[2]If some vast catastrophe should today blot out all the mammalian races including man, and the birds, but leave the lizards and other reptiles still surviving, with the lower animals and plants, we might well expect the lizards in the course of geologic periods to evolve into a great and varied land fauna like the Dinosaurs of the Mesozoic Era.
[2]If some vast catastrophe should today blot out all the mammalian races including man, and the birds, but leave the lizards and other reptiles still surviving, with the lower animals and plants, we might well expect the lizards in the course of geologic periods to evolve into a great and varied land fauna like the Dinosaurs of the Mesozoic Era.
[3]The ancestral types have four complete toes, but in the true Theropoda the inner digit is reduced to a small incomplete remnant, its claw reversed and projecting at the back of the foot, as in birds.
[3]The ancestral types have four complete toes, but in the true Theropoda the inner digit is reduced to a small incomplete remnant, its claw reversed and projecting at the back of the foot, as in birds.
The sharp teeth, compressed and serrated like a palaeolithic spear point, and the powerful sharp-pointed curved claws on the feet, prove the carnivorous habits of these dinosaurs. The well-finished joints, dense texture of the hollow bones and strongly marked muscle-scars indicate that they were active and powerful beasts of prey. They range from small slender animals up to the giganticTyrannosaurusequalling the modern elephant in bulk. They were half lizard, half bird in proportions, combining the head, the short neck and small fore limbs and long snaky tail of the lizard with the short, compact body, long powerful hind limbs and three-toed feet of the bird. The skin was probably either naked or covered with horny scales as in lizards and snakes; at all events it was not armor-plated as in the crocodile.[4]They walked or ran upon the hind legs; in many of them the fore limbs are quite unfittedfor support of the body and must have been used solely in fighting or tearing their prey.
Fig. 10.: Hind Limb of Allosaurus.Fig. 10.—Hind Limb of Allosaurus, Dr. J.L. Wortman standing to one side. Dr. Wortman is one of the most notable and successful collectors of fossil vertebrates and was in charge of the Museum's field work in this department from 1891-1898.
Fig. 10.—Hind Limb of Allosaurus, Dr. J.L. Wortman standing to one side. Dr. Wortman is one of the most notable and successful collectors of fossil vertebrates and was in charge of the Museum's field work in this department from 1891-1898.
The huge size of some of these Mesozoic beasts of prey finds no parallel among their modern analogues. It is only among marine animals that we find predaceous types of such gigantic size. But among the carnivorous dinosaurs we fail to find any indications of aquatic or even amphibious habits. They might indeed wade in the water, but they could hardly be at home in it, for they were clearly not good swimmers. We must suppose that they were dry land animals or at most swamp dwellers.
Dinosaur Footprints.The ancestors of the Theropoda appear first in the Triassic period, already of largesize, but less completely bipedal than their successors. Incomplete skeletons have been found in the Triassic formations of Germany[5]but in this country they are chiefly known from the famous fossil footprints (or "bird-tracks" as they were at first thought to be), found in the flagstone quarries at Turner's Falls on the Connecticut River, in the vicinity of Boonton, New Jersey, and elsewhere. These tracks are the footprints of numerous kinds of dinosaurs, large and small, mostly of the carnivorous group, which lived in that region in the earlier part of the Age of Reptiles, and much has been learned from them as to the habits of the animals that made them. The tracks ascribed to carnivorous dinosaurs run in series with narrow tread, short or long steps, here and there a light impression of tail or forefoot and occasionally the mark of the shank and pelvis when the animal settled back and squatted down to rest a moment. The modern crocodiles when they lift the body off the ground, waddle forward with the short limbs wide apart, and even the lizards which run on their hind legs have a rather wide tread. But these dinosaurs ran like birds, setting one foot nearly in front of the other, so that the prints of right and left feet are nearly in a straight line. This was on account of their greater length of limb, which made it easy for them toswing the foot directly underneath the body at each step like mammals and birds, and thus maintain an even balance, instead of wabbling from side to side as short legged animals are compelled to do.
Of the animals that made these innumerable tracks the actual remains found thus far in this country are exceedingly scanty. Two or three incomplete skeletons of small kinds are in the Yale Museum, of whichAnchisaurusis the best known.
Megalosaurus.Fragmentary remains of this huge carnivorous dinosaur were found in England nearly a century ago, and the descriptions by Dean Buckland and Sir Richard Owen and the restorations due to the imaginative chisel of Waterhouse Hawkins, have made it familiar to most English readers. Unfortunately it was, and still remains, very imperfectly known. It was very closely related to the AmericanAllosaurusand unquestionably similar in appearance and habits.[6]
The following extract is from the American Museum Journal for January 1908.[7]
"Although smaller than its huge contemporary Brontosaurus, this animal is of gigantic proportions being 34 feet 2 inches in length, and 8 feet 3 inches high."
Fig. 11.: Mounted Skeleton of Allosaurus in the American Museum.After OsbornFig. 11.—Mounted Skeleton of Allosaurus in the American Museum.
After Osborn
Fig. 11.—Mounted Skeleton of Allosaurus in the American Museum.
