If nothing were +known of the animal but its head bones, it would be placed between +Reptiles and Birds. + + + + +CHAPTER IX + +THE BACKBONE, OR VERTEBRAL COLUMN + + +The backbone is a more deep-seated part of the skeleton than the head. +It is more protected by its position, and has less varied functions to +perform. Therefore it varies less in distinctive character within the +limits of each of the classes of vertebrate animals than either the head +or limbs. It is divided into neck bones, the cervical vertebrae; back +bones, the dorsal vertebrae; loin bones, the lumbar vertebrae; the sacrum, +or sacral vertebrae, which support the hind limbs; and the tail. Of these +parts the tail is the least important, though it reaches a length in +existing reptiles which sometimes exceeds the whole of the remainder of +the body, and includes hundreds of vertebrae. It attains its maximum +among serpents and lizards. In frogs it is practically absent. In some +of the higher mammals it is a rudiment, which does not extend beyond the +soft parts of the body. + + +THE NECK + +The neck is more liable to vary than the back, with the habit of life of +the animal. And although mammals almost always preserve the same number +of seven bones in the neck, the bones vary in length between the short +condition of the porpoise, in which the neck is almost lost, and the +long bones which form the neck of the Llama, though even these may be +exceeded by some fossil reptiles like Tanystrophoeus. In many mammals +the neck bones do not differ in length or size from those of the back. +In others, like the Horse and Ox, they are much broader and larger. + +There is the same sort of variation in the bones of the neck among +birds, some being slender like the Heron, others broad like the Swan. +But there is also a singular variation in number of vertebral bones in a +bird's neck. At fewest there are nine, which equals the exceptionally +large number found among mammals in the neck of one of the Sloths. +Usually birds have ten to fifteen cervical vertebrae, and in the Swan +there are twenty-three. Most of the neck bones of birds are relatively +long, and the length of the neck is often greater than the remainder of +the vertebral column. + +Reptiles usually have short necks. The common Turtle has eight bones in +the neck, ten in the back. The two regions are sharply defined by the +dorsal shield. Their articular ends are sometimes cupped in front, in +the neck, sometimes cupped behind, or convex at both ends, or even +flattened, or the articulation may be made exceptionally by the neural +arch alone. Nine is the largest number of neck bones in existing +Lizards, and there are usually nine in Crocodiles; so that reptiles +closely approach mammals in number of the neck bones. It is remarkable +that the maximum number in a mammal and in living reptiles should +coincide with the minimum number in birds. Therefore the number of +cervical vertebrae as an attribute of Mammal, Bird, or Reptile, can only +be important from its constancy. + +German naturalists affirm on clear evidence that the Solenhofen +Pterodactyles have seven cervical vertebrae. In many specimens there can +be no doubt about the number, because the neck bones are easily +distinguished from those of the back by their size; but the number is +not always easy to count. + +As in Birds, the first vertebra, or atlas, in Pterodactyles is extremely +short, and is generally--if not always--blended with the much longer +second vertebra, named the axis. The front of the atlas forms a small +rounded cup to articulate with the rounded ball of the basioccipital +bone at the back of the skull. The third and fourth vertebrae are longer, +but the length visibly shortens in the sixth and seventh. + +Sometimes the vertebrae are slender and devoid of strong spinous +processes. This is the condition in the little _Pterodactylus +longirostris_ and in the comparatively large _Cycnorhamphus Fraasii_, in +which there is a slight median ridge along the upper surface of the arch +of the vertebra. This condition is paralleled in birds with long necks, +especially wading birds such as the Heron. Other Ornithosaurs, such as +Ornithocheirus from the Cretaceous rocks, have the neck much more +massive. The vertebrae are flattened on the under side. The arch above +the nervous matter of the spinal cord has a more or less considerable +transverse expansion, and may even be as wide as long. These vertebrae +have proportions and form such as may be seen in Vultures or in the +Swan. In either case the form of the neck bones is more or less +bird-like, and the neural spine may be elevated, especially in +Pterodactyles with long tails. + +One of the most distinctive features of the neck bones of a bird is the +way in which the cervical ribs are blended with the vertebrae. They are +small, and each is often prolonged in a needle-like rod at the side of +the neck bone. + +In Ornithocheirus the cervical rib similarly blends with the vertebra by +two articulations, as in mammals, so that it might escape notice but for +the channel of a blood vessel which is thus inclosed. In several of the +older Pterodactyles from Solenhofen the ribs of the neck vertebrae remain +separated, as in a Crocodile, though still bird-like in their form, +anterior position, and mode of attachment. In Terrapins and Tortoises +the long neck vertebrae have no cervical ribs. + + [Illustration: FIG. 24 UNITED ATLAS AND AXIS OF ORNITHOCHEIRUS + (Cambridge Greensand)] + +The articular surfaces between the bodies of the vertebrae, in the neck, +are transversely oval. The middle part of this articular joint is made +by the body of the vertebra; its outer parts are in the neural arch. In +front this surface is a hollow channel, often more depressed than in any +other animals. The corresponding surface behind is convex, with a +process on each side at its lower outer angles (Fig. 25). It is a +modification of the cup-and-ball form of vertebral articulation, which +at the present day is eminently reptilian. Serpents and Crocodiles have +the articulations similarly vertical, but in both the form of the +articulation is a circle. In Lizards the articular cup is usually rather +wider than deep, when the cup and ball are developed in the vertebrae; it +differs from the vertical condition in pterodactyles in being oblique +and much narrower from side to side. Only among Crocodiles and Hatteria +is there a double articulation for the cervical rib, though in neither +order have rib or vertebra in the neck the bird-like proportions which +are usual in these animals. Pterodactyles show no resemblance to birds +in this vertebral articulation. A Bird has the corresponding surface +concave from side to side in front, but it is also convex from above +downward, producing what is known as the saddle-shaped form which is +peculiarly avian, being found in existing birds except in part of the +back in Penguins. It is faintly approximated to in one or two neck +vertebrae in man. Professor Williston remarks that in the toothless +Pterodactyles of Kansas the hinder ball of the vertebral articulation is +continued downward and outward as a concave articulation upon the +processes at its outer corners. There are no mammals with a cup-and-ball +articulation between the vertebrae, so that for what it is worth the +character now described in Ornithosaurs is reptilian, when judged by +comparison with existing animals. + + [Illustration: FIG. 25. CERVICAL VERTEBRA OF ORNITHOCHEIRUS + From the Cambridge Greensand] + +Low down on each side of the vertebra, at the junction of its body with +the neural arch, is a large ovate foramen, transversely elongated, and +often a little impressed at the border, which is the entrance of the +air cell into the bone. These foramina are often one-third of the length +of the neck vertebrae in specimens from the Cambridge Greensand, where +the neck bones vary from three-quarters of an inch to about two and a +half inches in length, and in extreme forms are as wide as long. The +width of the interspace between the foramina is one-half the width of +the vertebrae, though this character varies with different genera and +species. Several species from the Solenhofen Slate have the neck long +and slender, on the type of the Flamingo. In others the neck is thick +and short--in the _Scaphognathus crassirostris_ and _Pterodactylus +spectabilis_. Some genera with slender necks have the bones preserved +with a curved contour, such as might suggest a neck carried like that of +a Llama or a Camel. The neck is occasionally preserved in a curve like a +capital #S#, as though about to be darted forward like that of a bird in +the act of striking its prey. The genera of Pterodactyles with short +necks may have had as great mobility of neck as is found among birds +named Ducks and Divers; but those Pterodactyles with stout necks, such +as Dimorphodon and Ornithocheirus, in which the vertebrae are large, +appear to have been built more for strength than activity, and the neck +bones have been chiefly concerned in the muscular effort to use the +fighting power of the jaws in the best way. + + +THE BACK + +The region of the back in a Pterodactyle is short as compared with the +neck, and relatively is never longer than the corresponding region in a +bird. The shortness results partly from the short length of the +vertebrae, each of which is about as long as wide. There is also a +moderate number of bones in the back. In most skeletons from Solenhofen +these vertebrae between the neck and girdle of hip bones number from +twelve to sixteen. They have a general resemblance in form to the dorsal +vertebrae in birds. The greatest number of such vertebrae in birds is +eleven. The number is small because some of the later vertebrae in birds +are overlapped by the bones of the hip girdle, which extend forward and +cover them at the sides, so that they become blended with the sacrum. +This region of the skeleton in the Dimorphodon from the Lias is +remarkable for the length of the median process, named the neural spine, +which is prolonged upward like the spines of the early dorsal vertebrae +of Horses, Deer, and other mammals. In this character they differ from +living reptiles, and parallel some Dinosaurs from the Weald. The bones +of the back in Ornithocheirus from the Cambridge Greensand show the +under side to be well rounded, so that the articular surfaces between +the vertebrae, though still rather wider than deep, are much less +depressed than in the region of the neck. The neural canal for the +spinal cord has become larger and higher, and the sides of the bone are +somewhat compressed. Strong transverse processes for the support of the +ribs are elevated above the level of the neural canal, at the sides of +vertebrae compressed on the under sides, and directed outward. Between +these lateral horizontal platforms is the compressed median neural +spine, which varies in vertical height. The articulation of the ribs is +not seen clearly. Isolated ribs from the Stonesfield Slate have +double-headed dorsal ribs, like those of birds. In some specimens from +the Solenhofen Slate like the Scaphognathus, in the University Museum at +Bonn, dorsal ribs appear to be attached by a notch in the transverse +process of the dorsal vertebra, which resembles the condition in +Crocodiles. Variations in the mode of attachment of ribs among mammals +may show that character to be of subordinate importance. Von Meyer has +described the first pair of ribs as frequently larger than the others, +and there appear in Rhamphorhynchus to be examples preserved of the +sternal ribs, which connect the dorsal ribs with the sternum. Six pairs +have been counted. A more interesting feature in the ribs consists in +the presence behind the sternum, which is shorter than the corresponding +bone in most birds, of median sternal ribs. They are slender #V#-shaped +bones in the middle line of the abdomen, which overlapped the ends of +the dorsal ribs like the similar sternal bones of reptiles. Such +structures are unknown among Birds and Mammals. There is no trace in the +dorsal ribs of the claw-like process, which extends laterally from rib +to rib as a marked feature in many birds. Its presence or absence may +not be important, because it is represented by fibro-cartilage in the +ribs of crocodiles, and may be a small cartilage near the head of the +rib in serpents, and is only ossified in some ribs of the New Zealand +reptile Hatteria. So that it might have been present in a fossil animal +without being ossified and preserved. Although the structure is +associated with birds, it is possibly also represented by the great bony +plates which cover the ribs in Chelonians, and combine to form the +shield which covers the turtle's back. The structure is as +characteristic of reptiles as of birds, but is not necessarily +associated with either. + + [Illustration: FIG. 26 + + The upper figures show the side and back of a dorsal vertebra of + Ornithocheirus compared with corresponding views of the side and + back of a dorsal vertebra of a Crocodile] + +There are two remarkable modifications of the early dorsal vertebrae in +some of the Cretaceous Pterodactyles. First, in the genus Ornithodesmus +from the Weald the early dorsal vertebrae are blended together into a +continuous mass, like that which is found in the corresponding region of +the living Frigate-bird, only more consolidated, and similar to that +consolidated structure found behind the dorsal vertebrae, known as the +sacrum, made by the blending of the vertebrae into a solid mass which +supports the hip bones. Secondly, in some of the Cretaceous genera of +Pterodactyles of Europe and America the vertebrae in the front part of +the back are similarly blended, but their union is less complete; and in +genera Ornithocheirus and Ornithostoma--the former chiefly English, the +latter chiefly American--the sides of the neural spines are flattened to +form an oval articular surface on each side, which gives attachment to +the flattened ends of their shoulder-blade bones named the scapulae. This +condition is found in no other animals. Three vertebrae appear to have +their neural arches thus united together. The structure so formed may be +named the notarium to distinguish it from the sacrum. + + +SACRUM + +For some mysterious reason the part of the backbone which lies between +the bones of the hips and supports them is termed the sacrum. Among +living reptiles the number of vertebrae in this region is usually two, as +in lizards and crocodiles. There are other groups of fossil reptiles in +which the number of sacral vertebrae is in some cases less and in other +cases more. There is, perhaps, no group in which the sacrum makes a +nearer approach to that of birds than is found among these +Pterodactyles, although there are more sacral vertebrae in some +Dinosaurs. In birds the sacral vertebrae number from five to twenty-two. +In bats the number is from five to six. In some Solenhofen species, such +as _Pterodactylus dubius_ and _P. Kochi_ and _P. grandipelvis_, the +number is usually five or six. The vertebrae are completely blended. The +pneumatic foramina in the sacrum, so far as they have been observed, are +on the under sides of the transverse processes; while in the +corresponding notarial structure in the shoulder girdle the foramina are +in front of the transverse processes. Almost any placental mammal in +which the vertebrae of the sacral region are anchylosed together has a +similar sacrum, which differs from that of birds in the more complete +individuality of the constituent bones remaining evident. The transverse +processes in front of the sacrum are wider than in its hinder part; so +that the pelvic bones which are attached to it converge as they extend +backward, as among mammals. The bodies of the vertebrae forming the +sacrum are similar in length to those of the back. Each transverse +process is given off opposite the body of its own vertebra, but from a +lower lateral position than in the region of the back, in which the +vertebrae are free. + + [Illustration: FIG. 27. SACRUM OF RHAMPHORHYNCHUS + + Showing the complete blending of the vertebrae and ribs as in a bird, + with the well-defined Iliac bones, produced chiefly in front of the + acetabulum for the head of the femur.] + +The hip bones are closely united with the sacrum by bony union, and +rarely appear to come away from the sacral vertebrae, as among mammals +and reptiles, though this happens with the Lias Pterodactyles. In the +Stonesfield Slate and Solenhofen Slate the slender transverse processes +from the vertebrae blend with the ilium of the hip girdle, and form a +series of transverse foramina on each side of the bodies of the +vertebrae. In the Cambridge Greensand genera the part of the ilium above +the acetabulum for the articular head of the femur appears to be always +broken away, so that the relation of the sacrum to the pelvis has not +been observed. This character is no mark of affinity, but only shows +that ossification obliterated sutures among these animals in the same +way as among birds. + +The great difference between the sacrum of a Pterodactyle and that of a +bird has been rendered intelligible by the excellent discussion of the +sacral region in birds made by Professor Huxley. He showed that it is +only the middle part of the sacrum of a chicken which corresponds to the +true sacrum of a reptile, and comprises the five shortest of the +vertebrae; while the four in front correspond to those of the lower part +of the back, which either bear no ribs or very short ribs, and are known +as the lumbar region in mammals, so that the lower part of the back +becomes blended with the sacrum, and thus reduces the number of dorsal +vertebrae. Similarly the five vertebrae which follow the true sacral +vertebrae are originally part of the tail, and have been blended with the +other vertebrae in front, in consequence of the extension along them of +the bird's hip bones. This interpretation helps to account for the great +length of the sacrum in many birds, and also explains in part the +singular shortness of the tail in existing birds. The Ornithosaur sacrum +has neither the lumbar nor the caudal portions of the sacrum of a bird. + + + +THE TAIL + +The tail is perhaps the least important part of the skeleton, since it +varies in character and length in different genera. The short tails seen +in typical pterodactyles include as few as ten vertebrae in +_Pterodactylus grandipelvis_ and _P. Kochi_, and as many as fifteen +vertebrae in _Pterodactylus longirostris_. The tails are more like those +of mammals than existing birds, in which there are usually from six to +ten vertebrae terminating in the ploughshare bone. But just as some +fossil birds, like the Archaeopteryx, have about twenty long and slender +vertebrae in the tail, so in the pterodactyle Rhamphorhynchus this region +becomes greatly extended, and includes from thirty-eight to forty +vertebrae. In Dimorphodon the tail vertebrae are slightly fewer. The +earliest are very short, and then they become elongated to two or three +times the length of the early tail vertebrae, and finally shorten again +towards the extremity of the tail, where the bones are very slender. In +all long-tailed Ornithosaurians the vertebrae are supported and bordered +by slender ossified ligaments, which extend like threads down the tail, +just as they do in Rats and many other mammals and in some lizards. + +Professor Marsh was able to show that the extremity of the tail in +Rhamphorhynchus sometimes expands into a strong terminal caudal membrane +of four-sided somewhat rhomboidal shape. He regards this membrane as +having been placed vertically. It is supported by delicate processes +which represent the neural spines of the vertebrae prolonged upward. They +are about fifteen in number. A corresponding series of spines on the +lower border, termed chevron bones, equally long, were given off from +the junctions of the vertebrae on their under sides, and produced +downward. This vertical appendage is of some interest because its +expansion is like the tail of a fish. It suggests the possibility of +having been used in a similar way to the caudal fin as an organ for +locomotion in water, though it is possible that it may have also formed +an organ used in flight for steering in the air. + + [Illustration: FIG. 28. EXTREMITY OF THE TAIL OF _RHAMPHORHYNCHUS + PHYLLURUS_ (MARSH) + + Showing the processes on the upper and under sides of the vertebrae + which make the terminal leaf-like expansion] + +The tail vertebrae from the Cambridge Greensand are mostly found isolated +or with not more than four joints in association. They are very like the +slender type of neck vertebrae seen in long-necked pterodactyles, but are +depressed, and though somewhat wider are not unlike the tail vertebrae of +the Rhamphorhynchus. The pneumatic foramen in them is a mere puncture. +They have no transverse processes or neural spines, nor indications of +ribs, or chevron bones. + +The hindermost specimens of tail vertebrae observed have the neural arch +preserved to the end, as among reptiles; whereas in mammals this arch +becomes lost towards the end of the tail. The processes by which the +vertebrae are yoked together are small. There is nothing to suggest that +the tail was long, except the circumstance that the slender caudal +vertebrae are almost as long as the stout cervical vertebrae in the same +animal. No small caudal vertebrae have ever been found in the Cambridge +Greensand. The tail is very short, according to Professor Williston, in +the toothless Ornithostoma in the Chalk of Kansas. + + + + +CHAPTER X + +THE HIP-GIRDLE AND HIND LIMB + + +The bones of the hip-girdle form a basin which incloses and protects the +abdominal vital organs. It consists on each side of a composite bone, +the unnamed bones--_ossa innominata_ of the older anatomists--which are +each attached to the sacrum on their inner side, and on the outer side +give attachment to the hind limbs. As a rule three bones enter into the +borders of this cup, termed the acetabulum, in which the head of the +thigh bone, named the Femur, moves with a more or less rotary motion. + +There are a few exceptions in this division of the cup between three +bones, chiefly among Salamanders and certain Frogs. In Crocodiles the +bone below the acetabular cup is not divided into two parts. And in +certain Plesiosaurs from the Oxford Clay--Muraenosaurus--the actual +articulation appears to be made by two bones--the ilium and ischium. The +three bones which form each side of the pelvis are known as the ilium, +or hip bone, sometimes termed the aitch bone; secondly, the ischium, or +sitz bone, being the bone by which the body is supported in a sitting +position; and thirdly the pubis, which is the bone in front of the +acetabulum. The pubic bones meet in the middle line of the body on the +under side of the pelvis in man, and on each side are partly separated +from the ischia by a foramen, spoken of as the obturator foramen, which +in Pterodactyles is minute and almost invisible, when it exists. + +There is often a fourth bony element in the pelvis. In some Salamanders +a single cartilage is directed forward, and forked in front. According +to Professor Huxley something of this kind is seen in the Dog. The pair +of bones which extend forward in front of the pelvis in Crocodiles may +be of the same kind, in which case they should be called prepubic bones. +But among the lower mammals named marsupials a pouch is developed for +the protection of the young and supported by two slender bones attached +to the pubes, and these bones have long been known as marsupial bones. +In a still lower group of mammalia named monotremata, which lay eggs, +and in many ways approximate to reptiles and birds, stronger bones are +developed on the front edge of the pubes, and termed prepubic bones. +They do not support a marsupium. + +Naturalists have been uncertain as to the number of bones in the pelvis +of Pterodactyles, because the bones blend together early in life, as in +birds. Some follow the Amphibian nomenclature, and unite the ischium and +pubis into one bone, which is then termed ischium, when the prepubis is +termed the pubis, and regarded as removed from the acetabulum. There is +no ground for this interpretation, for the sutures are clear between the +three pelvic bones in the acetabulum in some specimens, like +_Cycnorhamphus Fraasii_, from Solenhofen, and some examples of +Ornithocheirus from the Cambridge Greensand. Pterodactyles all have +prepubic bones, which are only known in Ornithorhynchus and Echidna +among mammals, and are absent from the higher mammals and birds. They +are unknown in any other existing animals, unless present in Crocodiles, +in which ischium and pubis are always undivided. Therefore it is +interesting to examine the characters of the Ornithosaurian pelvis. + +The acetabulum for the head of the femur is imperforate, being a simple +oval basin, as in Chelonian reptiles and the higher Mammals. It never +shows the mark of the ligamentous attachment to the head of the femur, +which is seen in Mammals. In Birds the acetabulum is perforated, as in +many of the fossils named Dinosaurs, and in Monotremata. + + [Illustration: FIG. 29. COMPARISON OF THE LEFT SIDE OF THE PELVIS IN + A BIRD AND A PTERODACTYLE] + +Secondly, the ilium is elongated, and extends quite as much in front of +the acetabulum as behind it. The bone is not very deep in this front +process. Among existing animals this relation of the bone is nearer to +birds than to any other type, since birds alone have the ilium extended +from the acetabulum in both directions. The form of the Pterodactyle +ilium is usually that of the embryo bird, and its slender processes +compare in relative length better with those of the unhatched fowl and +Apteryx of New Zealand than with the plate-like form in adult birds. + +In mammals the ilium is directed forward, and even in the Cape ant-eater +Orycteropus there is only an inappreciable production of the bone +backward behind the acetabulum. Among reptiles the general position of +the acetabulum is at the forward termination of the ilium, though the +Crocodile has some extension of the bone in both directions, without +forming distinct anterior and posterior processes. This anterior and +posterior extension of the ilium is seen in the Theriodont reptiles of +Russia and of South Africa, as well as in Dinosaurs. + + [Illustration: FIG. 30. LEFT PELVIC BONES WITH PREPUBIC BONE IN + _PTERODACTYLUS LONGIROSTRIS_] + +Thirdly, in all pterodactyles the ischium and pubis are more or less +completely blended into a sheet of bone, unbroken by perforation, though +there is usually a minute vascular foramen; or the lower border may be +notched between the ischium and the pubis, as in some of the Solenhofen +species, and the pubis does not reach the median line of the body. But +in Dimorphodon the pelvic sheet of bone is unbroken by any notch or +perforation. The notch between the ischium and pubis is well marked in +_Pterodactylus longirostris_, and better marked in _Pterodactylus +dubius_, _Cycnorhamphus Fraasii_, and Rhamphorhynchus. The fossil +animals which appear to come nearest to the Pterodactyles in the +structure of the pelvis are Theriodonts from the Permian rocks of +Russia. The type known as Rhopalodon has the ilium less prolonged front +and back, and is much deeper than in any Pterodactyle; but the +acetabulum is imperforate, and the ischium and pubis are not always +completely separated from each other by suture. In the pelvis referred +to the Theriodont Deuterosaurus there is some approximation to the +pelvis of Rhamphorhynchus and of _Pterodactylus dubius_ in the depth of +the division between the pubis and ischium. + + [Illustration: FIG. 31 PELVIS AND PREPUBIC BONES OF RHAMPHORHYNCHUS + + On the left-hand side the two prepubic bones are separate. On the + right-hand they are united into a transverse bar which overlaps the + front of pelvis seen from the under side] + +There are three modifications of the Ornithosaurian pelvis. First, the +type of Rhamphorhynchus, in which the pubis and ischium are inclined +somewhat backward, and in which the two prepubic bones are triangular, +and are often united together to form a transverse bow in front of the +pubic region. + +Secondly, there is the ordinary form of pelvis in which the pubis and +ischium usually unite with each other down their length, as in +Dimorphodon, but sometimes, as in _Pterodactylus dubius_, divide +immediately below the acetabulum. All these types possess the +paddle-shaped prepubic bones, which are never united in the median line. + +Thirdly, there is the cretaceous form indicated by Ornithocheirus and +Ornithostoma, in which the posterior half of the ilium is modified in a +singular way, since it is more elevated towards the sacrum than the +anterior half, suggesting the contour of the upper border of the ilium +in a lizard. Without being reptilian--the anterior prolongation of the +bone makes that impossible--it suggests the lizards. This type also +possesses prepubic bones. They appear, according to Professor Williston, +to be more like the paddle-shaped bones of Pterodactylus than like the +angular bones in Rhamphorhynchus. The prepubic bones are united in the +median line as in Rhamphorhynchus. But their median union in that genus +favours the conclusion that the bones were united in the median line in +all species, though they are only co-ossified in these two families. + + [Illustration: FIG. 32. THE PELVIC BONES OF AN ALLIGATOR SEEN FROM + BELOW + + The bones in front are here regarded as prepubic, but are commonly + named pubic] + +This median union of the prepubic bones is a difference from those +mammals like the Ornithorhynchus and Echidna, which approach nearest to +the Reptilia. In them the prepubic bones have a long attachment to the +front margin of the pubis, and extend their points forward without any +tendency for the anterior extremities to approximate or unite. The +marsupial mammals have the same character, keeping the marsupial bones +completely distinct from each other at their free extremities. The only +existing animals in which an approximation is found to the prepubic +bones in Pterodactyles are Crocodiles, in bones which most writers term +the pubic bones. This resemblance, without showing any strong affinity +with the Crocodilia, indicates that Crocodiles have more in common with +the fossil flying animals than any other group of existing reptiles; for +other reptiles all want prepubic bones, or bones in front of the pubic +region. + + +THE HIND LIMB + +The hind limb is exceptionally long in proportion to the back. This is +conspicuous in the skeletons of the short-tailed Pterodactyles, and is +also seen in Dimorphodon. In Rhamphorhynchus the hind limb is relatively +much shorter, so that the animal, when on all fours, may have had an +appearance not unlike a Bat in similar position. The limb is +exceptionally short in the little _Ptenodracon brevirostris_. The bones +of the hind limb are exceptionally interesting. One remarkable feature +common to all the specimens is the great elongation of the shin bones +relatively to the thigh bones. The femur is sometimes little more than +half the length of the tibia, and always shorter than that bone. The +proportions are those of mammals and birds. Some mammals have the leg +shorter than the thigh, but mammals and birds alone, among existing +animals, have the proportions which characterise Pterodactyles. The +foot appears to have been applied to the ground not always as in a bird, +but more often in the manner of reptiles, or mammals in which the digits +terminate in claws. + + +THE FEMUR + + [Illustration: FIG. 33. THE FEMUR + + On the right is a front view of femur of a bear. In the middle are + front and side views of the femur of Ornithocheirus. On the left is + the femur of Echidna. These comparisons illustrate the mammalian + characters of the Pterodactyle thigh bone] + +The thigh bone, on account of the small size of many of the specimens, +is not always quite clear