History of the Allosaurus Skeleton."This rare and finely preserved skeleton was collected by Mr. F.F. Hubbell in October 1879, in the Como Bluffs near Medicine Bow, Wyoming, the richest locality in America for dinosaur skeletons, and is a part of the great collection of fossil reptiles, amphibians and fishes gathered together by the late Professor E.D. Cope, and presented to the American Museum in 1899 by President Jesup.
"Shortly after the Centennial Exposition (1876) it had been planned that Professor Cope's collection of fossils should form part of a great public museum in Fairmount Park, Philadelphia, the city undertaking the cost of preparing and exhibiting the specimens, an arrangement similar to that existing between the American Museum and the City of New York.[8]
"The plan, however, fell through, and the greater part of this magnificent collection remained in storage in the basement of Memorial Hall in Fairmount Park, for the next twenty years. From time to time Professor Cope removed parts of the collection to his private museum in Pine Street, for purposes of study and scientific description. He seems, however, to have had no idea of the perfection and value of this specimen. In 1899 when the collection was purchased from his executors by Mr. Jesup, the writer went to Philadelphia under the instructions of Professor Osborn, Curator of Fossil Vertebrates, to superintend the packing and removal tothe American Museum. At that time the collection made by Hubbell was still in Memorial Hall, and the boxes were piled up just as they came in from the West, never having been unpacked. Professor Cope's assistant, Mr. Geismar, informed the writer that Hubbell's collection was mostly fragmentary and not of any great value. Mr. Hubbell's letters from the field unfortunately were not preserved, but it is likely that they did not make clear what a splendid find he had made, and as some of his earlier collections had been fragmentary and of no great interest, the rest were supposed to be of the same kind.
"When the Cope Collection was unpacked at the American Museum, this lot of boxes, not thought likely to be of much interest, was left until the last, and not taken in hand until 1902 or 1903. But when this specimen was laid out, it appeared that a treasure had come to light. Although collected by the crude methods of early days, it consisted of the greater part of the skeleton of a single individual, with the bones in wonderfully fine preservation, considering that they had been buried for say eight million years. They were dense black, hard and uncrushed, even better preserved and somewhat more complete than the two fine skeletons of Allosaurus from Bone-Cabin Quarry, the greatest treasures that this famous quarry had supplied. The great carnivorous dinosaurs are much rarer than the herbivorous kinds, and these three skeletons are the most complete that have ever been found. In all theyears of energetic exploration that the late Professor Marsh devoted to searching for dinosaurs in the Jurassic and Cretaceous formations of the West, he did not obtain any skeletons of carnivorous kinds anywhere near as complete as these, and their anatomy was in many respects unknown or conjectural. By comparison of the three Allosaurus skeletons with one another and with other specimens of carnivorous dinosaurs of smaller size in this and other museums, particularly in the National Museum and the Kansas University Museum, we have been able to reconstruct the missing parts of the Cope specimen with very little possibility of serious error."
Evidence for Combining and Posing this Mount."An incomplete specimen of Brontosaurus, found by Doctor Wortman and Professor W.C. Knight of the American Museum Expedition of 1897, had furnished interesting data as to the food and habits of Allosaurus, which were confirmed by several other fragmentary specimens obtained later in the Bone-Cabin Quarry. In this Brontosaurus skeleton several of the bones, especially the spines of the tail vertebrae, when found in the rock, looked as if they had been scored and bitten off, as though by some carnivorous animal which had either attacked the Brontosaurus when alive, or had feasted upon the carcass. When the Allosaurus jaw was compared with these score marks, it was found to fit them exactly, the spacing of the scratches being the same as the spacing of the teeth. Moreover, on taking out theBrontosaurus vertebrae from the quarry, a number of broken off teeth of Allosaurus were found lying beside them. As no other remains of Allosaurus or any other animal were intermingled with the Brontosaurus skeleton, the most obvious explanation was that these teeth were broken off by an Allosaurus while devouring the Brontosaurus carcass. Many of the bones of other herbivorous dinosaurs found in the Bone-Cabin Quarry were similarly scored and bitten off, and the teeth of Allosaurus were also found close to them.
"With these data at hand the original idea was conceived of combining these two skeletons, both from the same formation and found within a few miles of each other, to represent what must actually have happened to them in the remote Jurassic period, and mount the Allosaurus skeleton standing over the remains of a Brontosaurus in the attitude of feeding upon its carcass. Some modifications were made in the position to suit the exigencies of an open mount, and to accommodate the pose to the particular action; the head of the animal was lifted a little, one hind foot planted upon the carcass, while the other, resting upon the ground bears most of the weight. The fore feet, used in these animals only for fighting or for tearing their prey, not for support, are given characteristic attitudes, and the whole pose represents the Allosaurus devouring the carcass and raising head and fore foot in a threatening manner as though to drive away intruders. The balance of the various parts was carefully studied andadjusted under direction of the curator. The preparation and mounting of the specimen were done by Mr. Adam Hermann, head preparator, and his assistants, especially Messrs. Falkenbach and Lang.
Fig. 12.: Restoration of Allosaurus by C.R. Knight.After OsbornFig. 12.—Restoration of Allosaurus by C.R. Knight.
After Osborn
Fig. 12.—Restoration of Allosaurus by C.R. Knight.
"As now exhibited in the Dinosaur Hall, this group gives to the imaginative observer a most vivid picture of a characteristic scene in that bygone age, millions of years ago, when reptiles were the lords of creation, and 'Nature, red in tooth and claw' had lost none of her primitive savagery, and the era of brute force and ferocity showed little sign of the gradual amelioration which was to come to pass in future ages through the predominance of superior intelligence."
Appearance and Habits of Allosaurus.A study of the mechanism of the Allosaurus skeleton shows us in the first place that the animal is balanced on the hindlimbs, the long heavy tail making an adequate counterpoise for the short compact body and head. The hind limbs are nine feet in length when extended, about equal to the length of the body and neck, and the bones are massively proportioned. When the thigh bone is set in its normal position, as indicated by the position of the scars and processes for attachment of the principal muscles (see under Brontosaurus for the method used to determine this), the knee bends forward as in mammals and birds, not outward as in most modern reptiles. The articulations of the foot bones show that the animal rested upon the ends of the metapodials, as birds and many mammals do, not upon the sole of the foot like crocodiles or lizards. The flat vertebral joints show that the short compact body was not as flexible as the longer body of crocodiles or lizards, in which the articulations are of the ball and socket type showing that in them this region was very flexible. The tail also shows a limited flexibility. It could not be curled or thrown over the back, but projected out behind the animal, swinging from side to side or up and down as much as was needed for balance. The curvature of the ribs shows that the body was narrow and deep, unlike the broad flattened body of the crocodile or the less flattened but still broad body of the lizard. The loose hung jaw, articulated far back, shows by the set of its muscles that it was capable of an enormous gape; while in the skull there is evidence of a limited movement of the upper jaw on the cranial portion, intendedprobably to assist in the swallowing of large objects, like the double jointed jaw of a snake.
As to the nature of the skin we have no exact knowledge. We may be sure that it had no bony armor like the crocodile, for remains of any such armor could not fail to be preserved with the skeletons, as it always is in fossil crocodiles or turtles. Perhaps it was scaly like the skin of lizards and snakes, for the horny scales of the body are not preserved in fossil skeletons of these reptiles. But if so we might expect from the analogy of the lizard that the scales of the head would be ossified and preserved in the fossil; and there is nothing of this kind in the Carnivorous Dinosaurs. We can exclude feathers from consideration, for these dinosaurs have no affinities to birds, and there is no evidence for feathers in any dinosaur. Probably the best evidence is that of the Trachodon or duck-billed dinosaur although this animal was but distantly related to the Allosaurus. In Trachodon (see p. 94), we know that the skin bore neither feathers nor overlapping scales but had a curiously patterned mosaic of tiny polygonal plates and was thin and quite flexible. Some such type of skin as this, in default of better evidence, we may ascribe to the Allosaurus.
Fig. 13.: View in the Hell Creek badlands in central Montana, where the Tyrannosaurus skeleton was found.Fig. 13.—View in the Hell Creek badlands in central Montana, where the Tyrannosaurus skeleton was found.
Fig. 13.—View in the Hell Creek badlands in central Montana, where the Tyrannosaurus skeleton was found.
As to its probable habits, it is safe to infer (see p. 33), that it was predaceous, active and powerful, and adapted to terrestrial life. Its methods of attack and combat must have been more like those of modern reptiles than the more intelligent methods of themammalian carnivore. The brain cast of Allosaurus indicates a brain of similar type and somewhat inferior grade to that of the modern crocodile or lizard, and far below the bird or mammal in intelligence. The keen sense of smell of the mammal, the keen vision of the bird, the highly developed reasoning power of both, were absent in the dinosaur as in the lizard or crocodile. We may imagine the Allosaurus lying in wait, watching his prey until its near approach stimulates him into a semi-instinctive activity; then a sudden swift rush, a fierce snap of the huge jaws and a savage attack with teeth and claws until the victim is torn in pieces or swallowed whole. But the stealthy, persistent tracking of the cat or weasel tribe, the intelligent generalship ofthe wolf pack, the well planned attack at the most vulnerable point in the prey, characteristic of all the predaceous mammals, would be quite impossible to the dinosaur. By watching the habits of modern reptiles we may gain a much better idea of his capacities and limitations than if we judge only from the efficiency of his teeth and claws, and forget the inferior intelligence that animated these terrible weapons.
The "Tyrant Saurian" as Professor Osborn has named him, was the climax of evolution of the giant flesh-eating dinosaurs. It reached a length of forty-seven feet, and in bulk must have equalled the mammoth or the mastodon or the largest living elephants. The massive hind limbs, supporting the whole weight of the body, exceeded the limbs of the great proboscideans in bulk, and in a standing position the animal was eighteen to twenty feet high, as against twelve for the largest African elephants or the southern mammoth. The head (see frontispiece) is 4 feet 3 inches long, 3 ft. 4 inches deep, and 2 ft. 9 inches wide; the long deep powerful jaws set with teeth from 3 to 6 inches long and an inch wide. To this powerful armament was added the great sharp claws of the hind feet, and probably the fore feet, curved like those of eagles, but six or eight inches in length.