evidence as an indication of technical +resemblance to other animals. The bone is always a little curved, has +always a rounded, articular head, and rounded distal condyles. Its most +remarkable features are shown in the large, well-preserved specimens +from the Cambridge Greensand. The rounded, articular head is associated +with a constricted neck to the bone, followed by a comparatively +straight shaft with distal condyles, less thickened than in mammals. No +bird is known, much less any reptile, with a femur like Ornithocheirus. +Only among Mammals is a similar bone known with a distinct neck; and +only a few mammals have the exceptional characters of the rounded head +and constricted neck at all similar to the Cretaceous Pterodactyles. A +few types, such as the higher apes, the Hyrax, and animals especially +active in the hind limb, have a femur at all resembling the Pterodactyle +in the pit for the obturator externus muscle, behind the trochanter +major, such as is seen in a small femur from Ashwell. The femur varies +in different genera, so as to suggest a number of mammalia rather than +any particular animal for comparison. These approximations may be +consequences of the ways in which the bones are used. When functional +modifications of the skeleton are developed, so as to produce similar +forms of bones, the muscles to which they give attachment, which act +upon the bones, and determine their growth, are substantially the same. +In the _Pterodactylus longirostris_ the femur corresponds in length to +about eleven dorsal vertebrae. The end next the shin bone is less +expanded than is usual among Mammals, and rather suggests an approach to +the condition in Crocodiles, in the moderate thickness and breadth of +the articular end, and the slight development of the terminal +pulley-joint. One striking feature of the femur is the circumstance that +the articular head, as compared with the distal end, is directed forward +and very slightly inward and upward. So that allowing for the outward +divergence of the pelvic bones, as they extend forward, there must have +been a tendency to a knock-kneed approximation of the lower ends of the +thigh bones, as in Mammals and Birds, rather than the outward divergence +seen in Reptiles. + +Apparently the swing of the leg and foot, as it hung on the distal end +of the femur, must have tended rather to an inward than to an outward +direction, so that the feet might be put down upon the same straight +line; this arrangement suggests rapid movement. + + [Illustration: FIG. 34. COMPARISON OF THE TIBIA AND FIBULA IN + ORNITHOSAUR AND VULTURE] + + +TIBIA AND FIBULA + +In _Pterodactylus longirostris_ the tibia is slender, more than a fifth +longer than the femur. A crest is never developed at the proximal end, +like that seen in the Guillemot and Diver and other water birds. The +bone is of comparatively uniform thickness down the shaft in most of the +Solenhofen specimens, as in most birds. At the distal end the shin bone +commonly has a rounded, articular termination, like that seen in birds. +This is conspicuous in the _Pterodactylus grandis_. In other specimens +the tarsal bones, which form this pulley, remain distinct from the +tibia; and the upper row of these bones appears to consist of two +bones, like those which in many Dinosaurs combine to form the +pulley-like end of the tibia which represents the bird's drum-stick +bone. They correspond with the ankle bones in man named astragalus and +os calcis. + +Complete English specimens of tibia and fibula are found in the genus +Dimorphodon from the Lias, in which the terminal pulley of the distal +end has some expansion, and is placed forward towards the front of the +tibia, as in some birds. The rounded surface of the pulley is rather +better marked than in birds. The proximal end of the shaft is relatively +stout, and is modified by the well-developed fibula, which is a short +external splint bone limited to the upper half of the tibia, as in +birds; but contributing with it to form the articular surface for the +support of the lower end of the femur, taking a larger share in that +work than in birds. Frequently there is no trace of the fibula visible +in Solenhofen specimens as preserved; or it is extremely slender and +bird-like, as in _Pterodactylus longirostris_. In Rhamphorhynchus it +appears to extend the entire length of the tibia, as in Dinosaurs. In +the specimens from the Cambridge Greensand there is indication of a +small proximal crest to the tibia with a slight ridge, but no evidence +that this is due to a separate ossification. The patella, or knee-cap, +is not recognised in any fossil of the group. There is no indication of +a fibula in the specimens thus far known from the Chalk rocks either of +Kansas in America, or in England. + +The region of the tarsus varies from the circumstance that in many +specimens the tibia terminates downward in a rounded pulley, like the +drum-stick of a bird; while in other specimens this union of the +proximal row of the tarsal bones with the tibia does not take place, and +then there are two rows of separate tarsal bones, usually with two bones +in each row. When the upper row is united with the tibia the lower row +remains distinct from the metatarsus, though no one has examined these +separate tarsal bones so as to define them. + + +THE FOOT + + [Illustration: FIG. 35. METATARSUS AND DIGITS IN THREE TYPES OF + ORNITHOSAURS] + +The foot sometimes has four toes, and sometimes five. There are four +somewhat elongated, slender metatarsal bones, which are separate from +each other and never blended together, as in birds. There has been a +suspicion that the metatarsal bones were separate in the young +Archaeopteryx. In the young of many birds the row of tarsal bones at the +proximal end of the metatarsus comes away, and there is a partial +division between the metatarsal bones, though they remain united in the +middle. And among Penguins, in which the foot bones are applied to the +ground instead of being carried in the erect position of ordinary birds, +there is always a partial separation between the metatarsal bones, +though they become blended together. The Pterodactyle is therefore +different from birds in preserving the bones distinct through life, and +this character is more like Reptiles than Mammals. The individual bones +are not like those of Dinosaurs, and diverge in Rhamphorhynchus as +though the animals were web-footed. There is commonly a rudimentary +fifth metatarsal. It is sometimes only a claw-shaped appendage, like +that seen in the Crocodile. It is sometimes a short bone, completely +formed, and carrying two phalanges in Solenhofen specimens: though no +trace of these phalanges is seen in the large toothless Pterodactyles +from the Cretaceous rocks of North America. In the _Pterodactylus +longirostris_ the number of foot bones on the ordinary digits is two, +three, four, five, as in lizards; but the short fifth metatarsal has +only two toe bones. In Dimorphodon the fifth digit was bent upward, and +supported a membrane for flight. There are slight variations in the +number of foot bones. In the species _Pterodactylus scolopaciceps_ the +number of bones in the toes follows the formula two, three, three, four. +In _Pterodactylus micronyx_ the number is two, three, three, three. The +terminal claws are much less developed than is usual with Birds; and +there is a difference from Bats in the unequal length of the digits. +Taken as a whole, the foot is perhaps more reptilian than avian, and in +some genera is crocodilian. + +The foot is the light foot of an active animal. Von Meyer thought that +the hind legs were too slender to enable the animal to walk on land; and +Professor Williston, of the University of Kansas, remarks that the +rudimentary claws and weak toes indicate that the animal could not have +used the feet effectively for grasping, while the exceedingly free +movement of the femur indicates great freedom of movement of the hind +legs; and he concludes that the function of the legs was chiefly for +guidance in flight through their control over the movements, and +expresses his belief that the animal could not have stood upon the +ground with its feet. There may be evidence to sustain other views. If +the limb bones are reconstructed, they form limbs not wanting in +elegance or length. If it is true, as Professor Williston suggests, that +the weight of his largest animals with the head three feet long, and a +stretch of wing of eighteen or nineteen feet, did not exceed twenty +pounds, there can be no objection to regarding these animals as +quadrupeds, or even as bipeds, on the ground of the limbs lacking the +strength necessary to support the body. The slender toes of many birds, +and even the two toes of the ostrich, may be thought to give less +adequate support for those animals than the metatarsals and digits of +Pterodactyles. + + + + +CHAPTER XI + +SHOULDER-GIRDLE AND FORE LIMB + + +STERNUM + +The sternum is always a distinguishing part of the bony structure of the +breast. In Crocodiles it is a cartilage to which the sternal ribs unite; +and upon its front portion a flat knife-like bone called the +interclavicle is placed. In lizards like the Chameleon, it is a +lozenge-shaped structure of thin bony texture, also bearing a long +interclavicle, which supports the clavicular bones, named collar bones +in man, which extend outward to the shoulder blades. Among mammals the +sternum is usually narrow and flat, and often consists of many +successive pieces in the middle line, on the under side of the body. +Among Bats the anterior part is somewhat widened from side to side, to +give attachment to the collar bones, but the sternum still remains a +narrow bone, much narrower than in Dolphins, and not differing in +character from many other Mammals, notwithstanding the Bat's power of +flight. The bone develops a median keel for the attachment of the +muscles of the breast, but something similar is seen in burrowing +Insectivorous mammals like the Moles. So that, as Von Meyer remarked, +the presence of a keel on the sternum is not in itself sufficient +evidence to prove flight. + +Among birds the sternum is greatly developed. Broad and short in the +Ostrich tribe, it is devoid of a keel; and therefore the keel, if +present in a bird, is suggestive of flight. The keel is differently +developed according to the mode of attachment of the several pectoral +muscles which cover a bird's breast. In several water birds the keel is +strongly developed in front, and dies away towards the hinder part of +the sternum, as in the Cormorant and its allies. The sternum in German +Pterodactyles is most nearly comparable to these birds. + + [Illustration: FIG. 36. COMPARISON OF THE STERNUM] + +In the Solenhofen Slate the sternum is fairly well preserved in many +Ornithosaurs. It is relatively shorter than in birds, and is broader +than long; but not very like the sternum of reptile or mammal in form. +The keel is limited to the anterior part of the shield of the sternum, +as in Merganser and the Cormorant, and is prolonged forward for some +distance in advance of it. Von Meyer noticed the resemblance of this +anterior process to the interclavicle of the Crocodile in position; but +it is more like the keel of a bird's sternum, and is not a separate bone +as in Reptiles. In Pterodactyles from the Cretaceous rocks, the side +bones, called coracoids, are articulated to saddle-shaped surfaces at +the hinder part of the base of this keel, which are parallel in +Ornithocheirus, as in most birds, but overlap in Ornithodesmus, as in +Herons and wading birds. + + [Illustration: FIG. 37. STERNUM IN ORNITHOCHEIRUS FROM THE CAMBRIDGE + GREENSAND + + Showing the strong keel and the facets for the coracoid bones on its + hinder border above the lateral constrictions] + +The keel was pneumatic, and when broken is seen to be hollow, and +appears to have been exceptionally high in Rhamphorhynchus, a genus in +which the wing bones are greatly elongated. Von Meyer found in +Rhamphorhynchus on each side of the sternum a separate lateral plate +with six pairs of sternal ribs, which unite the sternum with the dorsal +ribs, as in the young of some birds. The hinder surface of the sternum +is imperfectly preserved in the toothless Pterodactyles of Kansas. +Professor Williston states that the bone is extremely thin and +pentagonal in outline, projecting in front of the coracoids, in a stout, +blunt, keel-like process, similar to that seen in the Pterodactyles of +the Cambridge Greensand. American specimens have not the same notch +behind the articulation for the coracoid to separate it from the +transverse lateral expansion of the sternal shield. The lateral margin +in the Cambridge Greensand specimens figured by Professor Owen and +myself is broken; but Professor Williston had the good fortune to find +on the margin of the sternum the articular surfaces which gave +attachment to the sternal ribs. The margin of the sternal bone thickens +at these facets, four of which are preserved. The sternum in +Ornithostoma was about four and a half inches long by less than five and +a half inches wide. The median keel extends forward for rather less than +two inches, while in the smaller Cambridge species of Ornithocheirus it +extends forward for less than an inch and a half. + +A sternum of this kind is unlike that of any other animal, but has most +in common with a bird; and may be regarded as indicating considerable +power of flight. The bone cannot be entirely attributed to the effect of +flight, since there is no such expanded sternal shield in Bats. The +small number of sternal ribs is even more characteristic of birds than +mammals or reptiles. + + +THE SHOULDER-GIRDLE + +The bones which support the fore limb are one of the distinctive regions +of the skeleton defining the animal's place in nature. Among most of the +lower vertebrata, such as Amphibians and Reptiles, the girdle is a +double arch--the arch of the collar bone or clavicles in front, and the +arch of the shoulder-blade or scapula behind. The clavicular arch, when +it exists, is formed of three or five parts--a medium bar named the +interclavicle, external to which is a pair of bones called clavicles, +reaching to the front of the scapulae when they are present; and +occasionally there is a second pair of bones called supraclavicles, +extending from the clavicles up the front margins of the scapulae. Thus +the clavicular arch is placed in front of the scapular arch. The +supraclavicles are absent from all living Reptiles, and the clavicles +are absent from Crocodiles. The interclavicle is absent from all mammals +except Echidna and Ornithorhynchus. Clavicles also may be absent in some +orders of mammals. Hence the clavicular arch may be lost, though the +collar bones are retained in man. + +The scapular arch also is more complicated and more important in the +lower than in the higher vertebrata. It may include three bones on each +side named coracoid, precoracoid, and scapula. But in most vertebrates +the coracoid and precoracoid appear never to have been segmented so as +to be separated from each other; and it is only among extinct types of +reptiles, which appear to approximate to the Monotreme mammals, that +separate precoracoid bones are found; though among most mammals, +probably, there are stages of early development in which precoracoids +are represented by small cartilages, though few mammals except Edentata +like the Sloths and Ant-eaters, retain even the coracoids as distinct +bones. Therefore, excepting the Edentata and the Monotremes, the +distinctive feature of the mammalian shoulder-girdle appears to be that +the limbs are supported by the shoulder-blades, termed the scapulae. + +Among reptiles there are several distinct types of shoulder-girdle. +Chelonians possess a pair of bones termed coracoids which have no +connexion with a sternum; and their scapulae are formed of two widely +divergent bars, divided by a deeper notch than is found in any fossil +reptiles. Among Lizards both scapula and coracoid are widely expanded, +and the coracoid is always attached to the sternum. Chameleons have the +blade of the scapula long and slender, but the coracoid is always as +broad as it is long. Crocodiles have the bone more elongated, so that it +has somewhat the aspect of a very strong first sternal rib when seen on +the ventral face of the animal. The bone is perforated by a foramen, +which would probably lie in the line of separation from the precoracoid +if any such separation had ever taken place. The scapula, or +shoulder-blade, of Crocodiles is a similar flat bone, very much shorter +than the scapula of a Chameleon, and more like that of the New Zealand +Hatteria. Thus there is very little in common between the several +reptilian types of shoulder-girdle. + + [Illustration: FIG. 38. COMPARISON OF SCAPULA AND CORACOID IN THREE + PTERODACTYLES AND A BIRD] + +In birds the apparatus for the support of the wings has a far-off +resemblance to the Crocodilian type. The coracoid bones, instead of +being directed laterally outward and upward from the sternum, as among +Crocodiles, are directed forward, so as to prolong the line of the +breast bone, named the sternum. The bird's coracoid is sometimes +flattened towards the breast bone among Swans and other birds; yet as a +rule the coracoid is a slender bar, which combines with the still more +slender and delicate blade of the scapula, which rests on the ribs, to +make the articulation for the upper arm bone. Among reptiles the scapula +and coracoid are more or less in the same straight line, as in the +Ostrich, but in birds of flight they meet at an angle which is less than +a right angle, and where they come in contact the external surface is +thickened and excavated to make the articulation for the head of the +humerus. There is nothing like this shoulder-girdle outside the class of +birds, until it is compared with the corresponding structure in these +extinct animals called Pterodactyles. The resemblance between the two is +surprising. It is not merely the identity of form in the coracoid bone +and the scapula, but the similar angle at which they meet and the +similar position of the articulation for the humerus. Everything in the +Pterodactyle's shoulder-girdle is bird-like, except the absence of the +representative of the clavicles, that forked #V#-shaped bone of the bird +which in scientific language is known as the furculum, and is popularly +termed the "merry-thought." This kind of shoulder-girdle is found in the +genera from the Lias and the Oolitic rocks, both of this country and +Germany. + +In the Cretaceous rocks the scapula presents, in most cases, a different +appearance. The coracoid is an elongated, somewhat triangular bone, +compressed on the outer margin as in birds, but differing alike from +birds and other Pterodactyles in not being prolonged forward beyond the +articulation for the humerus. In these Cretaceous genera, toothed and +toothless alike, the articulation for the upper arm bone truncates the +extremity of the coracoid, so that the bone is less like that of a bird +in this feature. Perhaps it shows a modification towards the crocodilian +direction. The scapula, which unites with the coracoid at about a right +angle, is similarly truncated by the articular surface for the humerus; +but the bone is somewhat expanded immediately beyond the articulation, +and compressed; and instead of being directed backward, it is directed +inward over the ribs to articulate with the neural arches of the early +dorsal vertebrae in the genera found in strata associated with the Chalk. +As the bone approaches this articulation, it thickens and widens a +little, becoming suddenly truncated by an ovate facet, which exactly +corresponds to the transversely ovate impression, concave from front to +back, which is seen in the neural arches of the dorsal vertebrae on which +it fits. This condition is not present in all Cretaceous Pterodactyles. +It does not occur in the Kansas fossil, named by Professor Marsh, +Nyctodactylus. And it appears to be absent from the Pterodactyles of the +English Weald, named Ornithodesmus. + + [Illustration: FIG. 39. THE NOTARIUM + + An ossification which gives attachment to the scapulae seen in the + early dorsal vertebra of Ornithocheirus + + (From the Cambridge Greensand)] + + [Illustration: FIG. 40. RESTORATION OF THE SHOULDER-GIRDLE IN THE + CRETACEOUS ORNITHOCHEIRUS + + Showing how the scapulae articulate with a vertebra and the + articulation of the coracoids with the sternum. The humeral + articulation with the coracoid is unlike the condition shown + in other Ornithosaurs] + +There is no approach to this transverse position of the scapulae among +birds. And while the form of the bones in the older genera of +Ornithosaurs is singularly bird-like, the angular arrangement in this +Cretaceous genus is obtained by closely approximating the articulations +on the sternum, so that the coracoids extend outward as in reptiles, +instead of forward as in birds; and the extremities of the scapulae +similarly approximate towards each other. This rather recalls the +relative positions of scapula and coracoid among crocodiles. If +crocodile and bird had been primitive types of animals instead of +surviving types, it might almost seem as though there had been a cunning +and harmonious blending of one with the other in evolving this form of +shoulder-girdle. + + +THE FORE LIMB + +The bones of the fore limb, generally, correspond in length with the +similar parts of the hind limb. The upper arm bone corresponds with the +upper leg bone, and the fore-arm bone is as long as the fore-leg bone; +then differences begin. The bones which correspond to the back of the +hand in man, termed the metacarpus, are variable in length in +Pterodactyles--sometimes very long and sometimes short. The wing +metacarpal bone is always stout, and the others are slender. The +extremity of the metacarpus was applied to the ground. Three small +digits of the hand are developed from the three small metacarpal bones, +and terminate in large claws. + +The great wing finger was bent backward, and only touched the ground +where it fitted upon the wing metacarpal bone. It appears sometimes to +have been as long as the entire vertebral column. + +Owing to the circumstance that the joint in the arm in Pterodactyles was +not at the wrist as among birds, but between the metacarpus and the +phalanges, it follows that the fore limb was longer than the hind limb +when the metacarpus was long; but the difference would not interfere +with the movements of the animal, either upon four feet or on two feet, +for in bats and birds the disproportion in length is greater. + + +HUMERUS OR UPPER ARM BONE + +The first bone in the fore-arm, the humerus, is remarkable chiefly for +the compressed crescent form of its upper articular end, which is never +rounded like the head of the upper arm bone in man, and secondly for the +great development of the external process of bone near that end, termed +the radial crest. Sir Richard Owen compared the bone to the humerus of +both birds and crocodiles, but in its upper articular end the crocodile +bone may be said to be more like a bird than it is like the +Pterodactyle. In flying reptiles the articular surface next to the +shoulder-girdle is somewhat saddle-shaped, being concave from side to +side above and convex vertically, while most animals with which it can +be compared have the articular head of the bone convex in both +directions. A remarkable exception to this general rule is found in some +fossil animals from South Africa, which, from resemblance to mammals in +their teeth, have been termed Theriodonts. They sometimes have the head +of the bone concave from side to side and convex in the vertical +direction. To this condition Ornithorhynchus makes a slight +approximation. The singular expansion of the structure called the radial +crest finds no close parallel in reptiles, though Crocodiles have a +moderate crest on the humerus in the same position; and in Theriodonts +the radial crest extends much further down the shaft of the humerus. No +bird has a radial crest of a similar kind, though it is prolonged some +way down the shaft in Archaeopteryx. In Pterodactyles it sometimes +terminates outward in a smooth, rounded surface, which might have been +articular if any structure could have articulated with it. There is also +a moderate expansion of the bone on the ulnar side in some +Pterodactyles, so that the proximal end often incloses nearly +three-fourths of an ovate outline. The termination of the radial crest +is at the opposite end of this oval to the wider articular part of the +head of the bone, in some specimens from the Cambridge Greensand. The +radial crest is more extended in Rhamphorhynchus. All specimens of the +humerus show a twist in the length of the bone, so that the end towards +the fore-arm, which is wider than the shaft, makes a right angle with +the radial crest on the proximal end, which is not seen in birds. The +shaft of the humerus is always stouter than that of the femur, though +different genera differ in this respect. + +The humerus in genera from rocks associated with the Chalk presents two +modifications, chiefly seen in the characters of the distal end of the +bone. One of these is a stout bone with a curiously truncated end where +it joins the two bones of the fore-arm; and the other is more or less +remarkable for the rounded form of the distal condyles. Both types show +distinct articular surfaces. The inner one is somewhat oblique and +concave, the outer one rounded; the two being separated by a concave +channel, so that the ulna makes an oblique articulation with the bone as +in birds, and the radius articulates by a more or less truncated or +concave surface. + + [Illustration: FIG. 41. COMPARISON OF THE HUMERUS IN PTERODACTYLE AND + BIRD] + + +ULNA AND RADIUS + + [Illustration: FIG. 42. COMPARISON OF THE BONES OF THE FORE-ARM IN + BIRD AND ORNITHOSAUR] + +The bones of the fore-arm are similar to each other in size, and if +there be any difference between them the ulna is slightly the larger. +There is some evidence that in Rhamphorhynchus the upper end of the ulna +was placed behind the radius, probably in consequence of the mode of +attachment of those bones to the humerus. The ulna abutted towards the +inner and lower border, while the radius was towards the upper border, +consequent upon the twist in the humerus. This condition corresponds +substantially with the arrangement in birds, but differs from birds in +the relatively more important part taken by the radius in making the +articulation. The bones are compared in Dimorphodon with the Golden +Eagle drawn of the same size (Fig. 42). In birds the ulna supports the +great feathers of the wing, and this may account for the size of the +bone. The ulna is best seen at its proximal end in the specimens from +the Cambridge Greensand, where there is a terminal olecranon +ossification forming an oblique articulation, which frequently comes +away and is lost. It is sometimes well preserved, and indicated by a +suture. The examples of ulna from the Lias show a slight expansion of +the bone at both ends, and at the distal end toward the wrist the +articulation is well defined, where the bone joins the carpus. The +larger specimens of the bone are broken. The distal articular surface is +only connected with the proximal end of the bone in small specimens: it +always shows on the one margin a concavity, followed by a prominent +boss, and an oblique articulation beyond the boss. On the side towards +the radius, on the lower end of the shaft there is an angular ridge, +which marks the line along which the ulna overlaps the radius. The +lower end of the radius has a simple, slightly convex articulation, +somewhat bean-shaped. No rotation of these bones on each other was +possible as in man. There is a third bone in the fore-arm. This bone, +named the pteroid, is commonly seen in skeletons from Solenhofen. It was +regarded by Von Meyer as having supported the wing membrane in flight. +Some writers have interpreted it as an essential part of the +Pterodactyle skeleton, and Von Meyer thought that it might possibly +indicate a fifth digit in the hand. The only existing structure at all +like it is seen in the South African insectivorous mammal named +_Chrysochloris capensis_, the golden mole, which also has three bones in +the fore-arm, the third bone extending half-way up towards the humerus. +In that animal the third bone appears to be behind the others and +adjacent to the ulna. In the German fossils the pteroid articulated with +a separate carpal or metacarpal bone, placed on the side of the arm +adjacent to the radius, and the radius is always more inward than the +ulna. If the view suggested by Von Meyer is adopted, this bone would be +a first digit extending outward and backward towards the humerus. That +view was adopted by Professor Marsh. It involves the interpretation of +what has been termed the lateral carpal as the first metacarpal bone, +which would be as short as that of a bird, but turned in the opposite +direction backward. The first digit would then only carry one phalange, +and would not terminate in a claw, but lie in the line of the tendon +which supports the anterior wing membrane of a bird. + +The third bone in the fore-arm of Chrysochloris does not appear to +correspond to a digit. The bone is on the opposite side of the arm to +the similar bone of a Pterodactyle, and therefore cannot be the same +structure in the Golden Mole. The interpretation which makes the pteroid +bone the first digit has the merit of accounting for the fifth digit of +the hand. All the structures of the hand are consistent with this view. +The circumstance that the bone is rarely found in contact with the +radius, but diverging from it, shows that it plays the same part in +stretching the membrane in advance of the arm, that the fifth digit +holds in supporting the larger wing membrane behind the arm. + +According to Professor Williston, the American toothless Pterodactyle +Ornithostoma has but a single phalange on the corresponding first toe of +the hind foot, and that bone he describes as long, cylindrical, gently +curved, and bluntly pointed. There is some support for this +interpretation; but I have not seen any English or German Pterodactyles +with only one phalange in the first toe. + +The wing in Pterodactyles would thus be stretched between two fingers +which are bent backward, the three intermediate digits terminating in +claws. + + +THE CARPUS + +The wrist bones in the reptilia usually consist of two rows. In +Crocodiles, in the upper row there is a large inner and a small outer +bone, behind which is a lunate bone, the remainder of the carpus being +cartilaginous. Only one carpal is converted into bone in the lower row. +It is placed immediately under the smaller upper carpal. In Chelonians, +the turtle and tortoise group, the characters of the carpus vary with +the family. In the upper row there are usually two short carpals, which +may be blended, under the ulna; while the two under the radius are +commonly united. The lower row is made up of several small bones. +Lizards, too, usually have three bones in the proximal row and five +smaller bones in the distal row. + +The correspondence of the distal carpals with the several metacarpal +bones of the middle hand is a well-known feature of the structure of the +wrist. + +Von Meyer remarks that the carpus is made up of two rows of small bones +in the Solenhofen Pterodactyles; while in birds there is one row +consisting of two bones. The structure of the carpus is not distinct in +all German specimens; but in the short-tailed Solenhofen genera the +bones in the two rows retain their individuality. + +In all the Cretaceous genera the carpal bones of each row are blended +into a single bone, so that two bones are superimposed, which may be +termed the proximal and distal carpals. One specimen shows by an +indication of sutures the original division of the distal carpal into +three bones; and the separated constituent bones are