During ten years explorations in the Western Cretaceous formations, Mr. Brown has secured for the Museum three skeletons of this magnificent dinosaur,incomplete, but finely preserved. The first, found in 1900, included the jaws, a large part of backbone and ribs, and some limb bones. The second included most of skull and jaws, backbone, ribs and pelvis and the hind limbs and feet, but not tail. The third consisted of a perfect skull and jaws, the backbone, ribs, pelvis and nearly all of the tail, but no limbs. From these three specimens it has been possible to reconstruct the entire skeleton. The exact construction of the fore feet is the only doubtful part. The fore-limb is very small relatively to the huge size of the animal, but probably was constructed much as in theAllosauruswith two or three large curved claws, the inner claw opposing the others.
Fig. 14.: Quarry from which the Tyrannosaurus skeleton was taken. American Museum camp in foreground.Fig. 14.—Quarry from which theTyrannosaurusskeleton was taken. American Museum camp in foreground.
Fig. 14.—Quarry from which theTyrannosaurusskeleton was taken. American Museum camp in foreground.
The missing parts of the two best skeletons have been restored, and with the help of two small models of the skeleton, a group has been made ready for mounting as the central piece of the proposed Cretaceous Dinosaur Hall. One of the skeletons is temporarily placed in the centre of the Quaternary Hall, space for it in the present Dinosaur Hall being lacking. Following is Professor Osborn's description of the preparation of this group:[9]
"The mounting of these two skeletons presents mechanical problems of very great difficulty. The size and weight of the various parts are enormous. The height of the head in the standing position reaches from 18 to 20 feet above the ground; the knee joint alone reaches 6 feet above the ground. All the bones are massive; the pelvis, femur and skull are extremely heavy. Experience withBrontosaurusand with other large dinosaurs proves that it is impossible to design a metallic frame in the right pose in advance of assembling the parts. Even a scale restoration model of the animal as a whole does not obviate the difficulty.
"Accordingly in preparing to mountTyrannosaurusfor exhibition a new method has been adopted, namely, toprepare a scale model of every bone in the skeletonand mount this small skeleton with flexible joints and parts so that all studies and experiments as to pose can be made with the models.
"This difficult and delicate undertaking was entrusted to Mr. Erwin Christman of the artistic staff of the Department of Vertebrate Palaeontology of the Museum, who has prepared two very exact models to a one-sixth scale, representing our two skeletons ofTyrannosaurus rex, which fortunately are of exactly the same size. A series of three experiments by Mr. Christman on the pose ofTyrannosaurus, under the direction of the author and Curator Matthew, were not satisfactory. The advice of Mr. Raymond L. Ditmars, Curator of Reptiles in the New York Zoological Park, was sought and we thus obtained the fourth pose, which is shown in the photographs published herewith.
Fig. 15.: Model of Tyrannosaurus group for the Cretaceous Dinosaur Hall.Fig. 15.—Model ofTyrannosaurusgroup for the Cretaceous Dinosaur Hall.
Fig. 15.—Model ofTyrannosaurusgroup for the Cretaceous Dinosaur Hall.
"The fourth pose or study, for the proposed full sized mount, is that of two reptiles of the same size attracted to the same prey. One reptile is crouching over its prey (which is represented by a portion of a skeleton).The object of this depressed pose is to bring the perfectly preserved skull and pelvis very near the ground within easy reach of the visiting observer. The second reptile is advancing, and attains very nearly the full height of the animal. The general effect of this group is the best that can be had and is very realistic, particularly the crouching figure. A fifth study will embody some further changes. The upright figure is not well balanced and will be more effective with the feet closer together, the legs straighter and the body more erect. These reptiles have a series of strong abdominal ribs not shown in the models. The fourth position places the pelvis in an almost impossible position as will be noted from the ischium and pubis.
"The lateral view of this fourth pose represents the animals just prior to the convulsive single spring and tooth grip which distinguishes the combat of reptiles from that of all mammals, according to Mr. Ditmars.
"The rear view of the standing skeleton displays the peculiarly avian structure of the iliac junction with the sacral plate, characteristic of these very highly specialized dinosaurs, also the marked reduction of the upper end of the median metatarsal bone, which formerly was believed to be peculiar toOrnithomimus."
This model of the group is on exhibition with the mounted skeleton.
As compared with its predecessorAllosaurus, theTyrannosaurusis much more massively proportioned throughout. The skull is more solid, the jaws muchdeeper and more powerful, the fore limb much smaller, the tail shorter, the hind limb straighter and the foot bones more compacted so that the animal was more strictly "digitigrade," approaching the ostriches more closely in this particular.
Fig. 16.: Skeleton of Tyrannosaurus in comparison with human skeleton.Fig. 16.—Skeleton of Tyrannosaurus in comparison with human skeleton.
Fig. 16.—Skeleton of Tyrannosaurus in comparison with human skeleton.
This animal probably reached the maximum of size and of development of teeth and claws of which its type of animal mechanism was capable. Its bulk precluded quickness and agility. It must have been designed to attack and prey upon the ponderous and slow moving Horned and Armored Dinosaurs with which its remains are found, and whose massive cuirass and weapons of defense are well matched with its teeth and claws. The momentum of its huge body involved a seemingly slow and lumbering action, an inertia of its movements, difficult to start and difficult to shift or to stop. Such movements are widely different from the agile swiftness which we naturally associate with a beast of prey. But an animal which exceeds an average elephant in bulk, no matter what its habits, is compelled by the laws of mechanics to the ponderous movements appropriate to its gigantic size. These movements, directed and controlled by a reptilian brain, must needs be largely automatic and instinctive. We cannot doubt indeed that the Carnivorous Dinosaurs developed, along with their elaborately perfected mechanism for attack, an equally elaborate series of instincts guiding their action to effective purpose; and a complex series of automatic responses to the stimulusafforded by the sight and action of their prey might very well mimic intelligent pursuit and attack, always with certain limits set by the inflexible character of such automatic adjustments. But no animal as large asTyrannosauruscould leap or spring upon another, and its slow stride quickening into a swift resistless rush, might well end in unavoidable impalement upon the great horns ofTriceratops, futile weapons against a small and active enemy, but designed no doubt to meet just such attacks as these. A true picture of these combats of titans of the ancient world we cannot draw; perhaps we will never be able to reconstruct it. But the above considerations may serve to show how widely it would differ from the pictures based upon any modern analogies.
One may well inquire why it is that no such gigantic carnivora have evolved among the mammalian land animals. The largest predaceous quadrupeds living today are the lion and tiger. The bears although some of them are much larger, are not generally carnivorous, except for the polar bear, which is partly aquatic, preying chiefly upon seals and fish. There are indeed carnivorous whales of gigantic size, but no very large land carnivore. There were, it is true, during the Tertiary and Pleistocene, lions and other carnivores considerably larger than the living species. But none of them attained the size of their largest herbivorous contemporaries, or even approached it. Among the dinosaurs on the other hand we find that—settingaside Brontosaurus and its allies as aquatic—the predaceous kinds equalled or exceeded the largest of the herbivorous sorts. The difference is striking, and it does not seem likely that it is merely accidental.
The explanation lies probably in the fact that the large herbivorous mammals are much more intelligent and active, and would be able to use their weapons of defense so as to defy the attacks of relatively slow moving giant beasts of prey, as they do also the more active but less powerful assaults of smaller ones. The elephant or the rhinoceros is in fact practically immune from the attacks of carnivora, and would still be so were the carnivora to increase in size. The large modern carnivora prey upon herbivores of medium or smaller size, which they are active enough to surprise or run down. Carnivora of much larger size would be too slow and heavy in movements to catch small prey, while the larger herbivores by intelligent use of their defensive weapons could still fend them off successfully. In consequence giant carnivores would find no field for action in the Cenozoic world, and hence they have not been evolved.
But the giant herbivorous dinosaurs, well armed or well defended though they were, had not the intelligence to use those weapons effectively under all circumstances. Thus they might be successfully attacked, at least sometimes, by the powerful although slow moving Megalosaurians.
The suggestion has also been made that these giantcarnivores were carrion-eaters rather than truly predaceous. The hypothesis can hardly be effectively supported nor attacked. It is presented as a possible alternate.
Albertosaurus.Closely allied to theTyrannosaurusbut smaller, about equal in size toAllosaurus, was theAlbertosaurusof the Edmonton formation in Canada. It is somewhat older than the Tyrannosaur although still of the late Cretacic period, and may have been ancestral to it. A fine series of limbs and feet as also skull, tail, etc., are in the Museum's collections. At or about this time carnivorous dinosaurs of slightly smaller size are known to have inhabited New Jersey; a fragmentary skeleton of one secured by Professor Cope in 1869 was described asLaelaps(=Dryptosaurus).[10]
Ornitholestes.In contrast with theAllosaurusandTyrannosaurusthis skeleton represents the smaller and more agile carnivorous dinosaurs which preyed upon the lesser herbivorous reptiles of the period. These little dinosaurs were probably common during all the Age of Reptiles, much as the smaller quadrupeds are today, but skulls or skeletons are rarely found in the formations known to us. TheAnchisaurus,Podokesaurusand other genera of the Triassic Period have left innumerable tracks upon the sandy shales of the Newark formation, but only two or three skeletons areknown. A cast of one of them is exhibited here. The original is preserved in the Yale Museum. In the succeeding Jurassic Period we have theCompsognathus, smallest of known dinosaurs, and thisOrnitholestessome six feet long. A cast of theCompsognathusskeleton is shown, the original found in the lithographic limestone of Solenhofen is preserved in the Munich Museum. TheOrnitholestesis from the Bone-Cabin Quarry in Wyoming. The forefoot with its long slender digits is supposed to have been adapted for grasping an active and elusive prey, and the name (Ornitho-lestes= bird-robber) indicates that that prey may sometimes have been the primitive birds which were its contemporaries. In the Cretacic Period, there were also small and medium sized carnivorous dinosaurs, contemporary with the gigantic kinds; a complete skeleton ofOrnithomimusat the entranceto the Dinosaur Hall finely illustrates this group. In appearance most of these small dinosaurs must have suggested long-legged bipedal lizards, running and walking on their hind limbs, with the long tail stretched out behind to balance the body. From what we know of their tracks it seems that they walked or ran with a narrow treadway, the footsteps almost in the middle line of progress. They did not hop like perching birds, nor did they waddle like most living reptiles. Occasionally the tail or fore feet touched the ground as they walked; and when they sat down, they rested on theend of the pubic bones and on the tail. So much we can infer from the footprint impressions. The general appearance is shown in the restorations ofOrnitholestes,CompsognathusandAnchisaurusby Charles Knight.