very rarely met +with. Two bones of the three confluent elements contribute to the +support of the wing metacarpal, and the third gives an articular +attachment to the bone which extends laterally at the inner side of the +carpus, which I now think may be the first metacarpal bone turned +backward towards the humerus. The three component bones meet in the +circular pneumatic foramen in the middle of the under side of the distal +carpal. There is no indication of division of the proximal carpal in +these genera into constituent bones. + + [Illustration: FIG. 43. CARPUS FROM ORNITHOCHEIRUS + (Cambridge Greensand)] + +This condition is somewhat different from birds. In 1873 Dr. Rosenberg, +of Dorpat, showed that there is in the bird a proximal carpal formed of +two elements, and a distal carpal also formed of two elements. Therefore +the two constituents of the distal carpal in the bird which blends in +the mature animal with the metacarpus, forming the rounded pulley joint, +may correspond with two of the three bones in the Cretaceous +Pterodactyle _Ornithocheirus._ + +The width of a proximal carpal rarely exceeds two inches, and that of a +distal carpal is about an inch and three-quarters. Two such bones when +in contact would not measure more than one inch in depth. The lower +surface shows that the wing had some rotary movement upon the carpus +outward and backward. + + +METACARPUS + + [Illustration: FIG. 44. METACARPUS IN TWO ORNITHOSAURS] + +The metacarpus consists of bones which correspond to the back of the +hand. The first digit of the hand in clawed animals has the metacarpal +bone short, or shorter than the others. Among mammals metacarpal bones +are sometimes greatly elongated; and a similar condition is found in +Pterodactyles, in which the metacarpal bone may be much longer than the +phalange which is attached to it. Two metacarpal bones appear to be +singularly stouter than the others. The first bone of the first digit, +if rightly determined, is much shorter than the others, and is, in fact, +no longer than the carpus (Fig. 43). It is a flat oblong bone, attached +to the inner side of the lower carpal, and instead of being prolonged +distally in the same direction as the other metacarpal bones, is turned +round and directed upward, so that its upper edge is flush with the base +of the radius, and gives attachment to a bone which resembles a terminal +phalange of the wing finger. According to this interpretation it is the +first and only phalange in the first digit. The bone is often about half +as long as the fore-arm, terminates upward in a point, is sometimes +curved, and frequently diverges outward from the bones of the fore-arm, +as preserved in the associated skeleton, being stretched towards the +radial crest of the humerus. This mode of attachment of the supposed +first metacarpal, which is true for all Cretaceous pterodactyles, has +not been shown to be the same for all those from the Solenhofen Slate. +There is no greater anomaly in this metacarpal and phalange on the +inner side being bent backward, than there is in the wing finger being +bent backward on the outer side. The three slender intervening digits +extend forward between them, as though they were applied to the ground +for walking. + +The bone which is usually known as the wing metacarpal is frequently +stouter at the proximal end towards the carpus than towards the +phalange. At the carpal end it is oblong and truncated, with a short +middle process, which may have extended into the pit in the base of the +carpal bone; while the distal terminal end is rounded exactly like a +pulley. There is great difference in the length of the metacarpus. In +the American genus Ornithostoma it is much longer than the fore-arm. In +Rhamphorhynchus it is remarkably short, though perhaps scarcely so short +as in Dimorphodon or in Scaphognathus. The largest Cretaceous examples +are about two inches wide where they join the carpus. The bone is +sometimes a little curved. + +Between the first and fifth or wing metacarpal are the three slender +metacarpal bones which give attachment to the clawed digits. They bear +much the same relation to the wing metacarpal that the large metatarsal +of a Kangaroo has to the slender bones of the instep which are parallel +to it. + +The facet for the wing metacarpal on the carpus is clearly recognised, +but as a rule there is no surface with which the small metacarpals can +be separately articulated. One or two exceptional specimens from the +Cambridge Greensand appear to have not only surfaces for the wing +metacarpal, but two much smaller articular surfaces, giving attachment +to smaller metacarpals; while in one case there appears to be only one +of these additional impressions. It is certain that all the animals from +the Lias and Oolites have three clawed digits, but at present I have +seen no evidence that there were three in the Cretaceous genera, though +Professor Williston's statements and restoration appear to show that the +toothless Pterodactyles have three. Another difference from the Oolitic +types, according to Professor Williston, is in the length of the slender +metacarpals of the clawed phalanges being about one-third that of the +wing metacarpal, but this is probably due to imperfect ossification at +the proximal end; for at the distal end the bones all terminated on the +same level, showing that the four outer digits were applied to the +ground to support the weight of the body. The corresponding bone in the +Horse and Oxen is carried erect, so as to be in a vertical line with the +bones of the fore-arm; and the same position prevails usually, though +not invariably, with the corresponding bone in the hind limb, while in +many clawed mammals the metacarpus and metatarsus are both applied upon +the ground. In Pterodactyles the metatarsal bones are preserved in the +rock in the same straight line with the smaller bones of the foot, or +make an angle with the shin bone, leading to the conviction that the +bones of the foot were applied to the ground as in Man, and sometimes as +in the Dog, and were thus modified for leaping. Just as the human +metacarpus is extended in the same line with the bones of the fore-arm, +and the movement of jointing occurs where the fingers join the +metacarpus, so Pterodactyles also had these bones differently modified +in the fore and hind limbs for the functions of life. The result is to +lengthen the fore limb as compared with the hind limb by introducing +into it an elevation above the ground which corresponds to the length of +the metacarpus, always supposing that the animal commonly assumed the +position of a quadruped when upon the earth's surface. + +This position of the metacarpus is a remarkable difference from Birds, +because when the bird's wing is at rest it is folded into three +portions. The upper arm bone extends backward, the bones of the fore-arm +are bent upon it so as to extend forward, and then at the wrist the +third portion, which includes the metacarpus and finger bones, is bent +backward. So that the metacarpus in the Pterodactyle differs from birds +in being in the same line as the bones of the fore-arm, whereas in birds +it is in the same line with the digit bones of the hand. It is worthy of +remark that in Bats, which are so suggestive of Pterodactyles in some +features of the hand, the metacarpals and phalanges are in the same +straight line; so that in this respect the bat is more like the bird. +But Pterodactyles in the relation of these bones to flight are quite +unlike any other animal, and have nothing in common with the existing +animals named Reptiles. + + +THE HAND + +From what has just been said it follows that the construction of the +hand is unique. It may be contrasted with the foot of a bird. The bone +which is called, in the language of anatomists, the tarso-metatarsus, +and is usually free from feathers and covered with skin, is commonly +carried erect in birds, so that the whole body is supported upon it; and +from it the toes diverge outward. It is formed in birds of three +separate bones blended together. In the fore limb of the Pterodactyle +the metacarpus has the same relation to the bones of the fore-arm that +the metatarsus has to the corresponding bones of the leg in a bird. But +the three metacarpal bones in the Pterodactyle remain distinct from each +other, perhaps because the main work of that region of the skeleton has +devolved upon the digit called the wing finger, which is not recognised +in the bird. In the Pterodactyles from the Solenhofen Slate there is a +progressive number of phalanges in the three small digits of the hand, +which were applied to the ground. This number in the great majority of +species follows the formula of two bones in the first, three bones in +second, and four in the third; so that in the innermost of the clawed +digits only one bone intervenes between the metacarpal and the claw. The +fingers slightly increase in length with increase in number of bones +which form them. + + [Illustration: FIG. 45. CLAW PHALANGE FROM THE HAND IN + ORNITHOCHEIRUS. (Half natural size)] + + [Illustration: FIG. 46. METACARPUS AND DIGITS OF THE HAND IN BIRDS + WITH CLAWS] + +The terminal claw bones are unlike the claws of Birds or Reptiles. They +are compressed from side to side, and extremely deep and strong, with +evidence of powerful attachment for ligaments, so that they rather +resemble in their form and large size the claws of some of the +carnivorous fossil reptiles, often grouped as Dinosauria, such as have +been termed Aristosuchus and Megalosaurus. In the hand of the Ostrich +the first and second digits terminate in claws, while the third is +without a claw. But these claws of the Ostrich and other birds are +slender, curved, and rather feeble organs. In the Archaeopteryx, a fossil +bird which agrees with the Pterodactyles in retaining the separate +condition of the metacarpal bones and in having the same number of +phalanges in two of the fingers of the fore limb, the terminal claws are +rather more compressed from side to side, and stronger than in the +Ostrich, but not nearly so strong as in the Pterodactyle. The +Archaeopteryx differs from the Pterodactyle in having no trace of a wing +finger. The first metacarpal bone is short, as in all birds; and the +first phalange scarcely lengthens that segment of the first digit of the +Bird's hand to the same length as the other metacarpal bones. It +therefore was not bent backward like the first digit in Pterodactyles. +The wing finger, from which the genius of Cuvier selected the scientific +name--Pterodactyle--for these fossils, yields their most distinctive +character. It is a feature which could only be partly paralleled in the +Bat, by making changes of structure which would remove every support to +the wing but the outermost digit of that animal's hand. In the Bat's +hand the membrane for flight is extended chiefly by four diverging +metacarpal bones. There are only two or three phalanges in each digit in +its four wing fingers. In Pterodactyles the metacarpal bones are, as we +have seen, arranged in close contact, and take no part in stretching the +wing. + + +THE WING FINGER + +In Birds there is nothing whatever to represent the wing finger of the +Pterodactyle, for it is an organ external to the finger bones of the +bird, and contains four phalanges. The first phalange is quite different +from the others. Its length is astonishing when compared with the small +phalanges of the clawed fingers. The articular surface, which joins on +to the wing metacarpal bone, is a concave articulation, which fits the +pulley in which that bone ends. The pulley articulation admits of an +extension movement in one direction only. Many specimens show the wing +finger to be folded up so as to extend backward. The whole finger is +preserved in other specimens straightened out so as to be in line with +the metacarpus. This condition is well seen in Professor Marsh's +specimen of Rhamphorhynchus, which has the wing membrane preserved, in +which all bones of the fore-arm metacarpus and wing finger are extended +in a continuous curve. The outer surface of the end of the first bone of +the wing finger overlaps the wing metacarpal, so that a maximum of +strength and resistance is provided in the bony structures by which the +wing is supported. There is, therefore, in flight only one angular bend +in the limb, and that is between the upper arm bone and the fore-arm. + +An immense pneumatic foramen is situate in a groove on the under side of +the upper end of the first phalange in Ornithocheirus, but is absent in +specimens from the Kimeridge clay. This bone is long and stout. It +terminates at the lower end in an obliquely truncated articular surface. +Specimens occur in the Cambridge Greensand which are 2 inches broad at +the upper end and nearly 1-1/2 inch wide at the lower end. An imperfect +bone from the Chalk is 14-1/2 inches long. The bones are all flattened. +Specimens from the Chalk of Kansas at Munich are 28 inches long. The +second phalange is concave at the upper articular end and convex in the +longer direction at the lower end. The articular points of union between +the several phalanges form prominences on the under side of the finger +in consequence of the adjacent bones being a little widened at their +junction. It should be mentioned that there is a proximal epiphysis or +separate bone to the first phalange, adjacent to the pulley joint of the +metacarpal bone, which is like the separate olecranon process of the +ulna of the fore-arm. It sometimes comes away in specimens from the +Chalk and Cambridge Greensand, leaving a large circular pit with a +depressed narrow border. On the outer side of this process is a rounded +boss, which may possibly have supported the bone, if it were applied to +the ground with the wing folded up, like the wing of a Bat directed +upward and backward at the animal's side. + +The four bones of the wing finger usually decrease progressively in +length, so that in Rhamphorhynchus, in which the length of the animal's +head only slightly exceeds 3-1/2 inches, the first phalange is nearly as +long, the second phalange is about 3-1/4 inches, the third 2-3/4 inches, +and the fourth a little over 2 inches. Thus the entire length of the +four phalanges slightly exceeds 11 inches, or rather more than three +times the length of the head. But the fore-arm and metacarpus in this +type only measure 3 inches. Therefore the entire spread of wings could +not have been more than 2 feet 9 inches. + +The largest Ornithosaur in which accurate measurements have been made is +the toothless Pterodactyle Ornithostoma, also named Pteranodon, from +North America. In that type the head appears to have been about 3 or 4 +feet long, and the wing finger exceeded 5 feet; while the length of the +fore-arm and metacarpus exceeded 3 feet. The width of the body would not +have been more than 1 foot. The length of the short humerus, which was +about 11 inches, did not add greatly to the stretch of the wing; so that +the spread of the wings as stretched in flight may be given as probably +not exceeding 17 or 18 feet. A fine example of the wing bones of this +animal quite as large has been obtained by the (British Museum Natural +History). Many years ago, on very fragmentary materials, I estimated the +wings in the English Cretaceous Ornithocheirus as probably having a +stretch of 20 feet in the largest specimens, basing the calculation +partly upon the extent of the longest wings in existing birds relatively +to their bones, and partly upon the size of the largest associated bones +which were then known. + + + + +CHAPTER XII + +EVIDENCES OF THE ANIMAL'S HABITS FROM ITS REMAINS + + +Such are the more remarkable characters of the bones in a type of animal +life which was more anomalous than any other which peopled the earth in +the Secondary Epoch of geological time. Its skeleton in different parts +resembles Reptiles, Birds, and Mammals; with modifications and +combinations so singular that they might have been deemed impossible if +Nature's power of varying the skeleton could be limited. Since +Ornithosaurs were provided with wings, we may believe the animals to +some extent to have resembled birds in habit. Their modes of progression +were more varied, for the structures indicate an equal capacity for +movement on land as a biped, or as a quadruped, with movement in the +air. There is little evidence to support the idea that they were usually +aquatic animals. The majority of birds which frequent the water have +their bodies stored with fat and the bones of their extremities filled +with marrow. And a bird's marrow bones are stouter and stronger than +those which are filled with air. There are few, if any, bones of +Pterodactyles so thick as to suggest the conclusion that they contained +marrow, and the bones of the extremities appear to have been +constructed on the lightest type found among terrestrial birds. Their +thinness, except in a few specimens from the Wealden rocks, is +marvellous; and all the later Pterodactyles show the arrangement, as in +birds, by which air from the lungs is conveyed to the principal bones. +No Pterodactyle has shown any trace of the web-footed condition seen in +birds which swim on the water, unless the diverging bones of the hind +foot in Rhamphorhynchus supports that inference. The bones of the hind +foot are relatively small, and if it were not that a bird stands easily +upon one foot, might be considered scarcely adequate to support the +animal in the position which terrestrial birds usually occupy. Yet, as +compared with the length and breadth of the foot in an Ostrich, the toes +of an Ornithosaur are seen to be ample for support. These facts appear +to discourage the idea that the animals were equally at home on land and +water, and in air. + +Some light may be thrown upon the animal's habits by the geological +circumstances under which the remains are found. The Pterodactyle named +Dimorphodon, from the Lias of the south of England, is associated with +evidences of terrestrial land animals, the best known of which is +Scelidosaurus, an armoured Dinosaur adapted by its limbs for progression +on land. And the Pterodactyle Campylognathus, from the Lias of Whitby, +is associated with trunks of coniferous trees and remains of Insects. So +that the occurrence of Pterodactyles in a marine stratum is not +inconsistent with their having been transported by streams from off the +old land surface of the Lias, on which coniferous trees grew and +Dinosaurs lived. + +Similar considerations apply to the occurrence of the Rhamphocephalus in +the Stonesfield Slate of England. The deposit is not only formed in +shallow water, but contains terrestrial Insects, a variety of land +plants, and many Reptiles and other animals which lived upon land. The +specimens from the Purbeck beds, again, are in strata which yield a +multitude of the spoils of a nearly adjacent land surface; while the +numerous remains found in the marine Solenhofen Slate in Germany are +similarly associated with abundant evidences of varied types of +terrestrial life. The evidence grows in force from its cumulative +character. The Wealden beds, which yield many terrestrial reptiles and +so much evidence of terrestrial vegetation, and shallow-water conditions +of disposition, have afforded important Pterodactyle remains from the +Isle of Wight and Sussex. + +The chief English deposit in which these fossils are found, the Upper +Greensand, has afforded thousands of bones, battered and broken on a +shore, where they have lain in little associated groups of remains, +often becoming overgrown with small marine shells. Side by side with +them are found bones of true terrestrial Lizards and Crocodiles of the +type of the Gavial of the Indian rivers, many terrestrial Dinosaurs, and +other evidences of land life, including fossil resins, such as are met +with in the form of amber or copal at the present day. + +The great bones of Pterodactyles found in the Chalk of Kent, near +Rochester, became entombed, beyond question, far from a land surface. +There is nothing to show whether the animals died on land and were +drifted out to sea like the timber which is found water-logged and +sunken after being drilled by the ship-worm (Teredo) of that epoch. +Seeing the power of flight which the animal possessed, storms may have +struck down travellers from time to time, when far from land. + +Evidence of habit of another kind may be found in their teeth. They are +brightly enamelled, sharp, formidable; and are frequently long, +overlapping the sides of the jaws. They are organs which are often +better adapted for grasping than for tearing, as may be seen in the +inclined teeth of Rhamphocephalus of the Stonesfield Slate; and better +adapted for killing than tearing, from their piercing forms and cutting +edges, in genera like Ornithocheirus of the Greensand. The manner in +which the teeth were implanted and carried is better paralleled by the +fish-eating crocodile of Indian rivers than by the flesh-eating +crocodiles, or Muggers, which live indifferently in rivers and the sea. +As the Kingfisher finds its food (see Fig. 20) from the surface of the +water without being in the common sense of the term a water bird, so +some Pterodactyles may have fed on fish, for which their teeth are well +adapted, both in the stream and by the shore. + +A Pterodactyle's teeth vary a good deal in appearance. The few large +teeth in the front of the jaw in Dimorphodon, associated with the many +small vertical teeth placed further backward, suggest that the taking of +food may have been a process requiring leisure, since the hinder teeth +adapted to mincing the animal's meat are extremely small. The way in +which the teeth are shaped and arranged differs with the genera. In +Pterodactylus they are short and broad and few, placed for the most part +towards the front of the jaws. Their lancet-shaped form indicates a +shear-like action adapted to dividing flesh. In the associated genus +Rhamphorhynchus the teeth are absent from the extremity of the jaw, are +slender, pointed, spaced far apart, and extend far backward. When the +jaws of the Rhamphorhynchus are brought together there is always a gap +between them in front, which has led to belief that the teeth were +replaced by some kind of horny armature which has perished. In the +long-nosed English type of Ornithocheirus the jaws are compressed +together, so that the teeth of the opposite sides are parallel to each +other, with the margins well filled with teeth, which are never in close +contact, though occasionally closer and larger in front, in some of the +forms with thick truncated snouts. + +It is not the least interesting circumstance of the dentition of +Pterodactyles that, associated in the same deposits with these most +recent genera with teeth powerfully developed, there is a genus named +Ornithostoma from the resemblance of its mouth to that of a bird in +being entirely devoid of teeth. It is scarcely possible to distinguish +the remains of the toothed and toothless skeletons except in the dentary +character of the jaws. There is no evidence that the toothless types +ever possessed a tooth of any sort. They were first found in fragments +in England in the Cambridge Greensand, but were afterwards met with in +great abundance in the Chalk of Kansas, where the same animals were +named Pteranodon. A jaw so entirely bird-like suggests that the +digestive organs of Pterodactyles may in such toothless forms at least +have been characterised by a gizzard, which is so distinctive of Birds. +The absence of teeth in the Great Ant-eater and some other allied +Mammals has transferred the function which teeth usually perform to the +stomach, one part of which becomes greatly thickened and muscular, +adapting itself to the work which it has to perform. It is probable that +the gizzard may be developed in relation to the necessities which food +creates, since even Trout, feeding on the shell-fish in some Irish +lochs, acquire such a thickened muscular stomach, and a like +modification is recorded in other fishes as produced by food. + +Closely connected with an animal's habits is the protection to the body +which is afforded by the skin. In Pterodactyles the evidence of the +condition of the skin is scanty, and mostly negative. Sometimes the +dense, smooth texture of the jaw bones indicates a covering like the +skin of a Lizard or the hinder part of the jaw of a Bird. Some jaws from +the Cambridge Greensand have the bone channeled over its surface by +minute blood vessels which have impressed themselves into the bone more +easily than into its covering. Thus in the species of Ornithocheirus +distinguished as _microdon_ the palate is absolutely smooth, while in +the species named _machaerorhynchus_ it is marked by parallel impressed +vascular grooves which diverge from the median line. This condition +clearly indicates a difference in the covering of the bone, and that in +the latter species the covering had fewer blood vessels and more horny +protection than in the other. The tissue may not have been of firmer +consistence than in the palate of Mammals. The extremity of the beak is +often as full of blood vessels as the jaw of a Turtle or Crocodile. + + +COVERING OF THE BODY + +There is no trace even in specimens from the Solenhofen or Stonesfield +Slate of any covering to the body. There are no specimens preserved like +mummies, and although the substance of the wings is found there is no +trace of fur or feathers, bones, or scales on the skin. The only example +in which there is even an appearance suggesting feathers is in the +beautiful Scaphognathus at Bonn, and upon portions of the wing membrane +of that specimen are preserved a very few small short and apparently +tubular bodies, which have a suggestive resemblance to the quills of +small undeveloped feathers. Such evidences have been diligently sought +for. Professor Marsh, after examining the wing membranes of his specimen +of Rhamphorhynchus from Solenhofen, stated that the wings were partially +folded and naturally contracted into folds, and that the surface of the +tissue is marked by delicate striae, which might easily be taken at first +sight for a thin coating of hair. Closer investigation proved the +markings to be minute wrinkles on the under surface of the wing +membrane. This negative evidence has considerable value, because the +Solenhofen Slate has preserved in the two known examples of the bird +Archaeopteryx beautiful details of the structure of the larger feathers +concerned in flight. It has preserved many structures far more delicate. +There is, therefore, reason for believing that if the skin had possessed +any covering like one of those found in existing vertebrate animals, it +could scarcely have escaped detection in the numerous undisturbed +skeletons of Pterodactyles which have been examined. + +The absence of a recognisable covering to the skin in a fossil state +cannot be accepted as conclusive evidence of the temperature, habits, or +affinities of the animal. Although Mammalia are almost entirely clothed +with dense hair, which has never been found in a recognisable condition +in a fossil state in any specimen of Tertiary age, one entire order, the +Cetacea, show in the smooth hairless skins of Whales and Porpoises that +the class may part with the typical characteristic covering without loss +of temperature and without intelligible cause. That the absence of hair +is not due to the aquatic conditions of rivers or sea is proved by other +marine Mammals, like Seals, having the skin clothed with a dense growth +of hair, which is not surpassed in any other order. The fineness of the +growth of hair in Man gives a superficial appearance of the skin being +imperfectly clothed, and a similar skin in a fossil state might give the +impression that it was devoid of hair. There are many Mammals in which +the skin is scantily clothed with hair as the animal grows old. Neither +the Elephant nor the Armadillo in a fossil state would be likely to have +the hair preserved, for the growth is thin on the bony shields of the +living Armadilloes. Yet the difficulty need be no more inherent in the +nature of hair than in that of feathers, since the hair of the Mammoth +and Rhinoceros has been completely preserved upon their skins in the +tundras of Siberia, densely clothing the body. This may go to show that +the Pterodactyle possessed a thin covering of hair, or, more probably, +that hair was absent. Since Reptiles are equally variable in the +clothing of the skin with bony or horny plates, and in sometimes having +no such protection, it may not appear singular that the skin in +Ornithosaurs has hitherto given no evidence of a covering. From analogy +a covering might have been expected; feathers of Birds and hair of +Mammals are non-conducting coverings suited to arrest the loss of heat. + +With the evidence, such as it is, of resemblance of Ornithosaurs to +Birds in some features of respiration and flight, a covering to the skin +might have been expected. Yet the covering may not be necessary to a +high temperature of the blood. Since Dr. John Davy made his observations +it has been known that the temperature of the Tunny, above 90 deg. +Fahrenheit, is as warm as the African scaly ant-eater named the +Pangolin, which has the body more amply protected by its covering. This +illustration also shows that hot blood may be produced without a +four-celled heart, with which it is usually associated, and that even if +the skin in Pterodactyles was absolutely naked an active life and an +abundant supply of blood could have given the animal a high temperature. + +The circumstance that in several individuals the substance of the wing +membrane is preserved would appear to indicate either that it was +exceptionally stout when there would have been small chance of resisting +decomposition, or that its preservation is due to a covering which once +existed of fur or down or other clothing substance, which has proved +more durable than the skin itself. + + [Illustration: FIG. 48. REMAINS OF DIMORPHODON FROM THE LIAS OF LYME + REGIS + + SHOWING THE SKULL, NECK, BACK AND SOME OF THE LONGER BONES OF THE + SKELETON + + _From a slab in the British Museum (Natural History)_] + + + + +CHAPTER XIII + +ANCIENT ORNITHOSAURS FROM THE LIAS + + +Cuvier's discourse on the revolutions of the Earth made the Pterodactyle +known to English readers early in the nineteenth century. Dr. Buckland, +the distinguished professor of Geology at Oxford, discovered in 1829 a +far larger specimen in the Lias of Lyme Regis, and it became known by a +figure published by the Geological Society, and by the description in +his famous Bridgewater Treatise, p. 164. This animal was tantalising in +imperfect preservation. The bones were scattered in the clay, so as to +give no idea of the animal's aspect. Knowledge of its limbs and body has +been gradually acquired; and now, for some years, the tail and most +parts of the skeleton have been well known in this oldest and most +interesting British Pterodactyle. + +Sir Richard Owen after some time separated the fossil as a distinct +genus, named Dimorphodon; for it was in many ways unlike the +Pterodactyles described from Bavaria. The name Dimorphodon indicated the +two distinct kinds of teeth in the jaws, a character which is still +unparalleled among Pterodactyles of newer age. There are a few large +pointed, piercing and tearing teeth in the front of the jaws, with +smaller teeth further back, placed among the tearing teeth in the upper +jaw; while in the lower jaw the small teeth are continuous, close-set, +and form a fine cutting edge like a saw. + + [Illustration: FIG. 49. LEFT SIDE OF DIMORPHODON (RESTORED) AT REST] + +The Dimorphodon has a short beak, a deep head, and deep lower jaw, which +is overlapped by the cheek bones. The side of the head is occupied by +four vacuities, separated by narrow bars of bone. First, in front, is +the immense opening for the nostril, triangular in form, with the long +upper side following the rounded curve of the face. A large triangular +opening intervenes between the nose hole and the eye hole, scarcely +smaller than the former, but much larger than the orbit of the eye. The +eye hole is shaped like a kite or inverted pear. Further back still is a +narrower vertical opening known as the lateral or inferior temporal +vacuity. The back of the head is badly preserved. The two principal +skulls differ in depth, probably from the strains under which they were +pressed flat in the clay. A singular detail of structure is found in the +extremity of the lower jaw, which is turned slightly downward, and +terminates in a short toothless point. The head of Dimorphodon is +about eight inches long. + + [Illustration: FIG. 50. DIMORPHODON MACRONYX + RESTORED FORM OF THE ANIMAL] + +The neck bones are of suitable stoutness and width to support the head. +The bones are yoked together by strong processes. The neck was about 6 +inches long, did not include more than seven bones, and appeared short +owing only to the depth and size of the head. The length of the backbone +which supported the ribs was also about 6 inches. Its joints are +remarkably short when compared with those of the neck. The tail is about +20 inches long. + +The extreme length of the animal from the tip of the nose to the end of +the tail may have been 3 feet 4 inches, supposing it to have walked on +all fours in the manner of a Reptile or Mammal. This may have been a +common position, but Dimorphodon may probably also have been a biped. +Before 1875, when the first restoration appeared in the _Illustrated +London News_, the legs had been regarded as too short to have supported +the animal, standing upon its hind limbs. They are here seen to be well +adapted for such a purpose. The upper leg bone is 3-1/4 inches long, the +lower leg bone is 4-1/2 inches long, and the singularly strong instep +bones are firmly packed together side by side as in a leaping or jumping +Mammal, and measure 1-1/2 inches in length. Dimorphodon differs from +several other Pterodactyles in having the hind limb provided with a +fifth outermost short instep bone, to which two toe bones are attached. +These bones are elongated in a way that may be compared, on a small +scale, with the elongation of the wing finger in the fore limb. The +digit was manifestly used in the same way as the wing finger, in partial +support of a flying membrane, though its direction may have been upward +and outward, rather than inward. There is no evidence of a pulley joint +between the metatarsal and the adjacent phalange. + +The height of the Dimorphodon, standing on its hind legs in the position +of a Bird, with the wings folded upon the body in the manner of a Bird, +was about 20 inches. An ungainly, ill-balanced animal in aspect, but not +more so than many big-headed birds, and probably capable of resting upon +the instep bones as many birds do. The chief point of variation from the +Pterodactyle wing is in the relative length of the metacarpus in +Dimorphodon. It is shorter than the other bones in the wing, never +exceeding 1-1/2 inches. The total length of all the arm bones down to +the point where the metacarpus might have touched the ground, or where +the wing finger is bent upon it, is about 9 inches, which gives a length +of less than 6 inches below the upper arm bone. The four bones of the +wing finger measure, from the point where the first bone bends upon the +metacarpus, less than 18 inches. So that the wings could only have been +carried in the manner of the wings of a Bat, folded at the side and +directed obliquely over the back when the animal moved on all fours. Its +body would appear to have been raised high above the ground, in a manner +almost unparalleled in Reptiles, and comparable to Birds and Mammals. +Dimorphodon is to be imagined in full flight, with the body extended +like that of a Bird, when the wings would have had a spread from side to +side of about 4 feet 4 inches. As in other animals of this group, the +three claws on the front feet are larger than the similar four claws on +the hind feet; as though the fingers might have functions in grasping +prey, which were not shared by the toes. + + [Illustration: FIG. 51. DIMORPHODON MACRONYX WALKING AS A QUADRUPED + RESTORATION OF THE SKELETON] + +The restorations give faithful pictures of the skeleton, and the form of +the body is built upon the indications of muscular structure seen in the +bones. + +A second English Pterodactyle is found in the Upper Lias of Whitby. It +is only known from an imperfect skull, published in 1888. It has the +great advantage of preserving the bones in their natural relations to +each other, and with a length of head probably similar to Dimorphodon +shows that the depth at the back of the eye was much less; and the skull +wants the arched contour of face seen in Dimorphodon. The head has the +same four lateral vacuities, but the nostril is relatively small and +elongated, extending partly above the oval antorbital opening, which was +larger. There is thus a difference of proportion, but it is precisely +such as might result from the species having the skull flatter. The head +is easily distinguished by the small nostril, which is smaller than the +orbit of the eye. The animal is referred to another genus. The quadrate +bones which give attachment to the lower jaw send a process inward to +meet the bones of the palate, which differ somewhat from the usual +condition. Two bony rods extend from the quadrate bones backward and +upward to the sphenoid, and two more slender bones extend from the +quadrate bones forward, and converge in a #V#-shape, to define the +division between the openings of the nostrils on the palate. The +#V#-shaped bone in front is called the vomer, while the hinder part is +called pterygoid. The bones that extend backward to the sphenoid are not +easily identified. This animal is one of the most interesting of +Pterodactyles from the very reptilian character exhibited in the back of +the head, which appears to be different from other specimens, which are +more like a bird in that region. Yet underneath this reptilian aspect, +with the bony bar at the side of the temporal region of the head formed +by the squamosal and quadrate bones, defining the two temporal vacuities +as in Reptiles, a mould is preserved of the cavity once occupied by the +brain, showing the chief details of structure of that organ, and proving +that in so far as it departs from the brain of a Bird it appears to +resemble the brain of a Mammal, and is unlike the brain of a Reptile. + +The Pterodactyles from the Lias of Germany are similar to the English +types, in so far as they can be compared. In 1878 I had the opportunity +of studying those which were preserved in the Castle at Banz, which +Professor Andreas Wagner, in 1860, referred to the new genus +Dorygnathus. The skull is unknown, but the lower jaw, 6-1/2 inches long, +is less than 2-1/2 inches wide at the articulation with the quadrate +bone in the skull. The depth of the lower jaw does not exceed 1/4 inch, +so that it is in marked contrast to Buckland's Dimorphodon. The +symphysis, which completely blends the rami of the jaw, is short. As far +as it extends it contains large tearing teeth, followed by smaller teeth +behind, like those of Dimorphodon. But this German fossil appears to +differ from the English type in having the front of the lower jaw, for +about 3/4 inch, compressed from side to side into a sharp blade or +spear, more marked than in any other Pterodactyle, and directed _upward_ +instead of downward as in Dimorphodon. Nearly all the measurements in +the skeleton are practically identical with those of the English +Dimorphodon, and extend to the jaw, humerus, ulna and radius, wing +metacarpal, first phalange of the wing finger. The principal bones of +the hind limb appear to be a little shorter; but the scapula and +coracoid are slightly larger. All these bones are so similar in form to +Dimorphodon that they could not be separated from the Lyme Regis +species, if they were found in the same locality. + + [Illustration: FIG. 52. DIMORPHODON MACRONYX WALKING AS A BIPED + _Based chiefly on remains in the British Museum_] + + [Illustration: FIG. 53. LOWER JAW OF DORYGNATHUS SEEN FROM BELOW + + From the Lower Lias of Germany, showing the spear in front of the + tooth sockets] + +Just as the Upper Lias in England has yielded a second Pterodactyle, so +the Upper Lias in Germany has yielded a skeleton, to which Felix +Plieninger, in 1894, gave the name Campylognathus. It is an instructive +skeleton, with the head much smaller than in Dimorphodon, being less +than 6 inches long, but, unfortunately, broken and disturbed. A lower +jaw gives the length 4-1/2 inches. Like the other Pterodactyles from +the Lias, it has the extremity of the beak toothless, with larger teeth +in the region of the symphysis in front and smaller teeth behind. The +jaw is deeper than in the Banz specimen from the Lower Lias, but not so +deep as in Dimorphodon. The teeth of the upper jaw vary in size, and +there appears to be an exceptionally large tooth in the position of the +Mammalian canine at the junction of the bones named maxillary and +intermaxillary. + +The nasal opening is small and elongated, as in the English specimen +from Whitby. As in that type there is little or no indication of the +convex contour of the face seen in Dimorphodon. + +The neck does not appear to be preserved. In the back the vertebrae are +about 3/10 inch long, so that twelve, which is the usual number, would +only occupy a length of a little more than 3-1/2 inches. The tail is +elongated like that of Dimorphodon, and bordered in the same way by +ossified ligaments. There are thirty-five tail vertebrae. Those which +immediately follow the pelvis are short, like the vertebrae of the back. +But they soon elongate, and reach a maximum length of nearly 1-1/2 +inches at the eighth, and then gradually diminish till the last scarcely +exceeds 1/8 inch in length. The length of the tail is about 22 inches; +this appears to be an inch or two longer than in Dimorphodon. The +longest rib measures 2-1/2 inches, and the shortest 2 inches. These ribs +probably were connected with the sternum, which is imperfectly +preserved. + + [Illustration: FIG. 54. DIMORPHODON MACRONYX + SHOWING THE MAXIMUM SPREAD OF THE WING MEMBRANES] + +The bones of the limbs have about the same length as those of +Dimorphodon, so far as they can be compared, except that the ulna and +radius are shorter. The wing metacarpal is of about the same length, but +the first phalange of the wing finger measures 6-1/4 inches, the second +is about 8-1/4 inches, the third 6-1/2 inches, and the fourth 4-3/4 +inches; so that the total length of the wing finger was about half an +inch short of 2 feet. One character especially deserves attention in the +apparent successive elongation of the first three phalanges in the wing +finger in Dimorphodon. The third phalange is the longest in the only +specimen in which the finger bones are all preserved. Usually the first +phalange is much longer than the second, so that it is a further point +of interest to find that this German type shares with Dimorphodon a +character of the wing finger which distinguishes both from some members +of the group by its short first phalange. + + [Illustration: FIG. 55. THE LEFT SIDE OF THE PELVIS OF DIMORPHODON + SHOWING THE TWO PREPUBIC BONES] + +The pelvis is exceptionally strong in Campylognathus, and although it is +crushed the bones manifestly met at the base of the ischium, while the +pubic bones were separated from each other in front. The bones of the +hind limb are altogether shorter in the German fossil than in +Dimorphodon, especially in the tibia; but the structure of the +metatarsus is just the same, even to the short fifth metatarsal with its +two digits, only those bones are extremely short, instead of being +elongated as in Dimorphodon. It is therefore convenient, from the +different proportions of the body, that Campylognathus may be separated +from Dimorphodon; but so much as is preserved of the English specimen +from the Upper Lias of Whitby rather favours the belief that our species +should also be referred to Campylognathus, which had not been figured +when the Whitby skull was referred to Scaphognathus by Mr. Newton. It +may be doubtful whether there is sufficient evidence to establish the +distinctness of the other German genus Dorygnathus, though it may be +retained pending further knowledge. + +In these characters are grounds for placing the Lias Pterodactyles in a +distinct family, the Dimorphodontidae, as was suggested in 1870. This +evidence is found in the five metatarsal bones, of which four are in +close contact, the middle two being slightly the longest, so as to +present the general aspect of the corresponding bones in a Mammal rather +than a Bird. Secondly, the very slender fibula, prolonged down the +length of the shin bone, which ends in a rounded pulley like the +corresponding bone of a Bird. Thirdly, the great elongation of the third +wing phalange. Fourthly, the prolongation of the coracoid bone beyond +the articulation for the humerus, as in a Bird. And the toothless, +spear-shaped beak, and jaw with large teeth in front and small teeth +behind, are also distinctive characters. + + + + +CHAPTER XIV + +ORNITHOSAURS FROM THE MIDDLE SECONDARY ROCKS + + +RHAMPHOCEPHALUS + +THE Stonesfield Slate in England, which corresponds in age with the +lower part of the Great or Bath Oolite, yields many evidences of +terrestrial life--land plants, insects, and mammals--preserved in a +marine deposit. A number of isolated bones have been found of +Pterodactyles, some of them indicating animals of considerable size and +strength. The nature of the limestone was unfavourable to the +preservation of soft wing membranes, or even to the bones remaining in +natural association. Very little is known of the head of +Rhamphocephalus. One imperfect specimen shows a long temporal region +which is wide, and a very narrow interspace between the orbits; with a +long face, indicated by the extension of narrow nasal bones. The lower +jaw has an edentulous beak or spear in front, which is compressed from +side to side in the manner of the Liassic forms, but turned upward +slightly, as in Dorygnathus or Campylognathus. Behind this extremity are +sharp, tall teeth, few in number, which somewhat diminish in size as +they extend backward, and do not suddenly change to smaller series, as +in the Lias genera. A few small vertebrae have been found, indicating the +neck and back. The sacrum consists of five vertebrae. One small example +has a length of only an inch. It is a little narrower behind than in +front, and would be consistent with the animal having had a long tail, +which I believe to have been present, although I have not seen any +caudal vertebrae. The early ribs are like the early ribs of a Crocodile +or Bird in the well-marked double articulation. The later ribs appear to +have but one head. #V#-shaped abdominal ribs are preserved. Much of the +animal is unknown. The coracoid seems to have been directed forward, +and, as in a bird, it is 2-1/2 inches long. The humerus is 3-1/2 inches +long, and the fore-arm measured 6 inches, so that it was relatively +longer than in Dimorphodon. The metacarpus is 1-3/4 inches long. The +wing finger was exceptionally long and strong. Professor Huxley gave its +length at 29 inches. My own studies lead to the conclusion that the +first finger bone of the wing was the shorter, and that although they +did not differ greatly in length, the second was probably the longest, +as in Campylognathus. + +Professor Huxley makes the second and third phalanges 7-3/4 inches long, +and the first only about 3/8 inch shorter, while the fourth phalange is +6-1/2 inches. These measurements are based upon some specimens in the +Oxford University Museum. There is only one first phalange which has a +length of 7-3/4 inches. The others are between 5 and 6 inches, or but +little exceed 4 inches; so that as all the fourth phalanges which are +known have a length of 6-1/2 inches, it is possible that the normal +length of the first phalange in the larger species was 5-1/2 inches. The +largest of the phalanges which may be classed as second or third is +8-1/2 inches, and that, I suppose, may have been associated with the +7-3/4 inches first phalange. But the other bones which could have had +this position all measure 5-1/2 and 7-3/4 inches. The three species +indicated by finger bones may have had the measurements:-- + + Phalanges of the wing finger + ________________/\________________ + | | + I. II. III. IV. + 7-3/4 8-1/2 [7?] 6-1/2 } length of each bone + 5-1/2 7-3/4 5-1/2 [4-1/2?] } in inches. + 4-1/2 ---- ---- ---- } + +The femur is represented by many examples--one 3-3/4 inches long, and +others less than 3 inches long (2-9/10). In Campylognathus, which has so +much in common with the jaw and the wing bones in size, the upper leg +bone is 2-8/10 inches. Therefore if we assign the larger femur to the +larger wing, the femur will be relatively longer in all species of +Rhamphocephalus than in Campylognathus. Only one example of a tibia is +preserved. It is 3-1/2 inches long, or only 1/10 inch shorter than the +bone in Campylognathus, which has the femur 2-8/10 inches, so that I +refer the tibia of Rhamphocephalus to the species which has the +intermediate length of wing. These coincidences with Campylognathus +establish a close affinity, and may raise the question whether the Upper +Lias species may not be included in the Stonesfield Slate genus +Rhamphocephalus. + +The late Professor Phillips, in his _Geology of Oxford_, attempted a +restoration of the Stonesfield Ornithosaur, and produced a picturesque +effect (p. 164); but no restoration is possible without such attention +to the proportions of the bones as we have indicated. + + +OXFORD CLAY + +A few bones of flying reptiles have been found in the Lower Oxford Clay +near Peterborough, and others in the Upper Oxford Clay at St. Ives, in +Huntingdonshire. A single tail vertebra from the Middle Oxford Clay, +near Oxford, long since came under my own notice, and shows that these +animals belong to a long-tailed type like Campylognathus. The cervical +vertebrae are remarkable for being scarcely longer than the dorsal +vertebrae; and the dorsal are at least half as long again as is usual, +having rather the proportion of bones in the back of a crocodile. + + +LITHOGRAPHIC SLATE + +Long-tailed Pterodactyles are beautifully preserved in the Lithographic +Limestone of the south of Bavaria, at Solenhofen, and the quarries in +its neighbourhood, often with the skeleton or a large part of it +flattened out in the plane of bedding of the rock. Fine skeletons are +preserved in the superb museum at Munich, at Heidelberg, Bonn, Haarlem, +and London, and are all referred to the genus Rhamphorhynchus or to +Scaphognathus. It is a type with powerfully developed wings and a long, +stiff tail, very similar to that of Dimorphodon, so that some +naturalists refer both to the same family. There is some resemblance. + +The type which is most like Dimorphodon is the celebrated fossil at +Bonn, sometimes called _Pterodactylus crassirostris_, which in a +restored form, with a short tail, has been reproduced in many +text-books. No tail is preserved in the slab, and I ventured to give the +animal a tail for the first time in a restoration (p. 163) published by +the _Illustrated London News_ in 1875, which accompanied a report of a +Royal Institution lecture. Afterwards, in 1882, Professor Zittel, of +Munich, published the same conclusion. The reason for restoring the tail +was that the animal had the head constructed in the same way as +Pterodactyles with a long tail, and showed differences from types in +which the tail is short; and there is no known short-tailed +Pterodactyle, with wrist and hand bones, such as characterise this +animal. The side of the face has a general resemblance to the +Pterodactyles from the Lias, for although the framework is firmer, the +four apertures in the head are similarly placed. The nostril is rather +small and elongated, and ascends over the larger antorbital vacuity. The +orbit for the eye is the largest opening in the head, so that these +three apertures successively increase in size, and are followed by the +vertically elongated post-orbital vacuity. The teeth are widely spaced +apart, and those in the skull extend some distance backward to the end +of the maxillary bone. There are few teeth in the lower jaw, and they +correspond to the large anterior teeth of Dimorphodon, there being no +teeth behind the nasal opening. The lower jaw is straight, and the +extremities of the jaws met when the mouth was closed. The breast bone +does not show the keel which is so remarkable in Rhamphorhynchus, which +may be attributed to its under side being exposed, so as to exhibit the +pneumatic foramina. + +The ribs have double heads, more like those of a Crocodile in the region +of the back than is the case with the bird-like ribs from Stonesfield. +The second joint in the wing finger may be longer than the first--a +character which would tend to the association of this Pterodactyle with +species from the Lias; a relation to which attention was first drawn by +Mr. E. T. Newton, who described the Whitby skull. + +The Pterodactyles from the Solenhofen Slate which possess long tails +have a series of characters which show affinity with the other +long-tailed types. The jaws are much more slender. The orbit of the eye +in Rhamphorhynchus is enormously large, and placed vertically above the +articulation for the lower jaw. Immediately in front of the eye are two +small and elongated openings, the hinder of which, known as the +antorbital vacuity, is often slightly smaller than the nostril, which is +placed in the middle length of the head, or a little further back, +giving a long dagger-shaped jaw, which terminates in a toothless spear. +The lower jaw has a corresponding sharp extremity. The teeth are +directed forward in a way that is quite exceptional. Notwithstanding the +massiveness and elongation of the neck vertebrae, which are nearly twice +as long as those of the back, the neck is sometimes only about half the +length of the skull. + +All these long-tailed species from the Lithographic Stone agree in +having the sternum broad, with a long strong keel, extending far +forward. The coracoid bones extend outward like those of a Crocodile, so +as to widen the chest cavity instead of being carried forward as the +bones are in Birds. These bones in this animal were attached to the +anterior extremity of the sternum, so that the keel extended in advance +of the articulation as in other Pterodactyles. The breadth of the +sternum shows that, as in Mammals, the fore part of the body must have +been fully twice the width of the region of the hip-girdle, where the +slenderer hind limbs were attached. The length of the fore limb was +enormous, for although the head suggests an immense length relatively +to the body, nearly equal to neck and back together, the head is not +more than a third of the length of the wing bones. The wing bones are +remarkable for the short powerful humerus with an expanded radial crest, +which is fully equal in width to half the length of the bone. Another +character is the extreme shortness of the metacarpus, usually associated +with immense strength of the wing metacarpal bone. + +The hind limbs are relatively small and relatively short. The femur is +usually shorter than the humerus, and the tibia is much shorter than the +ulna. The bones of the instep, instead of being held together firmly as +in the Lias genera, diverge from each other, widening out, though it +often happens that four of the five metatarsals differ but little in +length. The fifth digit is always shorter. + +The hip-girdle of bones differs chiefly from other types in the way in +which those bones, which have sometimes been likened to the marsupial +bones, are conditioned. They may be a pair of triangular bones which +meet in the middle line, so that there is an outer angle like the arm of +a capital Y. Sometimes these triangular bones are blended into a curved, +bow-shaped arch, which in several specimens appears to extend forward +from near the place of articulation of the femur. This is seen in fossil +skeletons at Heidelberg and Munich. It is possible that this position is +an accident of preservation, and that the prepubic bones are really +attached to the lower border of the pubic bones. + +Immense as the length of the tail appears to be, exceeding the skull and +remainder of the vertebral column, it falls far short of the combined +length of the phalanges of the wing finger. The power of flight was +manifestly greater in Rhamphorhynchus than in other members of the +group, and all the modifications of the skeleton tend towards adaptation +of the animals for flying. The most remarkable modification of structure +at the extremity of the tail was made known by Professor Marsh in a +vertical, leaf-like expansion in this genus, which had not previously +been observed (p. 161). The vertebrae go on steadily diminishing in +length in the usual way, and then the ossified structures which bordered +the tail bones and run parallel with the vertebrae in all the +Rhamphorhynchus family, suddenly diverge downward and upward at right +angles to the vertebrae, forming a vertical crest above and a +corresponding keel below; and between these structures, which are +identified with the neural spines and chevron bones of ordinary +vertebrae, the membrane extends, giving the extremity of the tail a +rudder-like feature, which, from knowledge of the construction of the +tail of a child's kite, may well be thought to have had influence in +directing and steadying the animal's movements. There are many minor +features in the shoulder-girdle, which show that the coracoid, for +example, was becoming unlike that bone in the Lias, though it still +continues to have a bony union with the elongated shoulder-blade of the +back. + + [Illustration: FIG. 56. RESTORATION OF THE SKELETON OF + _RHAMPHORHYNCHUS PHYLLURUS_ + + From the Solenhofen Slate, partly based upon the skeleton + with the wing membranes preserved] + + [Illustration: FIG. 57. RESTORATION OF THE SKELETON OF _SCAPHOGNATHUS + CRASSIROSTRIS_ + + Published in the _Illustrated London News_ in 1875. In which a tail is + shown on the evidence of the structure of the head and hand] + + [Illustration: FIG. 58. SIX RESTORATIONS + + 1. Ramphocephalus. Stonesfield Slate. John Phillips, 1871 + 2. Rhamphorhynchus. O. C. Marsh, 1882 + 3. Rhamphorhynchus. V. Zittel, 1882 + 4. Ornithostoma. Williston, 1897 + 5. Dimorphodon. Buckland, 1836. Tail then unknown + 6. Ornithocheirus. H. G. Seeley, 1865] + +The great German delineator of these animals, Von Meyer, admitted six +different species. Mr. Newton and Mr. Lydekker diminish the number to +four. It is not easy to determine these differences, or to say how far +the differences observed in the bones characterise species or genera. It +is certain that there is one remarkable difference from other and older +Pterodactyles, in that the last or fourth bone in the wing finger is +usually slightly longer than the third bone, which precedes it. There is +a certain variability in the specimens which makes discussion of their +characters difficult, and has led to some forms being regarded as +varieties, while others, of which less material is available, are +classed as species. I am disposed to say that some of the confusion may +have resulted from specimens being wrongly named. Thus, there is a +Rhamphorhynchus called curtimanus, or the form with the short hand. It +is represented by two types. One of these appears to have the humerus +short, the ulna and radius long, and the finger bones long; the other +has the humerus longer, the ulna much shorter, and the finger bones +shorter. They are clearly different species, but the second variety +agrees in almost every detail with a species named hirundinaceus, the +swallow-like Rhamphorhynchus. This identification shows, not that the +latter is a bad species, but that curtimanus is a distinct species which +had sometimes been confounded with the other. While most of these +specimens show a small but steady decrease in the length of the several +wing finger bones, the species called Gemmingi has the first three bones +absolutely equal and shorter than in the species curtimanus, longimanus, +or hirundinaceus. In the same way, on the evidence of facts, I find +myself unable to join in discarding Professor Marsh's species phyllurus, +on account of the different proportions of its limb bones. The humerus, +metacarpus, and third phalange of the wing finger in _Rhamphorhynchus +phyllurus_ are exceptionally short as compared with other species. +Everyone agrees that the species called longicaudus is a distinct one, +so that it is chiefly in slight differences in the proportions of +constituent parts of the skeleton that the types of the Rhamphorhynchus +are distinguished from each other. I cannot quite concur with either +Professor Zittel (Fig. 58, 3) or Professor Marsh (Fig. 58, 2) in the +expansion which they give to the wing membrane in their restorations; +for although Professor Zittel represents the tail as free from the hind +legs, while Professor Marsh connects them together, they both concur in +carrying the wing membrane from the tip of the wing finger down to the +extremity of the ankle joint. I should have preferred to carry it no +further down the body than the lower part of the back, there being no +fossil evidence in favour of this extension so far as specimens have +been described. Neither the membranous wings figured by Zittel nor by +Marsh would warrant so much body membrane as the Rhamphorhynchus has +been credited with. I have based my restoration (p. 161) of the skeleton +chiefly on _Rhamphorhynchus phyllurus._ + + +THE SHORT-TAILED TYPES + +The Pterodactylia are less variable; and the variation among the species +is chiefly confined to relative length of the head, length of the neck, +and the height of the body above the ground. The tail is always so short +as to be inappreciable. Many of the specimens are fragmentary, and the +characters of the group are not easily determined without careful +comparisons and measurements. The bones of the fore limb and wing +finger are less stout than in the Rhamphorhynchus type, while the femur +is generally a little longer than the humerus, and the wing finger is +short in comparison with its condition in Rhamphorhynchus. These +short-tailed Pterodactyles give the impression of being active little +animals, having very much the aspect of birds, upon four legs or two. +The neck is about as long as the lower jaw, the antorbital vacuity in +the head is imperfectly separated from the much larger nasal opening, +the orbit of the eye is large and far back, the teeth are entirely in +front of the nasal aperture, and the post-orbital vacuity is minute and +inconspicuous. The sternum is much wider than long, and no specimens +give evidence of a manubrium. The finger bones progressively decrease in +length. The prepubic bones have a partially expanded fan-like form, and +never show the triradiate shape, and are never anchylosed. About fifteen +different kinds of Pterodactyles have been described from the Solenhofen +Slate, mostly referred to the genus Pterodactylus, which comprises forms +with a large head and long snout. Some have been placed in a genus +(Ornithocephalus, or Ptenodracon) in which the head is relatively short. +The majority of the species are relatively small. The skull in +_Ornithocephalus brevirostris_ is only 1 inch long, and the animal could +not have stood more than 1-1/2 inches to its back standing on all fours, +and but little over 2-1/2 inches standing as a biped, on the hind limbs. + +A restoration of the species called _Pterodactylus scolopaciceps_, +published in 1875 in the _Illustrated London News_ in the position of a +quadruped, shows an animal a little larger, with a body 2-1/2 inches +high and 6 to 7 inches long, with the wing finger 4-1/2 inches long. +Larger animals occur