Fig. 17.: Skeleton of Ornitholestes a small carnivorous dinosaur of the Jurassic period.Fig. 17.—Skeleton ofOrnitholestesa small carnivorous dinosaur of the Jurassic period. American Museum No. 619.
Fig. 17.—Skeleton ofOrnitholestesa small carnivorous dinosaur of the Jurassic period. American Museum No. 619.
Fig. 18.: Restoration of Ornitholestes.After OsbornFig. 18.—Restoration ofOrnitholestes, by C.R. Knight under direction of Professor Osborn.
After Osborn
Fig. 18.—Restoration ofOrnitholestes, by C.R. Knight under direction of Professor Osborn.
Ornithomimus.The skeleton of this animal from the Cretacic of Alberta was found by the Museum expedition of 1914. It is exceptionally complete, and has been mounted as a panel, in position as it lay in the rock, and with considerable parts of the original sandstone matrix still adherent. The long slender limbs, long neck, small head and toothless jaws are all singularly bird-like, and afford a striking contrast to the Tyrannosaurus. At the time of writing, its adaptation and relationships have not yet been thoroughly investigated.
Fig. 19.: Mounted Skeleton of Brontosaurus in the American Museum.Fig. 19.—Mounted Skeleton of Brontosaurus in the American Museum.
Fig. 19.—Mounted Skeleton of Brontosaurus in the American Museum.
[4]This is still doubtful inTyrannosaurus. A number of very curious plates were found with one specimen in a quarry. B. Brown, 1913.
[4]This is still doubtful inTyrannosaurus. A number of very curious plates were found with one specimen in a quarry. B. Brown, 1913.
[5]Quite recently a series of more or less complete skeletons have been secured from the upper Triassic (Keuper) near Halberstadt in Germany. They are not true Megalosaurians, but primitive types (Pachypodosauria) ancestral to both these and the Sauropoda. Probably many of the Connecticut footprints were made by animals of this primitive group.Anchisauruscertainly belongs to it.
[5]Quite recently a series of more or less complete skeletons have been secured from the upper Triassic (Keuper) near Halberstadt in Germany. They are not true Megalosaurians, but primitive types (Pachypodosauria) ancestral to both these and the Sauropoda. Probably many of the Connecticut footprints were made by animals of this primitive group.Anchisauruscertainly belongs to it.
[6]It is evidently "the dinosaur" of Sir Conan Doyle's "Lost World" but the vivid description which the great English novelist gives of its appearance and habits, based probably upon the Hawkins restoration, is not at all in accord with inferences from what is now known of these animals. See p. 44.
[6]It is evidently "the dinosaur" of Sir Conan Doyle's "Lost World" but the vivid description which the great English novelist gives of its appearance and habits, based probably upon the Hawkins restoration, is not at all in accord with inferences from what is now known of these animals. See p. 44.
[7]Allosaurus, a carnivorous Dinosaur, and its Prey. By W.D. Matthew. Am. Mus. Nat. Hist. Jour. Vol. viii, pp. 3-5, pl. 1.
[7]Allosaurus, a carnivorous Dinosaur, and its Prey. By W.D. Matthew. Am. Mus. Nat. Hist. Jour. Vol. viii, pp. 3-5, pl. 1.
[8]The cost of preparation is now defrayed by the Museum.
[8]The cost of preparation is now defrayed by the Museum.
[9]Tyrannosaurus, Restoration and Model of the Skeleton. By Henry Fairfield Osborn. Bull. Amer. Mus. Nat. Hist., 1913, vol. xxxii, art. iv, pp. 91-92.
[9]Tyrannosaurus, Restoration and Model of the Skeleton. By Henry Fairfield Osborn. Bull. Amer. Mus. Nat. Hist., 1913, vol. xxxii, art. iv, pp. 91-92.
[10]Since these lines were written the Museum has secured finely preserved skeletons of two or more kinds of Carnivorous Dinosaurs from the Belly River formation in Canada.
[10]Since these lines were written the Museum has secured finely preserved skeletons of two or more kinds of Carnivorous Dinosaurs from the Belly River formation in Canada.