in the same deposit, and in one named +_Pterodactylus grandis_ the leg bones are a foot long; and such an +animal may have been nearly a foot in height to its back, standing as a +quadruped, though most of these animals had the neck flexible and +capable of being raised like the neck of a Goose or a Deer (p. 30), and +bent down like a Duck's when feeding. + + [Illustration: FIG. 59. RESTORATION OF THE SKELETON OF _PTENODRACON + BREVIROSTRIS_ + + From the Solenhofen Slate. The fourth joint of the wing finger appears + to be lost and has not been restored in the figure. (Natural size)] + +The type of the genus Pterodactylus is the form originally described by +Cuvier as_ Pterodactylus longirostris_ (p. 28). It is also known as _P. +antiquus_, that name having been given by a German naturalist after +Cuvier had invented the genus, and before he had named the species. +There are some remarkable features in which Cuvier's animal is distinct +from others which have been referred to the same genus. Thus the head is +4-1/2 inches long, while the entire length of the backbone to the +extremity of the tail is only 6-1/2 inches, and one vertebra in the neck +is at least as long as six in the back, so that the animal has the +greater part of its length in the head and neck, although the neck +includes so few vertebrae. Nearly all the teeth--which are few in number, +short and broad, not exceeding a dozen in either jaw--are limited to the +front part of the beak, and do not extend anywhere near the nasal +vacuity. This is not the case with all. + +In the species named _P. Kochi_, which I have regarded as the type of a +distinct genus, there are large teeth in the front of the jaw +corresponding to those of Pterodactylus, and behind these a smaller +series of teeth extending back under the nostril, which approaches close +to the orbit of the eye, without any indication of a separate antorbital +vacuity. On those characters the genus Diopecephalus was defined. It is +closely allied to Pterodactylus; both agree in having the ilium +prolonged forward more than twice as far as it is carried backward, the +anterior process covering about half a dozen vertebrae, as in +_Pterodactylus longirostris_. A great many different types have been +referred to _Pterodactylus Kochi_, and it is probable that they may +eventually be distinguished from each other. The species in which the +upper borders of the orbits approximate could be separated from those in +which the frontal interspace is wider. + + [Illustration: FIG. 60. CYCNORHAMPHUS SUEVICUS FROM THE SOLENHOFEN + SLATE SHOWING THE SCATTERED POSITION OF THE BONES + + _Original in the Museum at Tuebingen_] + + [Illustration: FIG. 61. CYCNORHAMPHUS SUEVICUS + RESTORATION SHOWING THE FORM OF THE BODY AND THE WING MEMBRANES] + +It is a remarkable feature in these animals that the middle bones of the +foot, termed instep bones or metatarsals, are usually close together, so +that the toes diverge from a narrow breadth, as in _P. longirostris_, +_P. Kochi_, and other forms; but there also appear to be splay-footed +groups of Pterodactyles like the species which have been named _P. +elegans_ and _P. micronyx_, in which the metatarsus widens out so that +the bones of the toes do not diverge, and that condition characterises +the Ptenodracon (_Pterodactylus brevirostris_), to which genus these +species may possibly be referred. Nearly all who have studied these +animals regard the singularly short-nosed species _P. brevirostris_ as +forming a separate genus. For that genus Soemmerring's descriptive name +Ornithocephalus, which he used for Pterodactyles generally, might +perhaps have been retained. But the name Ptenodracon, suggested by Mr. +Lydekker, has been used for these types. + + [Illustration: FIG. 62. _CYCNORHAMPHUS SUEVICUS_ + + Skeleton restored from the bones in Fig. 60] + + [Illustration: FIG. 63. RESTORATION OF SKELETON CYCNORHAMPHUS FRAASI + SHOWING THE LIMBS ON THE RIGHT SIDE + + _From a specimen in the Museum at Stuttgart_] + + [Illustration: FIG. 64. CYCNORHAMPHUS FRAASI + RESTORATION OF THE FORM OF THE BODY] + +Some of the largest specimens preserved at Stuttgart and Tuebingen have +been named _Pterodactylus suevicus_ and _P. Fraasii_. They do not +approach the species _P. grandis_ in size, so far as can be judged from +the fragmentary remains figured by Von Meyer; for what appears to be the +third phalange of the wing finger is 7-1/2 inches long, while in these +species it is less than half that length, indicating an enormous +development of wing, relatively to the length of the hind limb, which +would probably refer the species to another genus. _Pterodactylus +suevicus_ differs from the typical Pterodactyles in having a rounded, +flattened under surface to the lower jaw, instead of the common +condition of a sharp keel in the region of the symphysis. The beak also +seems flattened and swan-like, and the teeth are limited to the front of +the jaw. There appear to be some indications of small nostrils, which +look upward like the nostrils of Rhamphorhynchus, but this may be a +deceptive appearance, and the nostrils are large lateral vacuities, +which are in the position of antorbital vacuities, so that there would +appear to be only two vacuities in the side of the head in these +animals. The distinctive character of the skeleton in this genus is +found in the extraordinary length of the metacarpus and in the complete +ossification of the smaller metacarpal bones throughout their length. +The metacarpal bones are much longer than the bones of the fore-arm, and +about twice the length of the humerus. The first wing phalange is much +longer than the others, which successively and rapidly diminish in +length, so that the third is half the length of the first. There are +differences in the pelvis; for the anterior process of the ilium is very +short, in comparison with its length in the genus Pterodactylus. And the +long stalk of the prepubic bone with its great hammer-headed expansion +transversely in front gives those bones a character unlike other genera, +so that Cycnorhamphus ranks as a good genus, easily distinguished from +Cuvier's type, in which the four bones of the wing are more equal in +length, and the last is more than half the length of the first; while +the metacarpus in that genus is only a little longer than the humerus, +and much shorter than the ulna. The _Pterodactylus suevicus_ has the +neck vertebrae flat on the under side, and relatively short as compared +with the more slender and narrower vertebrae of _P. Fraasii_. + + + + +CHAPTER XV + +ORNITHOSAURS FROM THE UPPER SECONDARY ROCKS + + +When staying at Swanage, in Dorsetshire, many years ago, I had the rare +good fortune to obtain from the Purbeck Beds the jaw of a Pterodactyle, +which had much in common in plan with the _Cycnorhamphus Fraasii_ from +the Lithographic Slate, which is preserved at Stuttgart. The +tooth-bearing part of this lower jaw is 8 inches long as preserved, +extending back 3 inches beyond the symphysis portion in which the two +sides are blended together. It is different from Professor Fraas's +specimen in having the teeth carried much further back, and in the +animal being nearly twice as large. This fragment of the jaw is little +more than 1 foot long, which is probably less than half its original +length. A vertebra nearly 5 inches long, which is more than twice the +length of the longest neck bones in the Stuttgart fossil, is the only +indication of the vertebral column. Professor Owen described a wing +finger bone from these Purbeck Beds, which is nearly 1 foot long. He +terms it the second of the finger. It may be the third, and on the +hypothesis that the animal had the proportions of the Solenhofen fossil +just referred to, the first wing finger bone of the English Purbeck +Pterodactyle would have exceeded 2 feet in length, and would give a +length for the wing finger of about 5 feet 3 inches. For this animal the +name Doratorhynchus was suggested, but at present I am unable to +distinguish it satisfactorily from Cycnorhamphus, which it resembles in +the forms both of the neck bones and of the jaw. Very small +Pterodactyles are also found in the English Purbeck strata, but the +remains are few, and scattered, like these larger bones. + + [Illustration: FIG. 65. THE LONGEST KNOWN NECK VERTEBRA + + From the Purbeck Beds of Swanage. (Half natural size)] + + +ORNITHODESMUS LATIDENS + + [Illustration: FIG. 66. CERVICAL VERTEBRA OF ORNITHODESMUS + + From the Wealden Beds of the Isle of Wight] + +The Wealden strata being shallow, fresh-water deposits might have been +expected to supply better knowledge of Pterodactyles than has hitherto +been available. Jaws of Ornithocheirus sagittirostris have been found +in the beds at Hastings, and in other parts of Sussex. Some fragments +are as large as anything known. The best-preserved remains have come +from the Isle of Wight, and were rewards to the enthusiastic search of +the Rev. W. Fox, of Brixton. In the principal specimen the teeth were +short and wide, the head large and deep with large vacuities, but the +small brain case of that skull is bird-like. The neck bones are 2-1/2 +inches long. In the upper part of the back the bones are united together +by anchylosis, so that they form a structure in the back like a sacrum, +which does not give attachment to the scapula, as in some Pterodactyles +from the Chalk, but the bones are simply blended, as in the +frigate-bird, allied to Pelicans and Cormorants. And then after a few +free vertebrae in the lower part of the back, succeeds the long sacrum, +formed in the usual way, of many vertebrae. I described a sacrum of this +type from the Wealden Beds, under the name _Ornithodesmus_, referable to +another species, which in many respects was so like the sacrum of a Bird +that I could not at the time separate it from the bird type. This genus +has a sternum with a strong deep keel, and the articulation for the +coracoid bones placed at the back of the keel in the usual way, but with +a relation to each other seen in no genus hitherto known, for the +articular surfaces are wedge-shaped instead of being ovate; and instead +of being side by side, they obliquely overlap, practically as in wading +birds like the Heron. I have never seen any Pterodactyle teeth so +flattened and shaped like the end of a lancet; and from this character +the form was known between Mr. Fox and his friends as "latidens." The +name Ornithodesmus is as descriptive of the sternum as of the vertebral +column. The wing bones, as far as they are preserved, have the +relatively great strength in the fore limb which is found in many of the +Pterodactyles of the Cretaceous period, and are quite as large as the +largest from the Cambridge Greensand. In the Sussex species named _P. +sagittirostris_ the lower jaw articulation was inches wide. + + + [Illustration: FIG. 67. STERNUM OF _ORNITHODESMUS_ + + Showing the overlapping facets for the coracoid bones (shaded) behind + the median keel] + + [Illustration: FIG. 68. FRONT OF THE KEEL OF THE STERNUM OF + _ORNITHODESMUS LATIDENS_ + + Showing also the articulation for the coracoid bone] + +A few Pterodactyles' bones have been discovered in the Neocomian sands +of England and Germany, and other larger bones occur in the Gault of +Folkestone and the north of France; but never in such association as to +throw light on the aspect of the skeleton. + + +ORNITHOCHEIRUS + +Within my own memory Pterodactyle remains were equally rare from the +Cambridge Greensand. The late Professor Owen in one of his public +lectures produced the first few fragments received from Cambridge, and +with a knowledge which in its scientific method seemed to border on the +power of creation, produced again the missing parts, so that the bones +told their story, which the work of waves and mineral changes in the +rock had partly obliterated. Subsequently good fortune gave me the +opportunity during ten years to help my University in the acquisition +and arrangement of the finest collection of remains of these animals in +Europe. Out of an area of a few acres, during a year or two, came the +thousand bones of Ornithosaurs, mostly associated sets of remains, each +a part of a separate skeleton, described in my published catalogues, as +well as the best of those at York and in the British Museum and other +collections in London. + +The deposit which yields them, named Cambridge Greensand, may or may not +represent a long period of time in its single foot of thickness; but the +abundance of fossils, obtained whenever the workmen were adequately +remunerated for preserving them, would suggest that the Pterodactyles +might have lived like sea-birds or in colonies like the Penguins, if it +were not that the number of examples of each species found is always +small, and the many variations of structure suggested rather that the +individuals represent the life of many lands. The collections of remains +are mostly from villages in the immediate vicinity of Cambridge, such as +Chesterton, Huntingdon Road, Coldham Common, Haslingfield, Barton, +Shillington, Ditton, Granchester, Harston, Barrington, stretching south +to Ashwell in Bedfordshire on the one hand, as well as further north by +Horningsea into the fens. Each appears to be the associated bones of a +single individual. The remains mostly belong to comparatively large +animals. Some were small, though none have been found so diminutive as +the smallest from the Solenhofen Slate. The largest specimens with long +jaws appear to have had the head measuring not more than eighteen inches +in length, which is less than half the size of the great toothless +Pterodactyles from Kansas. + + [Illustration: FIG. 69. RESTORATION OF THE SKULL OF ORNITHOCHEIRUS + + The parts left white are in the Geological Museum at Cambridge. The + shaded parts have not been found. The two holes are the eye and the + nostril (From the Cambridge Greensand)] + +The Cambridge specimens manifestly belong to at least three genera. +Something may be said of the characters of the large animals which are +included in the genus Ornithocheirus. These fossils have many points of +structure in common with the great American toothless forms which are of +similar geological age. The skull is remarkable for having the back of +the head prolonged in a compressed median crest, which rose above the +brain case, and extended upward and over the neck vertebrae, so as to +indicate a muscular power not otherwise shown in the group. For about +three inches behind the brain this wedge of bone rested on the vertebrae, +and probably overlapped the first three neural arches in the neck. + +Another feature of some interest is the expansion of the bone which +comes below the eye. In Birds this malar or cheek bone is a slender rod, +but in these Pterodactyles it is a vertical plate, which is blended with +the bone named the quadrate bone, which makes the articulation with the +lower jaw in all oviparous animals. + +The beak varies greatly in length and in form, though it is never quite +so pointed as in the American genus, for there is always a little +truncation in front, when teeth are seen projecting forward from a +position somewhat above the palate; the snout is often massive and +sometimes club-shaped. Except for these variations of shape in the +compressed snout, which is characterised by a ridge in the middle of the +palate, and a corresponding groove in the lower jaw, and the teeth, +there is little to distinguish what is known of the skull in its largest +English Greensand fossils from the skull remains which abound in the +Chalk of Kansas. + +This English genus Ornithocheirus, represented by a great number of +species, had the neural arch of the neck bones expanded transversely +over the body of the vertebra in a way that characterises many birds +with powerful necks, and is seen in a few Pterodactyles from Solenhofen. + +It is difficult to resist the conclusion that the neck vertebrae were +not usually more than twice to three times as long as those of the back, +and it would appear that the caudal vertebrae in the English Cretaceous +types were comparatively large, and about twice as long as the dorsal +vertebrae. Unless there has been a singular succession of accidents in +the association of these vertebrae with the other remains, Ornithocheirus +had a tail of moderate length, formed of a few vertebrae as long as those +of the neck, though more slender, quite unlike the tail in either the +long-tailed or short-tailed groups of Solenhofen Pterodactyles, and +longer than in the toothless Pterodactyles of America. + + [Illustration: FIG. 70. CERVICAL VERTEBRA, ORNITHOCHEIRUS + + Under side, half natural size. (Cambridge Greensand)] + +The singular articulation for the humerus at the truncated extremity of +the coracoid bone is a character of this group, as is the articulation +of the scapulae with the neural arches of the dorsal vertebrae, at right +angles to them (p. 115), instead of running over the ribs as in Birds +and as in other Pterodactyles. + +The smaller Pterodactyles have their jaws less compressed from side to +side. The upper arm bone, the humerus, instead of being truncated at its +lower end as in Ornithocheirus, is divided into two or three rounded +articular surfaces. That for the radius, the bone which carries the +wrist, is a distinct and oblique rounded facet, while the ulna has a +rounded and pulley-like articulation on which the hand may rotate. These +differences are probably associated with an absence of the remarkable +mode of union of the scapulae with the dorsal vertebrae. But I have +hesitated to give different names to these smaller genera because no +example of scapula has come under my notice which is not truncated at +the free end. I do not think this European type can be the Nyctodactylus +of Professor Marsh, in which sutures appear to be persistent between the +bodies of the vertebrae and their arches, because no examples have been +found at Cambridge with the neural arches separated, although the +scapula is frequently separated from the coracoid in large animals. + + [Illustration: FIG. 71. UPPER AND LOWER JAWS OF AN ENGLISH + PTERODACTYLE FROM THE CHALK, AS PRESERVED] + + +ORNITHOSTOMA + + [Illustration: FIG. 72. THE PALATE OF THE ENGLISH TOOTHLESS + PTERODACTYLE, ORNITHOSTOMA] + + [Illustration: FIG. 73. TYPES OF THE AMERICAN TOOTHLESS PTERODACTYLE, + ORNITHOSTOMA + + Named by Marsh, Pteranodon] + +The most interesting of all the English Pterodactyle remains is the +small fragment of jaw figured by Sir Richard Owen in 1859, which is a +little more than two inches long and an inch wide, distinguished by a +concave palate with smooth rounded margins to the jaws and a rounded +ridge to the beak. It is the only satisfactory fragment of the animal +which has been figured, and indicates a genus of toothless +Pterodactyles, for which the name Ornithostoma was first used in 1871. +After some years Professor Marsh found toothless Pterodactyles in +Kansas, and indicated several species. There are remains to the number +of six hundred specimens of these American animals in the Yale Museum +alone; but very little was known of them till Professor Williston, of +Lawrence, in Kansas, described the specimens from the Kansas University +Museum, when it became evident that the bones of the skeleton are mostly +formed on the same plan as those of the Cambridge Greensand genus, +Ornithocheirus. They are not quite identical. Professor Williston adopts +for them the name Ornithostoma, in preference to Pteranodon which Marsh +had suggested. Both animals have the dagger-shaped form of jaw, with +corresponding height and breadth of the palate. The same flattened sides +to the snout, converging upwards to a rounded ridge, the same compressed +rounded margin to the jaw, which represents the border in which teeth +are usually implanted, and in both the palate has the same smooth +character forming a single wide concave channel. Years previously I had +the pleasure of showing to Professor Marsh the remarkable characters of +the jaw, shoulder-girdle bones, and scapulae in the Greensand +Pterodactyles while the American fossils were still undiscovered. I +subsequently made the restoration of the shoulder-girdle (p. 115). +Professor Williston states to me that the shoulder-girdle bones in +American examples of Ornithostoma have a close resemblance to those of +Ornithocheirus figured in 1891, as is evident from remains now shown in +the British Museum. It appears that the Kansas bones are almost +invariably crushed flat, so that their articular ends are distorted. The +neck vertebrae are relatively stout as in Ornithocheirus. The hip-girdle +of the American Ornithostoma can be closely paralleled in some English +specimens of Ornithocheirus, though each prepubic bone is triangular in +the American fossils as in _P. rhamphastinus_. They are united into a +transverse bar as in Rhamphorhynchus, unknown in the English fossils. +The femur has the same shape as in Ornithocheirus; and the long tibia +terminates in a pulley. There is no fibula. The sternum in both has a +manubrium, or thick keel mass, prolonged in front of its articular +facets for the coracoid bones, which are well separated from each other. +Four ribs articulate with its straight sides. The animal has four toes +and the fifth is rudimentary; there are no claws to the first and +second. + + [Illustration: FIG. 74. RESTORATION OF THE SKELETON OF _ORNITHOSTOMA + INGENS_ (MARSH) + + From the Niobrara Cretaceous of Western Kansas. Made by Professor + Williston. The original has a spread of wing of about 19 feet 4 + inches. Fragments of larger individuals are preserved at Munich] + +In the restoration which Professor Williston has made the wing +metacarpal is long, and in the shortest specimen measures 1 foot 7 +inches, and in the longest 1 foot 8 inches. This is exactly equal to the +length of the first phalange of the wing finger. The second wing finger +bone is 3 inches shorter, the third is little more than half the length +of the first, while the fourth is only 6-3/4 inches long, showing a +rapid shortening of the bones, a condition which may have characterised +all the Cretaceous Pterodactyles. The short humerus, about 1 foot long, +and the fore-arm, which is scarcely longer, are also characteristic +proportions of Ornithostoma or Pteranodon, as known from the American +specimens. Professor Williston gives no details of the remarkable tail, +beyond saying that the tail is small and short, and that the vertebrae +are flat at the ends, without transverse processes. In the restoration +the tail is shorter than in the short-tailed species from the +Lithographic Slate, and unlike the tail in Ornithocheirus. + + +This is the succession of Pterodactyles in geological time. Their +history is like that of the human race. In the most ancient nations +man's life comes upon us already fully organised. The Pterodactyles +begin, so far as isolated bones are concerned, in the Rhaetic strata; +perhaps in the Muschelkalk or middle division of the Trias. And from the +beginning of the Secondary time they live on with but little diversity +in important and characteristic structures, and so far as habit goes, +the great Pterodactyles of the Upper Chalk of England cannot be said to +be more highly organised than the earlier stiff-tailed genera of the +Lias or the Oolites. There is nothing like evolution. No modification +such as that which derives the one-toed horse or the two-toed ox from +ancestors with a larger number of digits. On the other hand, there is +little, if any, evidence of degeneration. The later Pterodactyles do not +appear to have lost much, although the tail in some of the Solenhofen +genera may be degenerate when compared with the long tail of +Dimorphodon; but the short-tailed types are found side by side with the +long-tailed Rhamphorhynchus. The absence of teeth may be regarded as +degeneration, for they have presumably become lost, in the same way that +Birds now existing have lost the teeth which characterised the fossil +birds--Ichthyornis of the American Greensand, and Archaeopteryx of the +Upper Oolites of Bavaria. But just as some of the earlier Pterodactyles +have no teeth at the extremity of the jaw, such as Dorygnathus and +Rhamphorhynchus, so the loss of teeth may have extended backward till +the jaws became toothless. The specimens hitherto known give no evidence +of such a change being in progress. But just as the division of Mammals +termed Edentata usually wants only the teeth which characterise the +front of the jaw, yet others, like the Great Ant-eater of South America +named Myrmecophaga, have the jaws as free from teeth as the toothless +Pterodactyles or living Birds, and show that in that order the teeth +have no value in separating these animals into subordinate groups any +more than they have among the Monotremata, where one type has teeth and +the other is toothless. + +The following table gives a summary of the Geological History and +succession in the Secondary Rocks of the principal genera of Flying +Reptiles. + + -----------------------+---------------------------------------------- + | NAMES OF THE GENERA. + GEOLOGICAL FORMATIONS. +-----------------------+---------------------- + | British and European. | North American. + -----------------------+-----------------------+---------------------- + Upper Chalk | |} Ornithostoma + | |} (_Pteranodon_) + Lower Chalk |} Ornithocheirus |} Nyctodactylus + Upper Greensand |} | Ornithostoma | + Gault | | | + -----------------------+ | | + Lower Greensand | | | + Wealden | Ornithodesmus | + Purbeck | Doratorhynchus | + -----------------------+ | + Portland |{ Pterodactylus | + |{ Ptenodracon | + Kimeridge Clay and |{ Cycnorhamphus | + Solenhofen Slate |{ Diopecephalus | + |{ Rhamphorhynchus | + Coralline Oolite |{ Scaphognathus | + | | + Oxford Clay | | + -----------------------+ | + Great Oolite and | | + Stonesfield Slate | Rhamphocephalus | + | | + Inferior Oolite | | + -----------------------+ | + Upper Lias |{ Campylognathus | + |{ Dorygnathus | + Lower Lias | Dimorphodon | + -----------------------+ | + Rhaetic | bones | + | | + Muschelkalk | ? bones | + -----------------------+-----------------------+---------------------- + + + + +CHAPTER XVI + +CLASSIFICATION OF THE ORNITHOSAURIA + + +When an attempt is made to determine the place in nature of an extinct +group of animals and the relation to each other of the different types +included within its limits, so as to express those facts in a +classification, attention is directed in the first place to characters +which are constant, and persist through the whole of its constituent +genera. We endeavour to find the structural parts of the skeleton which +are not affected by variation in the dentition, or the proportions of +the extremities, or length of the tail, which may define families or +genera, or species. + +It has already been shown that while in many ways the Ornithosaurian +animals are like Birds, they have also important resemblances to +Reptiles. They are often named Pterosauria. The wing finger gives a +distinctive character which is found in neither one class of existing +animals nor the other, and is common to all the Pterodactyles at present +known. They have been named Ornithosauria as a distinct minor division +of back-boned animals, which may be regarded as neither Reptiles nor +Birds in the sense in which those terms are used to define a Lizard or +Ostrich among animals which still exist. It is not so much that they +mark a transition from Reptile to Bird, as that they are a group which +is parallel to Birds, and more manifestly holds an intermediate place +than Birds do between Reptiles and Mammals. In plan of structure Bird +and Reptile have more in common than was at one time suspected. The late +Professor Huxley went so far as to generalise on those coincidences in +parts of the skeleton, and united Birds and Reptiles into one group, +which he named Sauropsida, to express the coincidences of structure +between the Lizard and the Bird tribes. The idea is of more value than +the term in which it is expressed, because Reptiles are not, as we have +seen, a group of animals which can be defined by any set of characters +as comprehensive as those which express the distinctive features of +Birds. From the anatomist's point of view Birds are a smaller group, and +while some Reptiles have affinity with them, it is rather the extinct +than the living groups which indicate that relation. Other Reptiles have +affinities of a more marked kind with Mammals, and there are points in +the Ornithosaurian skeleton which are distinctly Mammalian. So that when +the Monotreme Mammals are united with South African reptiles known as +Theriodontia, which resemble them, in a group termed Theropsida to +express their mammalian resemblances, it is evident that there is no one +continuous chain of life or gradation in complexity of structure of +animals. + +We have to determine whether the Ornithosauria incline towards the +Sauropsidan or Bird-Reptile alliance, or to the Mammal-Reptile or +Theropsidan alliance. There can be no doubt that the predominant +tendency is to the former, with a minor affinity towards the latter. + +The Ornithosauria are one of a series of groups of animals, living and +extinct, which have been combined in an alliance named the +Ornithomorpha. That group includes at least five great divisions of +animals, which circle about birds, known as Ornithosauria, Crocodilia, +Saurischia, Aves, Ornithischia, and Aristosuchia. Their relations to +each other are not evident in an enumeration, but may be shown in some +degree in a diagram (see p. 190). + + +THE ORNITHOMORPHA + +The Ornithomorpha arranged in this way show that the three middle +groups--carnivorous Saurischia, Aristosuchia, herbivorous +Ornithischia--which are usually united as Dinosauria, intervene between +Birds and Ornithosaurs; and that the Crocodilia and Ornithosauria are +parallel groups which are connected with Birds, by the group of +Dinosaurs, which resembles Birds most closely. + +The Ornithomorpha is only one of a series of large natural groups of +animals into which living and extinct terrestrial vertebrata may be +arranged. And the succeeding diagram may contribute to make evident the +relations of Ornithosauria to the other terrestrial vertebrata (see p. +191). + +Herein it is seen that while the Ornithomorpha approach towards Mammalia +through the Ornithosauria, and less distinctly through the Crocodilia, +they approach more directly to the Sauromorpha, through the Plesiosaurs +and Hatteria; while that group also approaches more directly to the +Mammals through the Plesiosaurs and Anomodonts. + + [Illustration: DIAGRAM OF THE AFFINITIES OF THE ORDERS OF ANIMALS + COMPRISED IN THE ORNITHOMORPHA. + + After a diagram in the _Philosophical Transactions of the Royal + Society_, 1892.] + +The Aristosuchia is imperfectly known, and therefore to some extent a +provisional group. It is a small group of animals. + + [Illustration: DIAGRAM SHOWING THE RELATIONS OF THE ORNITHOMORPHA + TO THE CHIEF LARGE GROUPS OF TERRESTRIAL VERTEBRATA, AND THEIR + AFFINITIES WITH EACH OTHER. + + After a diagram in the _Philosophical Transactions of the Royal + Society_, 1892.] + +Cordylomorpha are Ichthyosaurs and the Labyrinthodont group. +Herpetomorpha include Lacertilia, Homoeosauria, Dolichosauria, +Chameleonoidea, Ophidia, Pythonomorpha. + +The Sauromorpha comprises the groups of extinct and living Reptiles +named Chelonia, Rhynchocephala, Sauropterygia, Anomodontia, Nothosauria, +and Protorosauria. These details may help to explain the place which has +been given to the Ornithosauria in the classification of animals. + + [Illustration: FIG. 75. COMPARISON OF SIX GENERA + + The skulls are seen on the left side in the order of the names below + them] + +Turning to the Pterodactyles themselves, Von Meyer divided them +naturally into short-tailed and long-tailed. The short-tailed indicated +by the name Pterodactylus he further divided into long-nosed and +short-nosed. The short-nosed genus has since been named Ptenodracon +(Fig. 59, p. 167). The long-tailed group was divided into two types--the +Rhamphorhynchus of the Solenhofen Slate (Fig. 56, p. 161) and the +English form now known as Dimorphodon (Fig. 52, p. 150), which had been +described from the Lias. + +The Cretaceous Pterodactyles form a distinct family. So that, believing +the tail to have been short in that group (Fig. 58), there are two +long-tailed as well as two short-tailed families, which were defined +from their typical genera Pterodactylus, Ornithocheirus, +Rhamphorhynchus, and Dimorphodon. + +The differences in structure which these animals present are, first: the +big-headed forms from the Lias like Dimorphodon, agree with the +Rhamphorhynchus type from Solenhofen in having a vacuity in the skull +defined by bone, placed between the orbit of the eye and the nostril. +With those characters are correlated the comparatively short bones which +correspond to the back of the hand termed metacarpals, and the tail is +long, and stiffened down its length with ossified tendons. These +characters separate Ornithosaurs with long tails from those with short +tails. + +The short-tailed types represented by Pterodactylus and Ornithocheirus +have no distinct antorbital vacuity in the skull defined by bone. The +metacarpal bones of the middle hand are exceptionally elongated, and the +tail, which was flexible in both, appears to have been short. These +differences in the skeleton warrant a primary division of flying +reptiles into two principal groups. + +The short-tailed group, which was recognised by De Blainville as +intermediate between Birds and Reptiles, may take the name +Pterodactylia, which he suggested as a convenient, distinctive name. It +may probably be inconvenient to enlarge its significance to comprise not +only the true Pterodactyles originally defined as Pterosauria, but the +newer Ornithostoma and Ornithocheirus which have been grouped as +Ornithocheiroidea. + +The second order, in which the wing membrane appears to have had a much +greater extent, in being carried down the hind limbs, where the +outermost digit and metatarsal are modified for its support, has been +named Pterodermata, to include the types which are arranged around +Rhamphorhynchus and Dimorphodon. + +Both these principal groups admit of subdivision by many characters in +the skeleton, the most remarkable of which is afforded by the pair of +bones carried in front of the pubes, and termed prepubic bones. In the +Pterodactyle family the bones in front of the pubes are always separate +from each other, always directed forward, and have a peculiar fan-shaped +form with concave sides like the bone which holds a similar position in +a Crocodile. In the Ornithocheirus family the prepubic bones appear to +have been originally triangular, but were afterwards united so as to +form a strong continuous bar which extends transversely across the +abdomen in advance of the pubic bones. This at least is the distinctive +character in the genus Ornithostoma according to Professor Williston, +which in many ways closely resembles Ornithocheirus. + +The two families in the long-tailed order named Pterodermata are +separated from each other by a similar difference in their prepubic +bones. In Dimorphodon those bones are separate from each other, and +remain distinct through life, meeting in the middle line of the body in +a wide plate. On the other hand, in Rhamphorhynchus the prepubic bones, +which are at first triangular and always slender, become blended +together into a slight transverse bar, which only differs from that +attributed to Ornithostoma in its more slender bow-shaped form. + + [Illustration: FIG. 76. LEFT SIDE OF PELVIS OF ORNITHOSTOMA + (After Williston)] + +Thus if other characters of the skeleton are ignored and a +classification based upon the structure of the pelvis and prepubic +bones, there would be some ground for associating the long-tailed +Rhamphorhynchus from the Upper Oolites which is losing the teeth in the +front of its jaw with the Cretaceous Ornithostoma, which has the teeth +completely wanting; while the long-tailed Dimorphodon would come into +closer association with the short-tailed Pterodactylus. The drum-stick +bone or tibia in Dimorphodon, with its slender fibula, like that of a +Bird, also resembles a Bird in the rounded and pulley-shaped terminal +end which makes the joint corresponding to the middle of the ankle bones +in man. The same condition of a terminal pulley joint is found in the +Cretaceous Pterodactyles. But in the true Pterodactyles and in +Rhamphorhynchus there usually is no pulley-shaped termination to the +lower end of the drum-stick, for the tarsal bones remain separate from +each other, and form two rows of ossifications, showing the same +differences as separate Dinosaurs into the divisions which have been +referred to, from their Bird-like pelvis and tibio-tarsus, as +Ornithischia in the one case, and Saurischia in the other from their +bones being more like those of living Lizards. + + + + +CHAPTER XVII + +FAMILY RELATIONS OF PTERODACTYLES TO ANIMALS WHICH LIVED WITH THEM + + +Enough has been said of the general structure of Pterodactyles and the +chief forms which they assumed while the Secondary rocks were +accumulating, to convey a clear idea of their relations to the types of +vertebrate animals which still survive on the earth. We may be unable to +explain the reasons for their existence, and for their departure from +the plan of organisation of Reptiles and Birds. But the evidence has not +been exhausted which may elucidate their existence. Sometimes, in +problems of this kind, which involve comparison of the details of the +skeleton in different animals, it is convenient to imagine the +possibility of changes and transitions which are not yet supported by +the discovery of fossil remains. If, for example, the Pterodactyle be +conceived of as divested of the wing finger, which is its most +distinctive character, or that finger is supposed to be replaced by an +ordinary digit, like the three-clawed digits of the hand which we have +regarded as applied to the ground, where, it may be asked, would the +animal type be found which approximates most closely to a Pterodactyle +which had been thus modified? There are two possible replies to such a +question, suggested by the form of the foot. For the old Bird +Archaeopteryx has three such clawed digits, but no wing finger. And some +Dinosaurs also have the hand with three digits terminating in claws, +which are quite comparable to the clawed digits of Pterodactyles. + +The truth expressed in the saying that no man by taking thought can add +a cubit to his stature is of universal application in the animal world, +in relation to the result upon the skeleton of the exercise of a +function by the individual. Yet such is the relation in proportions of +the different parts of the animal to the work which it performs, so +marked is the evidence that growth has extended in direct relation to +use of organs and active life, and that structures have become dwarfed +from overwork, or have wasted away from disuse--seen throughout all +vertebrate animals, that we may fairly attribute to the wing finger some +correlated influence upon the proportions of the animal, as a +consequence of the dependence of the entire economy upon each of its +parts. Therefore if an allied animal did not possess a wing finger, and +did not fly, it might not have developed the lightness of bone, or the +length of limb which Pterodactyles possess. + +The mere expansion of the parachute membrane seen in so-called flying +animals, both Mammals and Reptiles, which are devoid of wings, is +absolutely without effect in modifying the skeleton. But when in the Bat +a wing structure is met with which may be compared to a gigantic +extension of the web foot of the so-called Flying Frog, the bones of the +fingers and the back of the hand elongate and extend under the stimulus +of the function of flight in the same way as the legs elongate in the +more active hoofed animals, with the function of running. Therefore it +is not improbable that the limbs shared to some extent in growth under +stimulus of exercise which developed the wing finger. And if an animal +can be found among fossils so far allied as to indicate a possible +representative of the race from which these Flying Dragons arose, it +might be expected to be at least shorter legged, and possibly more +distinctly Reptilian in the bones of the shoulder-girdle which support +the muscles used in flight. It may readily be understood that the kinds +of life which were most nearly allied to Pterodactyles are likely to +have existed upon the earth with them, and that flight was only one of +the modes of progression which became developed in relation to their +conditions of existence. The principal assemblage of terrestrial animals +available for such comparison is the Dinosauria. They may differ from +Pterodactyles as widely as the Insectivora among Mammals differ from +Bats, but not in a more marked way. Comparisons will show that there are +resemblances between the two extinct groups which appeal to both reason +and imagination. + +Dinosaurs are conveniently divided by characters of the pelvis first +into the order Saurischia, which includes the carnivorous Megalosaurus +and the Cetiosaurus, with the pelvis on the Reptile plan; and secondly +the order Ornithischia, represented by Iguanodon, with the pelvis on the +Bird plan. It may be only a coincidence, but nevertheless an interesting +one, that the characters of those two great groups of reptiles, which +also extend throughout the Secondary rocks, are to some extent +paralleled in parts of the skeleton of the two divisions of +Pterodactyles. This may be illustrated by reference to the skull, +pelvis, hind limb, and the pneumatic condition of the bones. + + [Illustration: FIG. 77. COMPARISON OF THE SKULL OF THE DINOSAUR + ANCHISAURUS WITH THE ORNITHOSAUR DIMORPHODON] + +The Saurischian Dinosauria have an antorbital vacuity in the side of the +skull between the nasal opening and the eye, as in the long-tailed +Ornithosaurs named Pterodermata. In some of the older genera of these +carnivorous Dinosaurs of the Trias, the lateral vacuities of the head +are as large as in Dimorphodon. But in some at least of the Iguanodont, +or Ornithischian Dinosaurs, there is no antorbital vacuity, and the side +of the face in that respect resembles the short-tailed Pterodactylia. +The skull of a carnivorous Dinosaur possesses teeth which, though easily +distinguished from those of Pterodactyles, can be best compared with +them. The most striking difference is in the fact that in the Dinosaur +the nostrils are nearly terminal, while in the Pterodactyle they are +removed some distance backward. This result is brought about by growth +taking place, in the one case at the front margin of the maxillary bone +so as to carry the nostril forward, and in the other case at the back +margin of the premaxillary bone. Thus an elongated part of the jaw is +extended in front of the nostril. Hence there is a different proportion +between the premaxillary and maxillary bones in the two groups of +animals, which corresponds to the presence of a beak in a bird, and its +absence in living reptiles. It is not known whether the extremity of the +Pterodactyle's beak is a single bone, the intermaxillary bone, such as +forms the corresponding toothless part of the jaw in the South African +reptile Dicynodon, or whether it is made by the pair of bones called +premaxillaries which form the extremity of the jaw in most Dinosaurs. +Too much importance may perhaps be attached to such differences which +are partly hypothetical, because the extinct Ichthyosaurus, which has an +exceptionally long snout, has the two premaxillary bones elongated so as +to extend backward to the nostrils. A similar elongation of those bones +is seen in Porpoises, which also have a long snout; and the bones are +carried back from the front of the head to the nostrils, which are +sometimes known as blowholes. But the Porpoise has those premaxillary +bones not so much in advance of the bones which carry teeth named +maxillary, as placed in the interspace between them. The nostrils, +however, are not limited to the extremity of the head in all Dinosaurs. +If this region of the beak in Dimorphodon be compared with the +corresponding part of a Dinosaur from the Permian rocks, or Trias, the +relation of the nostril to the bones forming the beak may be better +understood. + + [Illustration: FIG. 78. COMPARISON OF THE SKULL OF THE DINOSAUR + ORNITHOSUCHUS WITH THE ORNITHOSAUR DIMORPHODON] + +In the sandstone of Elgin, usually named Trias, a small Dinosaur is +found, which has been named Ornithosuchus, from the resemblance of its +head to that of a Bird. Seen from above, the head has a remarkable +resemblance to the condition in Rhamphorhynchus, in the sharp-pointed +beak and positions of the orbits and other openings. In side view the +orbits have the triangular form seen in Dimorphodon, and the preorbital +vacuities are large, as in that genus, while the lateral nostrils, which +are smaller, are further forward in the Dinosaur. The differences from +Dimorphodon are in the articulation for the jaw being carried a little +backward, instead of being vertical as in the Pterodactyle, and the bone +in front of the nose is smaller. Notwithstanding probable differences +in the palate, the approximation, which extends to the Crocodile-like +vacuity in the lower jaw, is such that by slight modification in the +skull the differences would be substantially obliterated by which the +skull of such an Ornithosaur is technically distinguished from such a +Dinosaur. + +The back of the skull is clearly seen in the Whitby Pterodactyle, and +its structure is similar to the corresponding part of such Dinosaurs as +Anchisaurus or Atlantosaurus, without the resemblance quite amounting to +identity, but still far closer than is the resemblance between the same +region in the heads of Crocodiles, Lizards, Serpents, Chelonians. Few of +these fossil Dinosaur skulls are available for comparison, and those +differ among themselves. The coincidences rather suggest a close +collateral relation than prove the elaboration of one type from the +other. They may have had a common ancestor. + +The Trias rocks near Stuttgart have yielded Dinosaurs as unlike +Pterodactyles as could be imagined, resembling heavily armoured +Crocodiles, in such types as the genus Belodon. Its jaws are compressed +from side to side, as in many Pterodactyles, and the nostrils are at +least as far backward as in Rhamphorhynchus. Belodon has preorbital +vacuities and postorbital vacuities, but the orbit of the eye is never +large, as in Pterodactyles. It might not be worth while dwelling on such +points in the skull if it were not that the pelvis in Belodon is a basin +formed by the blending of the expanded plates of the ischium and the +pubis, into a sheet of bone which more nearly resembles the same region +in Pterodactyles than does the ischio-pubic region in other Dinosaurian +animals like Cetiosaurus. + +The backbone in a few Dinosaurs is suggestive of Pterodactyles. In such +genera as have been named Coelurus and Calamospondylus, in which the +skeleton is only partially known, the neck vertebrae become elongated, so +as to compare with the long-necked Pterodactyles. The cervical rib is +often very similar to that type, and blended with the vertebra, as in +Pterodactyles and Birds. The early dorsal vertebrae of Pterodactyles +might almost be mistaken for those of Dinosaurs. The tail vertebrae of a +Pterodactyle are usually longer than in long-tailed Dinosauria. + +In the limbs and the bony girdles which support them there is more +resemblance between Pterodactyles and Dinosaurs than might have been +anticipated, considering their manifest differences in habit. Thus all +Dinosaurs have the hip bone named ilium prolonged in front of the +articulation for the femur as well as behind it, almost exactly as in +Pterodactyles and Birds (see p. 95). There is some difference in the +pubis and ischium which is more conspicuous in form than in direction of +the bones. There is a Pterodactyle imperfectly preserved, named +_Pterodactylus dubius_, in which the ischium is directed backward and +the pubis downward, and the bones unite below the acetabular cavity for +the head of the femur to work in, but do not appear to be otherwise +connected. In Rhamphorhynchus the connexion between these two thickened +bars is made by a thin plate of bone. In such a Dinosaur as the American +carnivorous Ceratosaurus the two bars of the pubis and ischium remain +separate and diverging, and there is no film of bone extending over the +interspace between them. The development of such a bony condition would +make a close approximation between the Ornithosaurian pelvis and that +of those Dinosaurs which closely resemble Pterodactyles in skull and +teeth. + + [Illustration: FIG. 79. LEFT SIDE OF PELVIS + A Pterodactyle is shown between a carnivorous Dinosaur above and a + herbivorous Dinosaur below] + +Another pelvic character of some interest is the blending of the pubis +and ischium of the right and left sides in the middle line of the body. +There are some genera of Dinosaurs like the English Aristosuchus from +the Weald, and the American genera Coelurus, Ceratosaurus, and others, +in which the pubic bones, instead of uniting at their extremities, are +pinched together from side to side, and unite down the lower part of +their length, terminating in an expanded end like a shoe, which is seen +to be a separate ossification, and probably formed by a pair of +ossifications joined in the median line. This small bone, which is below +the pubes, and in these animals becomes blended with them, we may regard +as a pair of prepubic bones like those of Pterodactyles and Crocodiles, +except that they have lost the stalk-like portions, which in those +animals are developed to compensate for the diminished length of the +pubic bones. The prepubic bones may also be developed in Iguanodon, in +which a pair of bones of similar form remains throughout life in advance +of the pubes, as in Pterodactyles. In those Dinosauria with the +Bird-like type of pelvis the pubic bone is exceptionally developed, +sending one process backward and another process forward, so that there +is a great gap between these diverging limbs to the bone. In the region +behind the sternum to which the ribs were attached, and in front of the +pelvis, is a pair of bones in Iguanodon shaped like the prepubic bones +of Dimorphodon. They have sometimes been interpreted as a hinder part of +the sternum, but may more probably be regarded as a pair of prepubic +bones articulating each with the anterior process of the pubis (see Fig. +80). The small bones found at the extremities of the pubes in such +carnivorous Dinosaurs as Aristosuchus are blended by bony union with the +pubes. The bones in Iguanodon are placed behind the sternal region +without any attachment for sternal ribs, and the expanded processes +converge forwards from the stalk and unite exactly like the prepubic +bones of Ornithosaurs. While this character, on the one hand, may link +Pterodactyles with the Dinosaurs, on the other hand it may be a link +between both those groups and the Crocodiles, in which the front pair of +bones of the pelvis has also appeared to be representative of the +prepubic bones of Flying Reptiles (see Fig. 32, p. 98). + + [Illustration: FIG. 80. DIAGRAM OF THE PELVIS SEEN FROM BELOW IN AN + ORNITHOSAUR AND A DINOSAUR] + +The resemblances between Pterodactyles and Dinosaurs in the hind limb +are not of less interest, though it is rather in the older Pterodactyles +such as Dimorphodon, Pterodactylus, and Rhamphorhynchus that the +resemblance is closest with the slender carnivorous Dinosaurs. They +never have the head of the thigh bone, femur, separated from its shaft +by a constricted neck, as in the Pterodactyles from the Chalk. In many +ways the thigh bone of Dinosaurs tends towards being Avian; while that +of Pterodactyles inclines towards being Mammalian, but with a tendency +to be Bird-like in the older types, and to be Mammal-like in the most +recent representatives of the group in the Chalk. + +The bones of the leg in Ornithosaurs, known as tibia and fibula, are +remarkable for the circumstance first that they resemble Birds in the +fibula being slender and only developed in its upper part towards the +femur, and secondly that in a genus like Dimorphodon this drum-stick +bone has the two upper bones of the ankle blended with the tibia, so as +to form a rounded pulley joint which is indistinguishable from that of a +Bird (see p. 102). There is a large number of Dinosaurs in which this +remarkable distinctive character of Birds is also found. Only, Dinosaurs +like Iguanodon, for instance, have the slender fibula as long as the +tibia, and contributing to unite with the separate ankle bones of the +similarly rounded pulley at the lower end. There are no Birds in which +the tarsal bones remain separated and distinct throughout life. But in +Pterodactylus from Solenhofen, as in a number of Dinosaurs, especially +the carnivorous genera, the bones of the tarsus remain distinct +throughout life, and never acquired such forms as would have enabled the +ankle bone, termed astragalus, to embrace the extremity of the tibia, as +it does in Iguanodon. Thus the resemblance of the Ornithosaur drum-stick +is almost as close to Dinosaurs as to Birds. + +There is great similarity between Dinosaurs and Pterodactyles seen in +the region of the instep, known as the metatarsus. These bones are +usually four in number, parallel to each other, and similar in form. +They are commonly longer than in Dinosaurs; but among some of the +carnivorous Dinosaurs their length approximates to that seen in +Pterodactyles. In neither group are the bones blended together by bony +union, while they are always united in Birds, as in Oxen and similar +even-hoofed mammals. Dinosaurs agree with Pterodactyles in maintaining +the metatarsal bones separate, but they differ from them and agree with +Birds frequently, in having the number of metatarsal bones reduced to +three, as in Iguanodon, though Dinosaurs often have as many as five +digits developed. + +The toe bones, the phalanges of these digits of the hind limb, are +usually longer in Pterodactyles than in Dinosaurs, but they resemble +carnivorous Dinosaurs in the forms of their sharp terminal bones for the +claws, which are similarly compressed from side to side. + +So diverse are the functions of the fore limb in Dinosaurs and +Pterodactyles, and so remarkably does the length of the metacarpal +region of the back of the hand vary in the long-tailed and short-tailed +Ornithosaurs, that there is necessarily a less close correspondence in +that region of the skeleton between these two groups of animals; for the +Pterodactyle fore limb is modified in relation to a function which can +only be paralleled among Birds and Bats; and yet neither of those groups +of animals approximates closely in this region of the skeleton to the +Flying Reptile. Under all the modifications of structure which may be +attributed to differences of function, some resemblance to Dinosaurs may +be detected, which is best evident in the upper arm bone, humerus; is +slight in the fore-arm bones, ulna and radius; and becomes lost towards +the extremity of the limb. + +If the tendency of the thigh bone to resemble a Mammalian type of femur +(p. 100) is a fundamental, deep-seated character of the skeleton, it +might be anticipated that a trace of Mammalian character would also be +found in the humerus. For what the character is worth, the head of the +humerus does show a closer approximation to a Monotreme Mammal than is +seen in Birds, and is to some extent paralleled in those South African +reptiles which approximate to Mammals most closely. Not the least +remarkable of the many astonishing resemblances of these light aerial +creatures to the more heavy bodied Dinosaurs is the circumstance that +the humerus in both groups makes a not dissimilar approach to that of +certain Mammals. + +These illustrations may be accepted as demonstrating a relationship +between the Ornithosaurs and Dinosaurs now compared, which can only be +explained as results of influence of a common parentage upon the forms +of the bones. But more interesting than resemblances of that kind is the +similarity that may be traced in the way in which air is introduced into +cavities in the bones in both groups. In some of the imperfectly known +Dinosaurs, like Aristosuchus, Coelurus, and Thecospondylus, the bone +texture is as thin as in Pterodactyles, and the vertebrae are excavated +by pneumatic cavities, which are amazing in size when compared with the +corresponding structures in birds, for the vertebra is often hollowed +out so that nothing remains but a thin external film like paper for its +thickness. In the Dinosaurian genus Coelurus this condition is as well +marked in the tail and back as it is in the neck. The essential +difference from Birds appears to be that in the larger carnivorous +Dinosaurs the pneumatic condition of the bones is confined to the +vertebral column; while Birds and Pterodactyles have the pneumatic +condition more conspicuously developed in the limb bones. The pneumatic +skeleton, however, appears to be absent from the herbivorous types like +Iguanodon and all Dinosaurs which have the Bird-like form of pelvis, and +are most Bird-like in the forms of bones of the hind limb. It is +possible that some of the carnivorous Dinosaurs also possessed limb +bones with pneumatic cavities. Many of those bones are hollow with very +thin walls. If their cavities were connected with the lungs the foramina +are inconspicuous and unlike the immense holes seen in the sides of the +vertebrae. + +According to the late Professor Marsh, the limbs of Coelurus and its +allies, which at present are imperfectly known, are in some cases +pneumatic. Therefore there is a closer fundamental resemblance between +some carnivorous Dinosaurs and Pterodactyles than might have been +anticipated. But the skull of Coelurus is unknown, and the fragments of +the skeleton hitherto published are insufficient to do more than show +that the two types were near in kindred, though distinct in habit. Each +has elaborated a skeleton which owes much to the common stock which +transmitted the vital organs, and the tendency of the bones to take +special forms; but which also owes more than can be accurately measured +to the action of muscles in shaping the bones and the influence of the +mechanical conditions of daily life upon the growth of the bones in both +of these orders of animals. Enough is known to prove that all Dinosaurs +cannot be regarded as Ornithosaurs which have not acquired the power of +flight; though the evidence would lead us to believe that the primitive +Ornithosaur was a four-footed animal, before the wing finger became +developed in the fore limb as a means of extending a patagial membrane, +like the membrane which in the hind limb of Dimorphodon has bent the +outermost digit of the foot upward and outward to support the +corresponding organ of flight extending down the hind legs. + +It may thus be seen that the characters of Ornithosaurs which have +already been spoken of as Reptilian, as distinguished from the +resemblances to Birds, may now with more accuracy be regarded as +Dinosaurian. The Dinosaurs, like Pterodactyles, must be regarded as +intermediate in some respects between Reptiles and Birds. The +resemblances enumerated would alone constitute a partial transition from +the Reptile to the Bird, although no Dinosaurs have organs of flight; +many are heavily armoured with plates of bone, and few, if any, +approximate in the technical parts of the skeleton to the Bird class, +except in the hind limbs. Yet Dinosaurs have sometimes been regarded as +standing to Birds in the relation of ancestors, or as parallel to an +ancestral stock. + +Before an attempt can be made to estimate the mutual relation of the +Flying Reptiles to Dinosaurs on the one hand, and to Birds on the other, +it may be well to remember that the resemblance of such a Dinosaur as +Iguanodon to a Bird in its pelvis and hind limb is not more remarkable +than that of Pterodactyles to Birds in the shoulder-girdle and bones of +the fore limb. The keeled sternum, the long, slender coracoid bones and +scapulae, are absolutely Bird-like in most Ornithosaurs; and that region +of the skeleton only differs from Birds in the absence of a furculum +which represents the clavicles, and is commonly named the +"merry-thought." The elongated bones of the fore-arm and the hand, +terminating in three sharp claws, are characters in which the fossil +bird Archaeopteryx resembles the Pterodactyle Rhamphorhynchus, a +resemblance which extends to a similar elongation of the tail. It is +remarkable that the resemblance should be so close, since Archaeopteryx +affords the only bird's skeleton known to be contemporary which can be +compared with the Solenhofen Flying Reptiles. The resemblance may +possibly be closer than has been imagined. The back of the head of +Archaeopteryx is imperfectly preserved in the region of the quadrate +bone, malar arch, and temporal vacuity. And till these are better known +it cannot be affirmed that the back of the head is more Reptilian in +Pterodactyles than in the oldest Birds. The side of the head in +Archaeopteryx is distinguished by the nostril being far forward, the +vacuity in front of the orbit being as large as in the Pterodactyle +Scaphognathus from Solenhofen and other long-tailed Pterodactyles. + + + + +CHAPTER XVIII + +HOW PTERODACTYLES MAY HAVE ORIGINATED + + +Ornithosauria have many characters inseparably blended together which +are otherwise distinctive of Reptiles, Birds, and Mammals, and +associated with peculiar structures which are absent from all other +animals. They are not quite alone in this incongruous combination of +different types of animals in the same skeleton. Dinosaurs, which were +contemporary with Ornithosaurs, approximate to them in blending +characters of Birds with the structure of a Reptile and something of a +Mammal in one animal. If an Ornithosaur is Reptilian in its backbone, in +the articular ends of each vertebra having the cup in front and ball +behind in the manner of Crocodiles, Serpents, and many Lizards, a +Dinosaur like Iguanodon, which had the reversed condition of ball in +front and cup behind in its early vertebrae, may be more Mammalian than +Avian in a corresponding resemblance of the bones to the neck in hoofed +Mammals. But while Pterodactyles are sometimes Mammalian in having the +head of the thigh bone moulded as in carnivorous Mammals and Man, the +corresponding bone in a Dinosaur is more like that of a Bird. And while +the Pterodactyle shoulder-girdle is often absolutely Bird-like, that +region in Dinosaurs can only be paralleled among Reptiles. + +Such combinations of diverse characters are not limited to animals which +are extinct. There were not wanting scientific men who regarded the +Platypus of Australia, when first sent to Europe, as an ingenious +example of Eastern skill, in which an animal had been compounded +artificially by blending the beak of a Bird with the body of a Mammal. +Fuller knowledge of that remarkable animal has continuously intensified +wonder at its combination of Mammal, Bird, and Reptile in a single +animal. It has broken down the theoretical divisions between the higher +Vertebrata, demonstrating that a Mammal may lay eggs like a Reptile or +Bird, that the skull may include the reptilian characters of the malar +arch and pre-frontal and post-frontal bones, otherwise unknown in +Mammals and Birds. The groups of Mammals, Birds, and Reptiles now +surviving on the earth prove to be less sharply defined from each other +when the living and extinct types are considered together. But in +Pterodactyles, Mammal Bird and Reptile lose their identity, as three +colours would do when unequally mixed together. + +This mingling of characteristics of different animals is not to be +attributed to