These were the Giant Reptiles par-excellence, for all of them were of enormous size, and some were by far the largest of all four-footed animals, exceeded in bulk only by the modern whales. In contrast to the carnivorous dinosaurs these are quadrupedal, with very small head, blunt teeth, long giraffe-like neck, elephantine body and limbs, long massive tail prolonged at the tip into a whip-lash as in the lizards. Like the elephant they have five short toes on each foot, probably buried in life in a large soft pad, but the inner digits bear large claws, blunt like those of turtles, one in the fore foot, three in the hind foot.
To this group belong the Brontosaurus and Diplodocus, the Camarasaurus, Morosaurus and other less known kinds. All of them lived during the late Jurassic and Comanchic ("Lower Cretaceous") and belong to the older of the two principal Dinosaur faunas. They were contemporaries of the Allosaurus and Megalosaurus, the Stegosaurus and Iguanodon,but unlike the Carnivorous and Beaked Dinosaurs they became wholly extinct before the Upper or true Cretacic, and left no relatives to take part in the final epoch of expansion and prosperity of the dinosaurian race at the close of the Reptilian era.
Fig. 20.: Skeletons of Brontosaurus (above) and Diplodocus (below) in the American Museum.Fig. 20.—Skeletons ofBrontosaurus(above) andDiplodocus(below) in the American Museum. The parts preserved in these specimens are shaded. Scale, 10 feet=1 inch.
Fig. 20.—Skeletons ofBrontosaurus(above) andDiplodocus(below) in the American Museum. The parts preserved in these specimens are shaded. Scale, 10 feet=1 inch.
The following description of the Brontosaurus skeleton in the American Museum was first published in the American Museum Journal of April,1905:[11]
"The Brontosaurus skeleton, the principal feature of the hall, is sixty-six feet eight inches long. (The weight of the animal when alive is estimated by W.K. Gregory at 38 tons). About one-third of the skeleton including the skull is restored in plaster modelled or cast from other incomplete skeletons. The remaining two-thirds belong to one individual, except for a part of the tail, one shoulder-blade and one hind limb, supplied from another skeleton of the same species."The skeleton was discovered by Mr. Walter Granger of the Museum expedition of 1898, about nine miles north of Medicine Bow, Wyoming. It took the whole of the succeeding summer to extract it from the rock, pack it, and ship it to the Museum. Nearly two years were consumed in removing the matrix, piecing together and cementing the brittle and shattered petrified bone, strengthening it so that it would bear handling, and restoring the missing parts of the bones in tintedplaster. The articulation and mounting of the skeleton and modelling of the missing bones took an even longer time, so that it was not until February, 1905, that the Brontosaurus was at last ready for exhibition.Fig. 21a.: Excavating the Brontosaurus skeleton.Fig. 21b.: Excavating the Brontosaurus skeleton.Fig. 21.—Excavating theBrontosaurusskeleton. The upper photograph shows the anterior ribs of one side still lying in position. The backbone is being prepared for removal, the sections each containing three vertebrae, partly cased in plaster and burlap (see chapter XI.) The lower photograph shows a later stage of progress, the blocks being undercut and nearly ready to turn over and incase the under side. Strips of wood have been pasted into each section to strengthen it."It will appear, therefore, that the collection, preparation and mounting of this gigantic fossil has been a task of extraordinary difficulty. No museum has ever before attempted to mount so large a fossil skeleton, and the great weight and fragile character of the bones made it necessary to devise especial methods to give each bone a rigid and complete support as otherwise it would soon break in pieces from its own weight. The proper articulating of the bones and posing of the limbs were equally difficult problems, for the Amphibious Dinosaurs, to which this animal belongs, disappeared from the earth long before the dawn of the Age of Mammals, and their nearest relatives, the living lizards, crocodiles, etc., are so remote from them in either proportions or habits that they are unsatisfactory guides in determining how the bones were articulated and are of but little use in posing the limbs and other parts of the body in positions that they must have taken during life. Nor among the higher animals of modern times is there one which has any analogy in appearance or habits of life to those which we have been obliged by the study of the skeleton to ascribe to the Brontosaurus."As far as the backbone and ribs were concerned, the articulating surfaces of the bones were a sufficientguide to enable us to pose this part of the skeleton properly. The limb joints, however, are so imperfect that we could not in this way make sure of having the bones in a correct position. The following method, therefore, was adopted."A dissection and thorough study was made by the writer, with the assistance of Mr. Granger, of the limbs of alligators and other reptiles, and the position, size and action of the principal muscles were carefully worked out. Then the corresponding bones of the Brontosaurus were studied, and the position and size of the corresponding muscles were worked out, so far as they could be recognized from the scars and processes preserved on the bone. The Brontosaurus limbs were then provisionally articulated and posed, and the position and size of each muscle were represented by a broad strip of paper extending from its origin to its insertion. The action and play of the muscles on the limb of the Brontosaurus could then be studied, and the bones adjusted until a proper and mechanically correct pose was reached. The limbs were then permanently mounted in these poses, and the skeleton as it stands is believed to represent, as nearly as study of the fossil enables us to know, a characteristic position