interbreeding, but is the converse of the combination of +characters found in hybrid animals. It is no exaggeration to say that +there is a sense in which Mammal, Bird, Reptile, and the distinctive +structures of the Ornithosaur, have simultaneously developed from one +egg, in the body of one animal. + +The differences between those vertebrate types of animals consist +chiefly in the way in which their organisation is modified, by one +strain of characters being eliminated so that another becomes +predominant, while a distinctive set of structures is elaborated in each +class of animals. The earlier geological history of the higher +Vertebrata is very imperfectly known, but the evidence tends to the +inference that the older representatives of the several classes +approximate to each other more closely than do their surviving +representatives, so that in still earlier ages of time the distinction +between them had not become recognisable. The relation of the great +groups of animals to each other, among Vertebrata, is essentially a +parallel relation, like the colours of the solar spectrum, or the +parallel digits of the hand. It was natural, when only the surviving +life on the earth was known, to imagine that animals were connected in a +continuous chain by successive descent, but Mammals have given no +evidence of approximation to Birds; and Birds discover no evidence that +their ancestors were Reptiles, in the sense in which that word is used +to define animals which now exist on the earth. When the variation which +animals attain in their maturity and exhibit in development from the egg +was first realised, it was imagined that Nature, by slow summing up and +accumulation of differences which were observed, would so modify one +animal type that it would pass into another. There is little evidence to +support belief that the changes between the types of life have been +wrought in that way. The history of fossil animals has not shown +transitions of this kind from the lower to higher Vertebrata, but only +intermediate, parallel groups of animals, analogous to those which +survive, and distinct from them in the same way as surviving groups are +distinct from each other. The circumstance that Mammals, Birds, and +Reptiles are all known low down in the Secondary epoch of geological +time, is favourable to the idea of their history being parallel rather +than successive. Such a conception is supported by the theory of +elimination of characters from groups of animals as the basis of their +differentiation. This loss appears always to be accompanied by a +corresponding gain of characters, which is more remarkable in the soft, +vital organs than in the skeleton. The gain in higher Vertebrates in the +bones is chiefly in the perfection of joints at their extremities; but +the gain in brain, lungs, heart, and other soft parts is an elaboration +of those structures and an increase in amount of tissue. + +The resemblances of Ornithosaurs to Mammals are the least conspicuous of +their characters. Those seen in the upper arm bone and thigh bone are +manifestly not derived from Mammals. They cannot be explained as +adaptations of the bones to conditions of existence, because there is no +community of habit to be inferred between Pterodactyles and Mammals, in +which the bones are in any way comparable. + +Other fossil animals show that a fundamentally Reptilian structure is +capable of developing in the Mammalian direction in the skull, backbone, +shoulder-girdle, hip-girdle, and limbs, so as to be uniformly Mammalian +in its tendencies. This is proved by tracing the North American Texas +fossils named Labyrinthodonts, through the South African Theriodonts, +towards the Monotremata and other Mammalia. Just as those animals have +obliterated all traces of the Bird from their skeletons, Birds have +obliterated the distinctive characters of Mammals. The Ornithosaur has +partially obliterated both. With a skull and backbone marked by typical +characters of the Reptile, it combines the shoulder-girdle and +hip-girdle of a Bird, with characters in the limbs which suggest both +those types in combination with Mammals. + +The bones have been compared in the skeleton of each order of existing +Reptiles, and found to show side by side with their peculiar characters +not only resemblances to the other Reptilia, but an appreciable number +of Mammalian and Avian characters in their skeletons. The term +"crocodile," for example, indicates an animal in which the skeleton is +dominated by one set of peculiar characters. Crocodiles retain enough of +the characteristics of several other orders of reptiles to show that an +animal sprung from the old Crocodile stock might diverge widely from +existing Crocodiles by intensifying what might be termed its dormant +characters in the Crocodile skeleton. Comparing animals together bone by +bone it is possible to value the modifications of form which they put +on, and the resemblances between them, so as to separate the inherited +wealth of an animal's affinities with ancestors or collateral groups, +from the peculiar characters which have been acquired as an increase +based upon its typical bony possessions or osteological capital. There +is no part of the Pterodactyle skeleton which is more distinctly +modified than the head of the upper arm bone, which fits into the socket +between the coracoid bone and the shoulder-blade. The head of the +humerus, as the articular part is named, is somewhat crescent-shaped, +convex on its inner border, and a little concave on its outer border, +and therefore unlike the ball-shaped head of the upper arm bone in Man +and the higher Mammals. It is much more nearly paralleled in the little +group of Monotremata allied to the living Ornithorhynchus. In that sense +the head of the humerus in a Pterodactyle has some affinity with the +lowest Mammalia, which approach nearest to Reptiles. The character might +pass unregarded if it were not found in more striking development in +fossil Reptiles from Cape Colony, which from having teeth like Mammals +are named Theriodontia. In several of those South African reptiles the +upper arm bone approaches closer to the humerus in Ornithosaurs than to +Ornithorhynchus. Such coincidences of structure are sometimes dismissed +from consideration and placed beyond investigation by being termed +adaptive modifications; but there can be no hope of finding community of +habit between the burrowing Monotreme, the short-limbed Theriodont, and +the flying Pterodactyle which might have caused this articular part of +the upper arm bone to acquire a form so similar in animals constructed +so differently. If the resemblance in the humerus to Monotremes in this +respect is not to be attributed to burrowing, neither can the crescent +form of its upper articulation be attributed to flight; for in Birds the +head of the bone is compressed, but always convex, and Bats fly without +any approach to the Pterodactyle form in the head of the humerus. This +apparently trivial character may from such comparisons be inferred to be +something which the way of life of the animal does not sufficiently +account for. These deepest-seated parts of the limbs are slow to adapt +themselves to changing circumstances of existence, and retain their +characters with moderate variation of the bones in each of the orders +or classes of animals. It therefore is safer to regard Mammalian +characters, as well as the resemblances which Pterodactyles show to +other kinds of animals, as due to inheritance from a time when there was +a common stock from which none of these animals which have been +considered had been distinctly elaborated. + +A few characters of Ornithosaurs are regarded as having been acquired, +because they are not found in any other animals, or have been developed +only in a portion of the group. The most obvious of these is the +elongated wing finger; but in some genera, like Dimorphodon, there is +also a less elongation of the fifth digit of the foot, and perhaps in +all genera there is a backward development of the first digit of the +hand, which is without a claw, and therefore unlike the clawed digit of +a Bat. An acquired character of another kind, which is limited to the +Cretaceous genera, is seen in the shoulder-blade being directed +transversely outward, so that its truncated end articulates by a true +joint with the early vertebrae of the back, and defended the cavity +inclosed by the ribs by a strong bony external arch. And finally, as the +animals later in time acquire short tails, and relatively longer limbs, +the bones of the back of the hand, termed metacarpals, acquire greater +and distinctive length, which is not seen in the long-tailed types like +Rhamphorhynchus. + +These and such-like acquired characters distinguish the class of animals +from all groups with which it may be compared, and mark the possible +limits of variation of the skeleton within the boundary of the order. +But no further variation of these parts of the skeleton could make a +transition to another order of animals, or explain how the +Pterodactyles came into existence, because the characters which separate +orders and classes of animals from each other differ in kind from those +which separate smaller groups, named genera and species, of which the +order is made up. The accumulation of the characters of genera will not +sum up into the characters of an order or class. + +In making the division of Vertebrate animals into classes the skeleton +is often almost ignored. Its value is entirely empirical and based upon +the observed association of the various forms of bones with the more +important characters of the brain and other vital organs. What is +understood as a Mammalian or Avian character in the skeleton is the form +of bone which is found in association with the soft vital organs which +constitute an animal a Mammal or a Bird. + +The characters which theoretically define a Mammal appear to be the +enormous overgrowth of the cerebral hemispheres of the brain by which +the cerebrum comes into contact with the cerebellum, as among Birds. +This character distinguishes both groups of animals from all Reptiles, +recent and fossil. But in examining the mould of the interior of the +brain case it is rare to have the bones fitting so closely to the brain +as to prove that the lateral expansion below the cerebrum and cerebellum +is formed by the optic lobes of the brain. Otherwise the brain of a +Pterodactyle might be as like to the brain of Ornithorhynchus as it is +like that of a Bird (Fig. 19). But it is precisely in this condition of +arrangement of the parts of the brain that the specimens appear to be +most clear. The lateral mass of brain in specimens of Ornithosaurs from +the Lower Secondary rocks appears to be transversely divided into back +and front parts, which may be thought to correspond to the structures in +a Mammal brain named _corpora quadrigemina_, but to be placed as the +optic lobes are placed in Birds, and to have relatively greater +dimensions than in Mammals. No evidence has been observed of this +transverse division of the optic lobes of the brain in Pterodactyles +from the Chalk and Cretaceous rocks, and so far as the evidence goes +this part of the brain was shaped as in birds, but rather smaller. + +The brain is the only soft organ in which a Mammalian character could be +evidenced. The uniformity in character of the brain throughout the group +in Mammals is remarkable, in reference to the circumstance that the +reproduction varies in type; the lowest, or Monotreme division, being +oviparous. If there is no necessary connexion between the Mammalian +brain and the prevalent condition under which the young are produced +alive, it may be affirmed also that there is no necessary connexion +between the form of the brain and the form of the bones, since the brain +cavity in Theriodont reptiles shows no resemblance to that of a Mammal, +while the bones are in so many respects only paralleled among +Monotremata and Mammalia. The variety of forms which the existing +Mammalian orders of animals assume, shows the astonishing range of +structure of the skeleton which may coexist with the Mammalian brain. +And therefore we are led to the conclusion that any other fundamental +modification of brain--such as distinguishes the class of Birds--might +also be associated with forms and structures of the skeleton which +would vary in similar ways. In other words, if for convenience we define +a Mammal by its form of brain, structure of the heart and lungs, and +provision for nutrition of the young, without regard to the covering of +the skin, which varies between the scales of a pangolin and the +practically naked skin of the whale--a bird might be also defined by its +peculiar conditions of brain and lungs, without reference to the +feathered condition of the skin, though the feathered condition extends +backward in time to the Upper Secondary rocks, as seen in the +Archaeopteryx. + +The Avian characters of Pterodactyles are the predominant parts of their +organisation, for the conditions of the brain and lungs shown by the +moulds of the brain case and the thin hollow bones with conspicuous +pneumatic foramina, give evidence of a community of vital structures +with Birds, which is supported by characters of the skeleton. If any +classificational value can be associated with the distribution of the +pneumatic foramina as tending to establish membership of the same class +for animals fashioned on the same plan of soft organs, the evidence is +not weakened when a community of structures is found to extend among the +bones to such distinctive parts of the skeleton as the sternum, +shoulder-girdle, bones of the fore-arm and fore-leg; for in all these +regions the Pterodactyle bones are practically indistinguishable from +those of Birds. This is the more remarkable because other parts of the +skeleton, such as the humerus and pelvis, show a partial resemblance to +Birds, while the parts which are least Avian, like the neck bones, have +no tendency to vary the number of the vertebrae, in the way which is +common among Birds, following more closely the formula of the seven +cervical vertebrae of Mammals. + +It would therefore appear from the vital community of structures with +Birds, that Pterodactyles and Birds are two parallel groups, which may +be regarded as ancient divergent forks of the same branch of animal +life, which became distinguished from each other by acquiring the +different condition of the skin, and the structures which were developed +in consequence of the bony skeleton ministering to flight in different +ways; and with different habit of terrestrial progression, this extinct +group of animals acquired some modifications of the skeleton which Birds +have not shown. There is nothing to suggest that Pterodactyles are a +branch from Birds, but their relation to Birds is much closer, so far as +the skeleton goes, than is their relation with the flightless Dinosaurs, +with which Birds and Pterodactyles have many characters in common. + +On the theory of elimination of character which I have used to account +for the disappearance of some Mammalian characters from the +Pterodactyle, that loss is seen chiefly in the removal of the parts +which have left a Reptilian articulation of the lower jaw with the +skull, and the articulation of the vertebrae throughout the vertebral +column by a modified cup-and-ball form of joint. The furculum of the +Bird is always absent from the Pterodactyle. No specimen has shown +recognisable clavicles or collar-bones. Judged by the standard of +existing life, Pterodactyles belong to the same group as Birds, on the +evidence of brain and lungs, but they belong to a different group on +account of the dissimilar modifications of the skeleton and apparent +absence of feathers from the skin. + +The most impressive facts in the Pterodactyle skeleton, in view of these +affinities, are the structures which it has in common with Reptiles. +Some structures are fundamental, like the cup-and-ball articulation of +the vertebrae, which is never found in birds or mammals. Although not +quite identical with the condition in any Reptile, this structure is +approximately Lizard-like or Crocodile-like in the cup-and-ball +character. It shows that the deepest-seated part of the skeleton is +Reptile-like, though it may not be more Reptilian than is the vertebral +column of a Mammal, if comparison is made between Mammals and extinct +groups of animals known as Reptiles, such as Dinosaurs and Theriodontia. + +The orders of animals which have been included under the name Reptilia +comprise such different structural conditions of the parts of the +skeleton which may be termed reptilian in Ornithosaurs, that there is +good reason for regarding the cup-and-ball articulation as quite a +distinctive Reptilian specialisation, in the same sense that the +saddle-shaped articulation between the bodies of adjacent vertebrae in a +bird is an Avian specialisation. From the theoretical point of view the +Ornithosaur acquired its Reptilian characters simultaneously with its +Avian and Mammalian characters. + +There is nothing in the structure of the skeleton of the Dinosauria, to +which Ornithosaurs approximate in several parts of the body, which would +help to explain the cup-and-ball articulation of the backbone, if the +Flying Reptile were supposed to be an offshoot from the carnivorous +Dinosaurs. + +The elimination of Reptile characters from so much of the skeleton, and +the substitution for them of the characters of Birds and Mammals, would +be of exceptional interest if there had been any ground for regarding +the flying animal as more nearly related to a Reptile than to a Bird. +But if the evidence from the form of the brain and nature of the +pneumatic organs seen in the limb bones accounts for the Avian features +of the skeleton, the Reptilian condition of the vertebral column helps +to show a capacity for variation, and that the fixity of type and +structure, which the skeleton of the modern Bird has attained, is not +necessarily limited to or associated with the vital organs of Birds. + +The variation of the cup-and-ball articulation in the neck of a +Chelonian, which makes the third vertebra cupped behind, the fourth +bi-convex, the fifth cupped in front, and the sixth flattened behind, +shows that too much importance may be attached to the mode of union of +these bones in Serpents, Crocodiles, and those Lizards which have the +cup in front; for while in Lizards the anterior cup, oblique and +depressed, is found in most of its groups, the Geckos show no trace of +the cup-and-ball structure, and in that respect resemble the Hatteria of +New Zealand. + +If, therefore, the cup-and-ball articulation of vertebrae in +Ornithosauria has any significance as a mark of affinity to Reptiles, it +could only be in approximation to those living Reptiles which possess +the same character, and would have it on the hypothesis that both have +preserved the structure by descent from an earlier type of animal. This +hypothesis is negatived by the fact that the cup-and-ball articulation +is unknown in the older fossil Reptiles. + +Although the articulation for the lower jaw with the skull in +Ornithosaurs is only to be paralleled among Reptiles, the structure is +adapted to a brain case which is practically indistinguishable from that +of a Bird, except for the postorbital arch. + +The hypothesis of descent, therefore, becomes impossible, in any +intelligible form, in explanation of distinctive character of the +skeleton. The hypothesis of elimination may also seem to be +insufficient, unless the potential capacity for new development be +recognised as concurrent, and as capable of modifying each region of the +skeleton, or hard parts of the animal, in the same way that the soft +organs may be modified. From which we infer that all structures, which +distinguish the several grades of organisation in modern +classifications, soft parts and hard parts alike, may come into +existence together, in so far as they are compatible with each other, in +any class or ordinal division of animals. + +Although the young Mammal passes through a stage of growth in which the +brain may be said to be Reptilian, there is no good ground for inferring +that Mammal or Bird type of skeleton was developed later in time than +that of Reptiles. The various types of Fishes have the brains in general +so similar to those of Reptiles that it is more intelligible for all the +vertebrate forms of brain to have differentiated at the same time, under +the law of elimination of characters, than that there should be any +other bond of union between the classes of animals. + +If we ask what started the Ornithosauria into existence, and created the +plan of construction of that animal type, I think science is justified +in boldly affirming that the initial cause can only be sought under the +development of patagial membranes, such as have been seen in various +animals ministering to flight. Such membranes, in an animal which was +potentially a Bird in its vital organs, have owed development to the +absence of quill feathers. Thus the wing membrane may be the cause for +the chief differences of the skeleton by which Ornithosaurs are +separated from Birds, for the stretch of wing in one case is made by the +skin attached to the bones, and in the other case by feathers on the +skin so attached as to necessitate that the wing bones have different +proportions from Ornithosaurs. + +It is a well-known observation that each great epoch of geological time +has had its dominant forms of animal life, which, so far as the earth's +history is known now, came into existence, lived their time, and were +seen no more. In the same way the smaller groups of species and genera +included in an ordinal group of animals or class have abounded, giving a +tone to the life of each geological formation, until the vitality of the +animal is exhausted, and the species becomes extinct or ceases to +preponderate. This process is seen to be still modifying the life on the +earth, when some kinds of animals and plants are introduced to new +conditions. Plants appear to wage successful war more easily than +animals. The introduction of the Cactus in some parts of Cape Colony has +locally modified both the fauna and flora, just as the Anacharis +introduced into England spread from Cambridge over the whole country, +and became for many years the predominant form of plant life in the +streams. The Rabbit in Australia is a historic pest. Something similar +to this physical fertility and increase appears to take place under new +circumstances in certain organs within the bodies of animals, by the +development of structures previously unknown. A familiar example is seen +in the internal anatomy of the Trout introduced into New Zealand, where +the number of pyloric appendages about the stomach has become rapidly +augmented, while the size and the form of the animal have changed. The +rapidity with which some of these changes have been brought about would +appear to show that Nature is capable of transforming animals more +rapidly than might have been inferred from their uniform life under +ordinary circumstances. Growth of the vital organs in this way may +modify the distinctive form of any vital organ, brain or lungs, and thus +as a consequence of modification of the internal structures due to +changes of food and habit, bring a new group of animals into existence. +And just as the group of animals ceases to predominate after a time, so +there comes a limit to the continued internal development of vital +structures as their energy fails, for each organ behaves to some extent +like an independent organism. + +Under such explanations of the mutual relations of the parts of animals, +and groups of animals, time ceases to be a factor of primary importance +in their construction or elaboration. The supposed necessity for +practically unlimited time to produce changes in the vital organs which +separate animals into great orders or classes is a nightmare, born of +hypothesis, and may be profitably dismissed. The geological evidence is +too imperfect for dogmatism on speculative questions; but the nature of +the affinities of Ornithosaurs to other animals has been established on +a basis of comparison which has no need of theory to justify the facts. +It is not improbable that the primary epoch of time, even as known at +present, may be sufficiently long to contain the parent races from which +Ornithosaurs and all their allies have arisen. + +In thus stating the relation of Ornithosaurs to other animals the Flying +Reptile has been traced home to kindred, though not to its actual +parents or birthplace. There is no geological history of the rapid or +gradual development of the wing finger, and although the wing membrane +may be accepted as its cause of existence, the wing finger is powerfully +developed in the oldest known Pterodactyles as in their latest +representatives. + +Pterodactyles show singularly little variation in structure in their +geological history. We chronicle the loss of the tail and loss of teeth. +There is also the loss of the outermost wing digit from the hind foot as +a supporter of the wing membrane. But the other variations are in the +length of the metacarpus, or of the neck, or head. One of the +fundamental laws of life necessitates that when an animal type ceases to +adapt its organisation and modify its structures to suit the altered +circumstances forced upon it by revolutions of the earth's surface its +life's history becomes broken. It must bend or break. + +The final disappearance of these animals from the earth's history in the +Chalk may yet be modified by future discoveries, but the Flying Reptiles +have vanished, in the same way as so many other groups of animals which +were contemporary with them in the Secondary period of time. Such +extinctions have been attributed to catastrophes, like the submergence +of land, so that the habitations of animals became an area gradually +decreasing in size, which at last disappeared. It appears also to be a +law of life, illustrated by many extinct groups of animals, that they +endure for geological ages, and having fought their battle in life's +history, grow old and unable to continue the fight, and then disappear +from the earth, giving place to more vigorous types adapted to live +under new conditions. + +The extinct Pterodactyles hold a relation to Birds in the scheme of life +not unlike that which Monotremata hold to other Mammals. Both are +remarkable for the variety of their affinities and resemblances to +Reptiles. The Ornithosauria have long passed away; the Monotremes are +nearing extinction. Both appear to be supplanted by parallel groups +which were their contemporaries. Birds now fill the earth in a way that +Flying Reptiles never surpassed; but their flight is made in a different +manner, and the wing is extended to support the animal in the air, +chiefly by appendages to the skin. + +If these fossils have taught that Ornithosaurs have a community of soft +vital organs with Dinosaurs and Birds, they have also gone some way +towards proving that causes similar to those which determined the +structural peculiarities of their bony framework, originated the special +forms of respiratory organs and brain which lifted them out of +association with existing Reptiles. + + +These old flying animals sleep through geological ages, not without +honour, for the study of their story has illuminated the mode of origin +of animals which survive them, and in cleaving the rocks to display +their bones we have opened a new page of the book of life. + + + + +APPENDIX + + +The best public collections of Ornithosaurian remains in England are +in the British Museum (Natural History); Museum of Practical Geology, +Royal College of Surgeons; the University Museum, Oxford; Geological +Museum, Cambridge; and the Museum of the Philosophical Society at +York. + +Detailed descriptions and original figures of the principal specimens +mentioned or referred to may be found in the following writings:-- + + H. v. Meyer, _Reptilien aus dem Lithograph_. _Schiefer_. 1859. Folio. + v. Quenstedt, _Pterodactylus suevicus_. 1855. 4to. + Goldfuss, _Nova Acta Leopold_. XV. + v. Munster, _Nova Acta Leopold_. XV. + A. Wagner, _Abhandl. Bayerischen Akad._, vi., viii. + Cuvier, _Annales du Museum_, xiii. 1809. + " _Ossemens fossiles_, v. 1824. + Buckland, _Geol. Trans._, ser. 2, iii. + R. Owen, _Palaeontographical Society_. 1851, 1859, 1860, 1870, 1874. + K. v. Zittel, _Palaeontographica_, xxix. 1882. + T. C. Winkler, _Mus. Teyler Archives_. 1874, 1883. + Oscar Fraas, _Palaeontographica_, xxv. 1878. + Anton Fritsch, _Boehm. Gesell. Sitzber_. 1881. + R. Lydekker, _Catalogue of Fossil Reptilia in British Museum_ I. 1888. + O. C. Marsh, _Amer. Jour. Science_. 1882, 1884. + S. W. Williston, _Kansas University Quarterly_. 1893, 1896. + E. T. Newton, _Phil. Trans. Royal Soc._ 1888, 1894. + H. G. Seeley, _Ornithosauria_. 8vo. 1870. + " _Annals and Mag. Natural Hist._ 1870, 1871, 1890, 1891. + " _Linn. Society_. 1874, 1875. + " _Geol. Mag._ 1881. + Felix Pleininger, _Palaeontographica_. 1894, 1901. + + + + +INDEX + + +A + + Abdominal ribs, 85, 154 + + Accumulation of characters, 220 + + Acetabulum, 95 + + Acquired characters, 219 + + Adjacent land, 136 + + Air cells, 10, 48 + + Albatross, 23, 36, 176 + + Alligator, brain, 53; + pelvis, 98 + + American Greensand, 185 + + -- ornithosaurs, 87, 126 + + Amphibia, 4, 191 + + Anabas, 17 + + Anacharis, 227 + + Anchisaurus, 199 + + Angle of lower jaw, 75 + + Ankle bones, 103, 195, 207 + + Anomodonts, 192 + + Ant-eater of Africa, 142; + India, 40; + South America, 40, 185 + + Apteryx, lungs, 48; + pelvis, 95 + + Aquatic mammals, 141 + + Aramis, scapular arch, 113 + + Archaeopteryx, 58, 76, 104, 130, 197, 211 + + Aristosuchus, 129, 190, 205, 209 + + Armadillo, 40, 141 + + Articulation of the jaw, 12, 75 + + Ashwell, 177 + + Atlantosaurus, 202 + + Atlas and axis, 80, 81 + + Aves, 190 + + Avian characters, 220, 222 + + +B + + Backbone, 78, 84 + + Banz, 148 + + Barbastelle, 25 + + Barrington, 177 + + Barton, 177 + + Bat, 38, 110, 197; + sternum of, 107; + metacarpus, 128 + + Bavaria, 156, 185 + + Beak, horny, 74, 178 + + Bear, skull of, 12; + femur, 100 + + Bel and the Dragon, 15 + + Belodon, 202 + + Bird, 80, 110, 120 + + -- resemblances, 63, 65, 71, 95, 102, 108, 113, 119, 120, 211 + + Bird-reptile, 188 + + Bird wing, 128, 130 + + Birds in flight, 22; + with teeth, 76 + + Black-headed bunting, 47 + + Blainville, D. de, 30, 193 + + Blood, temperature of, 56 + + Bohemia, 34 + + Bonaparte, Prince Charles, 30 + + Bones of birds, variation in, 41 + + -- of reptiles, variation in, 42 + + -- about the brain, 69 + + -- in the back, 84 + + Bone texture, 59, 209 + + Bonn Museum, 32, 85, 156 + + Brain and breathing organs, 55 + + Brain cavity, in birds and reptiles, 52; + in mammals, 221, 226; + in Solenhofen pterodactyles, 54, 220 + + Brazil, 34 + + Breathing organs, 8 + + Bridgewater Treatise, 143 + + British Museum, 133, 183 + + Brixton, Isle of Wight, 55, 174 + + Buckland, Dean, 143, 148, 231 + + Burrowing limb, 38 + + +C + + Cactus, 227 + + Calamospondylus, 203 + + Cambridge Greensand, 33, 89, 176 + + -- Museum, 177 + + Camel, 83 + + Campylognathus, 68, 71, 135; + size of, 149 + + Canary, 47 + + Carnivorous dinosaurs, 129 + + Carpus, 122 + + Caudal fin, 91, 161 + + -- vertebrae, 89, 92, 203 + + Ceratodus, 4, 5, 9, 17 + + Ceratosaurus, 203, 204 + + Cervical rib, 81 + + Cetacea, 40 + + Cetiosaurus, 198, 203 + + Chalinolobus, 25 + + Chalk, pterodactyles in, 136; + of Kansas, 103, 132 + + Chameleon, 17, 51, 70; + scapula, 112; + sternum, 107 + + Chameleonoidea, 191 + + Cheek bones, 178 + + Chelonia, 86, 112, 193 + + Chesterton, 177 + + Chlamydosaurus, 21 + + _Chrysochloris capensis_, 121 + + Classification, 192; + on pelvis characters, 195; + of dinosaurs, 198 + + Clavicles, 111, 112 + + Claw, 105, 116, 183, 208 + + Coelurus, 203, 209 + + Coldham Common, 177 + + Collar bone, 111 + + Collini, 27 + + Comparison with dinosaurs, 198; + of pelvis, 204, 206; + of skulls, 192, 199, 201 + + Cope, Professor, 31, 34 + + Coracoid, 109, 112, 113 + + Cordylomorpha, 191 + + Cormorant, 70, 174; + sternum, 108 + + Corpora quadrigemina, 221 + + Crisp, Dr., on pneumatic skeleton, 47 + + Crocodile, characters of, 217; + heart, 56; + lung, 9; + shoulder-girdle, 111; + skull, 46; + vertebrae, 79 + + Crocodilia, 190 + + Curlew, 68 + + Cuvier, 1, 27, 28, 54, 76, 77, 130, 231 + + Cycnorhamphus, 70, 94, 171, 173, 204 + + _Cycnorhamphus Fraasii_, 80, 96, 169 + + -- _suevicus_, 169, 170 + + Cypselus, 42 + + +D + + _Dacelo gigantea_, 63 + + Darwin, 3 + + Davy, Dr. John, 142 + + Deuterosaurus, 97 + + Dicynodon, 200 + + _Dicynodon lacerticeps_, 71 + + Digits, of ostrich, 23; + of pterodactyle, 128 + + Digits with claws, 130; + foot bones in, 105 + + Dimorphodon, 63, 64, 66, 67, 73, 74, 83, 90, 102, 113, 143, 192, 194, + 199, 201, 206 + + Dinosauria, 6, 77, 84, 87, 95, 129, 144, 198, 209 + + Dinosaurs from Lias, 135, 192; + from Elgin, 201, 207; + Stuttgart, 202; + Trias dinosaurs, 199, 200 + + Diopecephalus, 168 + + Diving birds, 23, 83, 102 + + Dolichosauria, 191 + + Dolphin, 107 + + Doratorhynchus, 173 + + Dorygnathus, 74, 148 + + Dragons, 3, 15, 17 + + Drumstick bone, 103, 195 + + Duck, 22, 83 + + +E + + Echidna, 75, 76, 95, 100 + + Edentata, 185 + + Edentulous beak, 153 + + Eichstaedt, 32 + + Elephant, head of, 46 + + Enumeration of characters, 223, 225 + + Ephesus, winged figure, 16 + + Epiphysis to first phalange, 123 + + Exocoetus, 18 + + Extinctions, 129 + + Eye hole, 144; + sclerotic bones in, 65 + + +F + + Farren, William, 34 + + Femur, 100 + + Fibula, 102, 183, 206 + + Fifth outer digit, 132; + in foot, 145 + + Figure from temple at Ephesus, 16 + + First phalange, 151 + + Fish-eating crocodile, 137 + + Flight, organs of, 17; + in bats, 25 + + Flying limb, 38 + + Flying fishes, 18, 57; + foxes, 26; + frogs, 19, 197; + gecko, 21, 24; + lizards, 20; + reptiles, 37, 46; + squirrel, 24 + + Foot, 104; + digits in, 105, 146 + + Fore leg, 102, 206 + + -- limb, 38, 107, 116, 120 + + Four claws, 147 + + Fox, Rev. W., 55, 174 + + Fraas, Professor Oscar, 172, 231 + + Frigate bird, vertebrae of, 86, 174 + + Frog, lungs of, 8 + + Furculum, 114 + + +G + + Gaudry, Professor A., 31 + + Gavial, 136 + + Gecko, 21, 23 + + Genera, comparison of, 192 + + Geological distribution, 186 + + Gills, 4 + + Giraffe, 38, 39 + + Glossy starling, 47 + + Golden eagle, 120 + + -- mole, 121 + + Goldfuss, 30, 231 + + Granchester, 177 + + Great ant-eater, 40, 185 + + Guillemot, 102 + + Gull, 22 + + +H + + Haarlem, Teyler Museum at, 32 + + Habits, probable, 134, 176, 198 + + Hairless skins, 141 + + Hand in mammals, 38 + + Harston, 177 + + Haslingfield, 177 + + Hastings, 174 + + Hatteria lung, 9, 27; + brain, 53; + skull, 70, 77; + ribs, 86; + a reptile type, 13 + + Head, characters of, 76 + + Heidelberg Museum, 32, 54, 159 + + Herpetomorpha, 191 + + Heron, 65, 174 + + Hesperornis, 76 + + Hind foot, 104, 135 + + -- limb, 93, 99, 159, 206 + + Hip-girdle in whale tribe, 39, 159 + + Homoeosauria, 191 + + Horningsea, 177 + + Horse, metacarpus of, 127; + vertebrae of, 79 + + Humerus, 46, 117, 217 + + Huxley, Professor, 31, 89, 154, 188 + + Hyo-mandibular arch, 13 + + Hypothesis of descent, 226 + + Hyrax, 101 + + +I + + Ichthyornis, 76 + + Ichthyosaurus, 6, 191 + + Iguanodon, 209; + pelvis, 206 + + Ilium, 93, 95, 96, 98, 204 + + Instep, 105, 207 + + Inherited characters, 217 + + Interclavicle, 111 + + Ischium, 93, 96, 203, 204 + + Isle of Wight, 174 + + +J + + Jaw, in birds, 12; + in fishes, 13; + in mammals, 12; + in reptiles, 13; + in pterodactyles, 63; + suspension of, 11, 74, 76 + + -- lower, 75 + + +K + + Kansas, Chalk of, 72, 103, 115; + University Museum of, 181 + + Kelheim, 32 + + Keuper, 33 + + Kimeridge Clay, 132 + + Kingfisher, 63 + + Kiwi, 23 + + +L + + Labyrinthodontia, 191 + + Lachrymal bones, 67 + + Laramie rocks, 34 + + Largest ornithosaur, 133 + + Lateral vacuities in skull, 147 + + Lawrence in Kansas, 181 + + Lengths of bones, 146 + + Lepidosiren, 17 + + Lias, 33 + + Lithographic Slate, 35, 156 + + Lizards, 20, 21, 27, 123 + + Llama, neck of, 79, 83 + + Loach, swim bladder of, 52 + + Lower jaw, 12, 74, 76, 149 + + Lumbar vertebrae, 89 + + Lungs, 47; + in apteryx, 48; + in chameleon, 51; + in ostrich, 49; + in reptiles, 8, 9, 51 + + Lydekker, R., 160, 169, 231 + + Lyme Regis, 33 + + +M + + Macrocercus, palate of, 71 + + Malar bone, 67 + + Mallard, 22 + + Mammal, 8, 12, 24, 79, 53, 95 + + Mammalia, 38, 141 + + Mammalian characters, 12, 220 + + Mammoth, 141 + + Manis, 40, 57, 142 + + Manubrium of sternum, 108, 109, 183 + + Marrow bones in a bird, 134 + + Marsh, Professor O. C., 31, 72, 90, 115, 121, 131, 140, 160, 165, + 180, 181, 210, 231 + + Marsupial, 70, 94, 99 + + Megalosaurus, 129, 198 + + Merganser, 108 + + Merry-thought, 114 + + Metacarpus, 116, 124, 126, 128, 130 + + Metatarsal bones, 104, 207, 208 + + Meyer, Hermann von, 31, 45, 46, 85, 105, 108, 121, 160, 192, 231 + + Moa of New Zealand, 35 + + Mole, humerus, 38; + sternum, 107 + + Monotremes, 70, 94, 111, 121, 185, 218 + + Mososaurus, 77 + + Movement of the leg, 101 + + Mugger, 137 + + Munich Museum, 32, 159 + + Munster, von, 231 + + Muschelkalk, 184 + + Museum, 32, 156, 231, 159; + Natural History, 133, 231 + + Myrmecophaga, 185 + + +N + + Names of genera, 183 + + Natural History Museum, 38, 231 + + Neck, 79; + in Dimorphodon, 145; + in Giraffe, 39; + in Llama, 79; + in Pterodactyles, 80; + in Whales, 39 + + Newton, E. T., 55, 70, 158, 160, 201, 232 + + New Zealand Bat, 25 + + -- -- Hatteria, 68 + + Niobrara rock, 183 + + Nostril, bones round the, 62; + small, 147 + + Notarium, 87, 115 + + Nothosauria, 192 + + Nusplingen, 32 + + Nyctodactylus, 115, 180 + + +O + + Obliteration of characters, 216 + + Opercular bones, 13 + + Ophidia, 52, 191 + + Optic lobes, 53, 221 + + Organs of flight, 17 + + Ornithischia, 190, 198 + + Ornithocephalus, 166 + + Ornithocheirus, atlas and axis, 81; + brain, 55, 69; + carpus, 124; + cervical vertebra, 83, 179; + claw phalange, 129; + coracoid, 109; + femur, 100; + pelvis, 98; + pubic bones, 194; + sternum, 109; + shoulder-girdle, 115; + remains, 176; + teeth, 74, 76; + absence of teeth, 138 + + _Ornithocheirus machaerorhynchus_, 139; + _microdon_, 139 + + Ornithocheiroidea, 193 + + Ornithodesmus, neck bones, 173, 175; + coracoid, 109, 116; + dorsal vertebrae, 86; + remains of _O. latidens_, 173; + _O. sagittirostris_, 175 + + Ornithomorpha, 189 + + Ornithorhynchus, 40, 53, 95, 117 + + Ornithosauria, 30, 31, 50, 52, 58, 72, 89, 95, 104, 108, 125, 132, + 133, 143, 187, 190, 192, 216 + + Ornithostoma, 66, 69, 72, 180; + lower jaw, 75, 76; + pelvis, 98; + sternum, 110; + phalange, 122; + size, 133; + skull, 181, 182 + + Ornithosuchus, 201 + + Orycteropus, 96 + + _Ossa innominata_, 93 + + Ossified ligaments, 150 + + Ostrich, 23, 45, 49, 113, 129 + + Owen, Sir R., 31, 36, 46, 48, 110, 117, 143, 172, 176, 180, 231 + + Owl, 46, 53 + + Oxford Clay, 33, 156 + + -- University Museum, 154 + + Ox, vertebra of, 79; + metacarpus, 127 + + +P + + Palate, bones of, 71 + + Pangolin, 142 + + Pappenheim, 32 + + Parallel groups, 215 + + Parrot, 71 + + Patagial membranes, 227 + + Pelican, 174 + + Pelvis, 88, 94-98, 151, 195, 202, 204, 206 + + Penguin, 41, 42, 104, 176 + + Periophthalmus, 17 + + Peterborough, bones from, 113, 156 + + Phalanges, 129, 132; + wing finger, 155 + + Phillips, Professor John, 155 + + Pigeon, 119 + + Platydactylus, 21 + + Platypus, 214 + + Plesiosaurus, 6, 73, 75, 93, 189 + + Pleininger, 149, 232 + + Pneumatic foramina, 45, 83, 88, 132, 209 + + Pond, Mr., 34 + + Porcupine, 40 + + Porpoise, 38, 73, 141, 200 + + Premaxillary bones, 77, 200, 205 + + Prepubic bones, 94, 96-98, 194, 204, 205 + + Protorosauria, 192 + + _Ptenodracon brevirostris_, 64, 99, 167, 169, 192 + + Pterodactyle aspects, 35; + avian characters, 222; + beak, 200; + brain, 53; + coracoid, 113; + discovery, 27, 33; + foot, 104; + fore limb, 117; + history in Germany, 31, 148; + hand, 130; + hind limb, 100; + long tails, 156; + palate, 71; + sacrum, 89; + short tails, 165; + size, 35, 133; + sacrum, 89; + skull, 192; + teeth, 73; + vertebrae, 80 + + Pterodactyles from Kansas Chalk, 177, 181 + + -- from Lias Clay, 135, 147, 152 + + -- from Neocomian Sand, 176 + + -- from Oxford Clay, 155 + + -- from Purbeck beds, 173 + + -- from Solenhofen Slate, 156, 158 + + -- from Stonesfield Slate, 153, 158 + + Pterodactylia, 30, 165, 193, 199 + + _Pterodactylus antiquus_, 167; + _brevirostris_, 99, 167, 169; + _crassirostris_, 156; + _dubius_, 87, 96, 97, 203; + _elegans_, 169; + _Fraasii_, 169; + _grandipelvis_, 87, 90; + _grandis_, 102, 167, 169; + _Kochi_, 12, 61, 87, 90, 168, 169; + _longirostris_, 28, 90, 96, 101, 103, 105, 167, 169; + _micronyx_, 105, 169; + _rhamphastinus_, 183; + _scolopaciceps_, 105, 166; + _spectabilis_, 83; + _suevicus_, 169 + + Pterodermata, 194, 199 + + Pteroid bone of first digit, 121 + + Pteromys, 24 + + Pterosauria, 187, 193 + + Pterygoid bones, 72, 147 + + Pythonomorpha, 191 + + +Q + + Quadrate bone, 12, 68, 77 + + Quenstedt, 231 + + +R + + Rabbit, 227 + + Radius, 119, 120 + + Redshanks, 22 + + Relation between head and tail, 157, 193 + + Reptile, 6, 79, 80 + + Resin, 136 + + Restorations-- + Campylognathus, palate of, 71 + Dimorphodon, 143, 147, 164 + Ornithocheirus, 164 + Ornithostoma, 164, 183 + Ptenodracon, 167 + Pterodactylus, 29, 30 + Rhamphocephalus, 164 + Rhamphorhynchus, 161, 164 + Scaphognathus, 163 + + Rhacophorus, 19 + + Rhaetic beds, 184 + + Rhamphocephalus, 113, 136, 153 + + Rhamphorhynchus, 118, 192; + foot, 104; + hind limb, 99; + pelvis, 95; + sacrum, 88; + skull, 54, 63-6, 69; + sternum, 108; + tail, 91; + teeth, 73; + tibia and fibula, 103; + web-footed, 105 + + _Rhamphorhynchus curtimanus_, 163; + _hirundinaceus_, 163; + _longimanus_, 164; + _phyllurus_, 91, 165 + + Rhinoceros, 40, 141 + + Rhopoladon, 97 + + Rhynchocephala, 192 + + Roc, 36 + + Rochester, 136 + + Running limb, 38 + + Ryle, Bishop, 17 + + +S + + Sacrum, 87, 88 + + St. George, 15 + + St. Ives, 156 + + Sarcorhamphus, 102 + + Saurians, 27 + + Saurischia, 190, 195, 198, 199 + + Sauromorpha, 191, 192 + + Sauropsida, 188 + + Sauropterygia, 192 + + Scaphognathus, 64, 85, 140, 152, 192, 212 + + _Scaphognathus crassirostris_, 73-5, 83 + + Scapular arch, 111, 113 + + Scelidosaurus, 135 + + Sclerotic circle, 65 + + Seals, 41 + + Sedgwick, Professor Adam, v, 46 + + Shillington, 77 + + Shoebill, 67 + + Shoe-shaped prepubic bones, 204, 205 + + Short-tailed pterodactyles, 165, 193 + + Shoulder-girdle, 107, 111, 114, 115, 183 + + Siberia, 141 + + Simultaneous origin of characters, 214, 224 + + Skin covering, 40, 41, 58, 139, 140 + + Skulls, 68 + + Sloth, 112 + + Snipe, 47, 68 + + Solenhofen Slate, 28, 32, 88, 153, 156 + + Soemmerring, 29 + + South African reptiles, 188, 208, 216 + + Spotted fly-catcher, 47 + + Squamosal bone, 12, 13 + + Sternal ribs, 110 + + Sternum, 107, 158 + + Stonesfield Slate, 33, 88, 153 + + Structures common to reptiles, 224 + + Stuttgart Museum, 32, 172, 203 + + Swanage, 172 + + Swan, neck of, 80, 113 + + Swift, 50 + + Swimming limb, 38 + + Synotus, 25 + + Syrinx, 48 + + +T + + Tail, description of, 90; + in Cretaceous Pterodactyles, 193 + -- long, 156; + short, 166; + in Dimorphodon, 145; + in Ornithocheirus, 179 + + Tanystrophoeus, long vertebrae in, 79 + + Tarsal bones, 102, 207 + + Tarso-metatarsus, 128 + + Teeth, 73, 137, 138; + in porpoise, 40 + + Temperature of blood, 56 + + Temporal arches, 68 + + -- bone, 12 + + -- fossa, 67 + + Teredo, 137 + + Texas fossils, 216 + + Thecospondylus, 209 + + Theriodont pelvis, 97 + + -- reptiles, 75; + of Russia, 96, 97; + of South Africa, 96, 117 + + Theropsida, 188 + + Thigh bone, 100, 206, 211 + + Three claws, 146, 197 + + Tibia, 102, 195; + in Iguanodon, 207 + + Toothless mammals, 40 + + -- pterodactyles, 138, 181; + beak of pterodactyles, 150 + + Transition from reptiles to birds, 211 + + Tree frogs, 21 + + Trias dinosaurs, 199 + + Triceratops, pelvis of, 204 + + Trout, 139; + of New Zealand, 228 + + Tuatera, 13 + + Tuebingen Museum, 32 + + Tundras, 141 + + Tunny, 57 + + Turtles, neck bones, 79 + + +U + + Ulna, description of, 119 + + Uncinate process of ribs, 85 + + Unlimited time, 228 + + Upper arm bone, 117 + + -- Greensand, remains in, 136 + + -- Lias of Whitby, 147 + + -- Oolites, 185, 195 + + +V + + Variation of bones in mammals, 38 + + -- in Pterodactyles, 229 + + Variation of bones in vertebrae, 225 + + Vertebrae, caudal, 89, 92, 203 + + -- cervical, 173, 179, 203 + + -- dorsal, 86 + + Vertebral articulation, 82, 224 + + -- column, 78 + + Vulture, neck vertebrae of, 80; + tibia and fibula of, 102 + + Vomer, 147 + + Vomerine bones, 72 + + +W + + Wagler, 29 + + Wagner, Andreas, 30, 148, 231 + + Walker, J. F., 54 + + Wealden beds, Pterodactyles in, 55, 84; + bones in, 135, 136, 173 + + Weight of Pterodactyle, 106 + + Whinchat, 47 + + Whitby, 33, 135 + + Williston, Professor W. S., 75, 82, 92, 98, 105, 110 + + Willow-wren, 47 + + Wing finger, 116, 130, 133, 151, 178, 197 + + -- membrane, 32, 121, 140, and frontispiece + + -- metacarpal, 123; + in Dimorphodon, 151; + in Ornithostoma, 184; + in bats, 131 + + Wings of Dragons, 16 + + Winkler, T. C., 231 + + Woodwardian Museum, 34 + + Wood-wren, 47 + + Wrist bones, 122 + + Wuertemberg, 33 + + +Y + + Yale College Museum, 32 + + York Museum, 34, 176 + + +Z + + Zittel, Karl von, 31, 157, 165, 231 + + Zygomatic arch, 67 + + + + + PRINTED BY + WILLIAM BRENDON AND SON + PLYMOUTH + + + + + +End of the Project Gutenberg EBook of Dragons of the Air, by H. G. Seeley + +*** END OF THIS PROJECT GUTENBERG EBOOK DRAGONS OF THE AIR *** + +***** This file should be named 35316.txt or 35316.zip ***** +This and all associated files of various formats will be found in: + http://www.gutenberg.org/3/5/3/1/35316/ + +Produced by Chris Curnow and the Online Distributed +Proofreading Team at http://www.pgdp.net (This file was +produced from images generously made available by The +Internet Archive) + + +Updated editions will replace the previous one--the old editions +will be renamed. + +Creating the works from public domain print editions means that no +one owns a United States copyright in these works, so the Foundation +(and you!) can copy and distribute it in the United States without +permission and without paying copyright royalties. Special rules, +set forth in the General Terms of Use part of this license, apply to +copying and distributing Project Gutenberg-tm electronic works to +protect the PROJECT GUTENBERG-tm concept and trademark. Project +Gutenberg is a registered trademark, and may not be used if you +charge for the eBooks, unless you receive specific permission. If you +do not charge anything for copies of this eBook, complying with the +rules is very easy. You may use this eBook for nearly any purpose +such as creation of derivative works, reports, performances and +research. They may be modified and printed and given away--you may do +practically ANYTHING with public domain eBooks. Redistribution is +subject to the trademark license, especially commercial +redistribution. + + + +*** START: FULL LICENSE *** + +THE FULL PROJECT GUTENBERG LICENSE +PLEASE READ THIS BEFORE YOU DISTRIBUTE OR USE THIS WORK + +To protect the Project Gutenberg-tm mission of promoting the free +distribution of electronic works, by using or distributing this work +(or any other work associated in any way with the phrase "Project +Gutenberg"), you agree to comply with all the terms of the Full Project +Gutenberg-tm License (available with this file or online at +http://gutenberg.org/license). + + +Section 1. General Terms of Use and Redistributing Project Gutenberg-tm +electronic works + +1.A. By reading or using any part of this Project Gutenberg-tm +electronic work, you indicate that you have read, understand, agree to +and accept all the terms of this license and intellectual property +(trademark/copyright) agreement. If you do not agree to abide by all +the terms of this agreement, you must cease using and return or destroy +all copies of Project Gutenberg-tm electronic works in your possession. +If you paid a fee for obtaining a copy of or access to a Project +Gutenberg-tm electronic work and you do not agree to be bound by the +terms of this agreement, you may obtain a refund from the person or +entity to whom you paid the fee as set forth in paragraph 1.E.8. + +1.B. "Project Gutenberg" is a registered trademark. It may only be +used on or associated in any way with an electronic work by people who +agree to be bound by the terms of this agreement. There are a few +things that you can do with most Project Gutenberg-tm electronic works +even without complying with the full terms of this agreement. See +paragraph 1.C below. There are a lot of things you can do with Project +Gutenberg-tm electronic works if you follow the terms of this agreement +and help preserve free future access to Project Gutenberg-tm electronic +works. See paragraph 1.E below. + +1.C. The Project Gutenberg Literary Archive Foundation ("the Foundation" +or PGLAF), owns a compilation copyright in the collection of Project +Gutenberg-tm electronic works. Nearly all the individual works in the +collection are in the public domain in the United States. If an +individual work is in the public domain in the United States and you are +located in the United States, we do not claim a right to prevent you from +copying, distributing, performing, displaying or creating derivative +works based on the work as long as all references to Project Gutenberg +are removed. Of course, we hope that you will support the Project +Gutenberg-tm mission of promoting free access to electronic works by +freely sharing Project Gutenberg-tm works in compliance with the terms of +this agreement for keeping the Project Gutenberg-tm name associated with +the work. You can easily comply with the terms of this agreement by +keeping this work in the same format with its attached full Project +Gutenberg-tm License when you share it without charge with others. + +1.D. The copyright laws of the place where you are located also govern +what you can do with this work. Copyright laws in most countries are in +a constant state of change. If you are outside the United States, check +the laws of your country in addition to the terms of this agreement +before downloading, copying, displaying, performing, distributing or +creating derivative works based on this work or any other Project +Gutenberg-tm work. The Foundation makes no representations concerning +the copyright status of any work in any country outside the United +States. + +1.E. Unless you have removed all references to Project Gutenberg: + +1.E.1. The following sentence, with active links to, or other immediate +access to, the full Project Gutenberg-tm License must appear prominently +whenever any copy of a Project Gutenberg-tm work (any work on which the +phrase "Project Gutenberg" appears, or with which the phrase "Project +Gutenberg" is associated) is accessed, displayed, performed, viewed, +copied or distributed: + +This eBook is for the use of anyone anywhere 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 + +1.E.2. If an individual Project Gutenberg-tm electronic work is derived +from the public domain (does not contain a notice indicating that it is +posted with permission of the copyright holder), the work can be copied +and distributed to anyone in the United States without paying any fees +or charges. If you are redistributing or providing access to a work +with the phrase "Project Gutenberg" associated with or appearing on the +work, you must comply either with the requirements of paragraphs 1.E.1 +through 1.E.7 or obtain permission for the use of the work and the +Project Gutenberg-tm trademark as set forth in paragraphs 1.E.8 or +1.E.9. + +1.E.3. If an individual Project Gutenberg-tm electronic work is posted +with the permission of the copyright holder, your use and distribution +must comply with both paragraphs 1.E.1 through 1.E.7 and any additional +terms imposed by the copyright holder. Additional terms will be linked +to the Project Gutenberg-tm License for all works posted with the +permission of the copyright holder found at the beginning of this work. + +1.E.4. Do not unlink or detach or remove the full Project Gutenberg-tm +License terms from this work, or any files containing a part of this +work or any other work associated with Project Gutenberg-tm. + +1.E.5. Do not copy, display, perform, distribute or redistribute this +electronic work, or any part of this electronic work, without +prominently displaying the sentence set forth in paragraph 1.E.1 with +active links or immediate access to the full terms of the Project +Gutenberg-tm License. + +1.E.6. You may convert to and distribute this work in any binary, +compressed, marked up, nonproprietary or proprietary form, including any +word processing or hypertext form. However, if you provide access to or +distribute copies of a Project Gutenberg-tm work in a format other than +"Plain Vanilla ASCII" or other format used in the official version +posted on the official Project Gutenberg-tm web site (www.gutenberg.org), +you must, at no additional cost, fee or expense to the user, provide a +copy, a means of exporting a copy, or a means of obtaining a copy upon +request, of the work in its original "Plain Vanilla ASCII" or other +form. Any alternate format must include the full Project Gutenberg-tm +License as specified in paragraph 1.E.1. + +1.E.7. Do not charge a fee for access to, viewing, displaying, +performing, copying or distributing any Project Gutenberg-tm works +unless you comply with paragraph 1.E.8 or 1.E.9. + +1.E.8. You may charge a reasonable fee for copies of or providing +access to or distributing Project Gutenberg-tm electronic works provided +that + +- You pay a royalty fee of 20% of the gross profits you derive from + the use of Project Gutenberg-tm works calculated using the method + you already use to calculate your applicable taxes. The fee is + owed to the owner of the Project Gutenberg-tm trademark, but he + has agreed to donate royalties under this paragraph to the + Project Gutenberg Literary Archive Foundation. Royalty payments + must be paid within 60 days following each date on which you + prepare (or are legally required to prepare) your periodic tax + returns. Royalty payments should be clearly marked as such and + sent to the Project Gutenberg Literary Archive Foundation at the + address specified in Section 4, "Information about donations to + the Project Gutenberg Literary Archive Foundation." + +- You provide a full refund of any money paid by a user who notifies + you in writing (or by e-mail) within 30 days of receipt that s/he + does not agree to the terms of the full Project Gutenberg-tm + License. You must require such a user to return or + destroy all copies of the works possessed in a physical medium + and discontinue all use of and all access to other copies of + Project Gutenberg-tm works. + +- You provide, in accordance with paragraph 1.F.3, a full refund of any + money paid for a work or a replacement copy, if a defect in the + electronic work is discovered and reported to you within 90 days + of receipt of the work. + +- You comply with all other terms of this agreement for free + distribution of Project Gutenberg-tm works. + +1.E.9. If you wish to charge a fee or distribute a Project Gutenberg-tm +electronic work or group of works on different terms than are set +forth in this agreement, you must obtain permission in writing from +both the Project Gutenberg Literary Archive Foundation and Michael +Hart, the owner of the Project Gutenberg-tm trademark. Contact the +Foundation as set forth in Section 3 below. + +1.F. + +1.F.1. Project Gutenberg volunteers and employees expend considerable +effort to identify, do copyright research on, transcribe and proofread +public domain works in creating the Project Gutenberg-tm +collection. Despite these efforts, Project Gutenberg-tm electronic +works, and the medium on which they may be stored, may contain +"Defects," such as, but not limited to, incomplete, inaccurate or +corrupt data, transcription errors, a copyright or other intellectual +property infringement, a defective or damaged disk or other medium, a +computer virus, or computer codes that damage or cannot be read by +your equipment. + +1.F.2. LIMITED WARRANTY, DISCLAIMER OF DAMAGES - Except for the "Right +of Replacement or Refund" described in paragraph 1.F.3, the Project +Gutenberg Literary Archive Foundation, the owner of the Project +Gutenberg-tm trademark, and any other party distributing a Project +Gutenberg-tm electronic work under this agreement, disclaim all +liability to you for damages, costs and expenses, including legal +fees. YOU AGREE THAT YOU HAVE NO REMEDIES FOR NEGLIGENCE, STRICT +LIABILITY, BREACH OF WARRANTY OR BREACH OF CONTRACT EXCEPT THOSE +PROVIDED IN PARAGRAPH 1.F.3. YOU AGREE THAT THE FOUNDATION, THE +TRADEMARK OWNER, AND ANY DISTRIBUTOR UNDER THIS AGREEMENT WILL NOT BE +LIABLE TO YOU FOR ACTUAL, DIRECT, INDIRECT, CONSEQUENTIAL, PUNITIVE OR +INCIDENTAL DAMAGES EVEN IF YOU GIVE NOTICE OF THE POSSIBILITY OF SUCH +DAMAGE. + +1.F.3. LIMITED RIGHT OF REPLACEMENT OR REFUND - If you discover a +defect in this electronic work within 90 days of receiving it, you can +receive a refund of the money (if any) you paid for it by sending a +written explanation to the person you received the work from. If you +received the work on a physical medium, you must return the medium with +your written explanation. The person or entity that provided you with +the defective work may elect to provide a replacement copy in lieu of a +refund. If you received the work electronically, the person or entity +providing it to you may choose to give you a second opportunity to +receive the work electronically in lieu of a refund. If the second copy +is also defective, you may demand a refund in writing without further +opportunities to fix the problem. + +1.F.4. Except for the limited right of replacement or refund set forth +in paragraph 1.F.3, this work is provided to you 'AS-IS' WITH NO OTHER +WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO +WARRANTIES OF MERCHANTIBILITY OR FITNESS FOR ANY PURPOSE. + +1.F.5. Some states do not allow disclaimers of certain implied +warranties or the exclusion or limitation of certain types of damages. +If any disclaimer or limitation set forth in this agreement violates the +law of the state applicable to this agreement, the agreement shall be +interpreted to make the maximum disclaimer or limitation permitted by +the applicable state law. The invalidity or unenforceability of any +provision of this agreement shall not void the remaining provisions. + +1.F.6. INDEMNITY - You agree to indemnify and hold the Foundation, the +trademark owner, any agent or employee of the Foundation, anyone +providing copies of Project Gutenberg-tm electronic works in accordance +with this agreement, and any volunteers associated with the production, +promotion and distribution of Project Gutenberg-tm electronic works, +harmless from all liability, costs and expenses, including legal fees, +that arise directly or indirectly from any of the following which you do +or cause to occur: (a) distribution of this or any Project Gutenberg-tm +work, (b) alteration, modification, or additions or deletions to any +Project Gutenberg-tm work, and (c) any Defect you cause. + + +Section 2. Information about the Mission of Project Gutenberg-tm + +Project Gutenberg-tm is synonymous with the free distribution of +electronic works in formats readable by the widest variety of computers +including obsolete, old, middle-aged and new computers. It exists +because of the efforts of hundreds of volunteers and donations from +people in all walks of life. + +Volunteers and financial support to provide volunteers with the +assistance they need, are critical to reaching Project Gutenberg-tm's +goals and ensuring that the Project Gutenberg-tm collection will +remain freely available for generations to come. In 2001, the Project +Gutenberg Literary Archive Foundation was created to provide a secure +and permanent future for Project Gutenberg-tm and future generations. +To learn more about the Project Gutenberg Literary Archive Foundation +and how your efforts and donations can help, see Sections 3 and 4 +and the Foundation web page at http://www.pglaf.org. + + +Section 3. Information about the Project Gutenberg Literary Archive +Foundation + +The Project Gutenberg Literary Archive Foundation is a non profit +501(c)(3) educational corporation organized under the laws of the +state of Mississippi and granted tax exempt status by the Internal +Revenue Service. The Foundation's EIN or federal tax identification +number is 64-6221541. Its 501(c)(3) letter is posted at +http://pglaf.org/fundraising. Contributions to the Project Gutenberg +Literary Archive Foundation are tax deductible to the full extent +permitted by U.S. federal laws and your state's laws. + +The Foundation's principal office is located at 4557 Melan Dr. S. +Fairbanks, AK, 99712., but its volunteers and employees are scattered +throughout numerous locations. Its business office is located at +809 North 1500 West, Salt Lake City, UT 84116, (801) 596-1887, email +business@pglaf.org. Email contact links and up to date contact +information can be found at the Foundation's web site and official +page at http://pglaf.org + +For additional contact information: + Dr. Gregory B. Newby + Chief Executive and Director + gbnewby@pglaf.org + + +Section 4. Information about Donations to the Project Gutenberg +Literary Archive Foundation + +Project Gutenberg-tm depends upon and cannot survive without wide +spread public support and donations to carry out its mission of +increasing the number of public domain and licensed works that can be +freely distributed in machine readable form accessible by the widest +array of equipment including outdated equipment. Many small donations +($1 to $5,000) are particularly important to maintaining tax exempt +status with the IRS. + +The Foundation is committed to complying with the laws regulating +charities and charitable donations in all 50 states of the United +States. Compliance requirements are not uniform and it takes a +considerable effort, much paperwork and many fees to meet and keep up +with these requirements. We do not solicit donations in locations +where we have not received written confirmation of compliance. To +SEND DONATIONS or determine the status of compliance for any +particular state visit http://pglaf.org + +While we cannot and do not solicit contributions from states where we +have not met the solicitation requirements, we know of no prohibition +against accepting unsolicited donations from donors in such states who +approach us with offers to donate. + +International donations are gratefully accepted, but we cannot make +any statements concerning tax treatment of donations received from +outside the United States. U.S. laws alone swamp our small staff. + +Please check the Project Gutenberg Web pages for current donation +methods and addresses. Donations are accepted in a number of other +ways including checks, online payments and credit card donations. +To donate, please visit: http://pglaf.org/donate + + +Section 5. General Information About Project Gutenberg-tm electronic +works. + +Professor Michael S. Hart is the originator of the Project Gutenberg-tm +concept of a library of electronic works that could be freely shared +with anyone. For thirty years, he produced and distributed Project +Gutenberg-tm eBooks with only a loose network of volunteer support. + + +Project Gutenberg-tm eBooks are often created from several printed +editions, all of which are confirmed as Public Domain in the U.S. +unless a copyright notice is included. Thus, we do not necessarily +keep eBooks in compliance with any particular paper edition. + + +Most people start at our Web site which has the main PG search facility: + + http://www.gutenberg.org + +This Web site includes information about Project Gutenberg-tm, +including how to make donations to the Project Gutenberg Literary +Archive Foundation, how to help produce our new eBooks, and how to +subscribe to our email newsletter to hear about new eBooks. |