that the animal actually assumed during life...."In proportions and appearance the Brontosaurus was quite unlike any living animal. It had a long thick tail like the lizards and crocodiles, a long, flexible neck like an ostrich, a thick short, slab-sided body andstraight, massive, post-like limbs suggesting the elephant, and a remarkably small head for the size of the beast. The ribs, limb-bones and tail-bones are exceptionally solid and heavy; the vertebrae of the back and neck, and the skull, on the contrary are constructed so as to combine the minimum of weight with the large surface necessary for the attachment of the huge muscles, the largest possible articulating surfaces, and the necessary strength at all points of strain. For this purpose they are constructed with an elaborate system of braces and buttresses of thin bony plates connecting the broad articulating surfaces and muscular attachments, all the bone between these thin plates being hollowed into a complicated system of air-cavities. This remarkable structure can be best seen in the unmounted skeleton ofCamarasaurus, another Amphibious Dinosaur." (The scientific nameCamarasaurus=chambered lizard, has reference to this peculiarity of construction.)"The teeth of the Brontosaurus indicate that it was an herbivorous animal, feeding on soft vegetable food. Three opinions as to the habitat of Amphibious Dinosaurs have been held by scientific authorities. The first, advocated by Professor Owen, who described the first specimens found sixty years ago (1841-60) and supported especially by Professor Cope, has been most generally adopted. This regards the animals as spending their lives entirely in shallow water, partly immersed, wading about on the bottom, or perhapsoccasionally swimming, but unable to emerge entirely upon dry land.[12]More recently, Professor Osborn has advocated the view that they resorted occasionally to the land for egg laying or other purposes, and still more recently the view has been taken by Mr. Riggs and the late Professor Hatcher that they were chiefly terrestrial animals. The writer inclines to the view of Owen and Cope, whose unequalled knowledge of comparative anatomy renders their opinion on this doubtful question especially authoritative.Fig. 22.: Restoration of Brontosaurus by C.R. Knight, under direction of Professor Osborn.After OsbornFig. 22.—Restoration of Brontosaurus by C.R. Knight, under direction of Professor Osborn."The contrast between the massive structure of the limb-bones, ribs and tail, and the light construction of the backbone, neck and skull, suggests that the animal was amphibious, living chiefly in shallow water, where it could wade about on the bottom, feeding upon the abundant vegetation of the coastal swamps and marshes, and pretty much out of reach of the powerful and active Carnivorous Dinosaurs which were its principal enemies. The water would buoy up the massive body and prevent its weight from pressing too heavily on the imperfect joints of the limb and foot bones, which were covered during life with thick cartilage, like the joints of whales, sea-lizards and other aquatic animals. If the full weight of the animal came on these imperfect joints the cartilage would yield and the endsof the bones would grind against each other, thus preventing the limb from moving without tearing the joint to pieces. The massive, solid limb and foot bones weighted the limbs while immersed in water, and served the same purpose as the lead in a diver's shoes, enabling the Brontosaurus to walk about firmly and securely under water. On the other hand, the joints of the neck and back are exceptionally broad, well fitting and covered with a much thinner surface of cartilage. The pressure was thus much better distributed over the joint, and the full weight of the part of the animal above water (reduced as it was by the cellular construction of the bones) might be borne on these joints without the cartilage giving way."Looking at the mounted skeleton we may see that if a line be drawn from the hip joint to the shoulder-blade, all the bones below this are massive, all above (including neck and head) are lightly constructed. This line may be taken to indicate the average water-line, so to speak, of this Leviathan of the Shallows. The long neck would enable the animal, however, to wade to a considerable depth, and it might forage for food either in the branches or the tops of trees, or more probably, among the soft succulent water-plants of the bottom. The row of short spoon-shaped stubby teeth around the front of the mouth would serve to bite or pull off soft leaves and water-plants, but the animal evidently could not masticate its food, and must have swallowed it without chewing as do modern reptiles and birds."The brain-case occupies only a small part of the back of the skull, so that the brain must have been small even for a reptile, and its organization (as inferred from the form of the brain-case) indicates a very low grade of intelligence. Much larger than the brain proper was the spinal cord, especially in the region of the sacrum, controlling most of the reflex and involuntary actions of the huge organism. Hence we can best regard the Brontosaurus as a great, slow-moving animal automaton, a vast storehouse of organized matter directed chiefly or solely by instinct, and to a very limited degree, if at all, by conscious intelligence. Its huge size and its imperfect organization, compared with the great quadrupeds of today, rendered its movements slow and clumsy; its small and low brain shows that it must have been automatic, instinctive and unintelligent."Composition of the Brontosaurus Skeleton."The principal specimen, No. 460, is from the Nine Mile Crossing of the Little Medicine Bow River, Wyoming. It consists of the 5th, 6th, and 8th to 13th cervical vertebrae, 1st to 9th dorsal and 3rd to 19th caudal vertebrae, all the ribs, both coracoids, parts of sacrum and ilia, both ischia and pubes, left femur and astragalus, and part of left fibula. The backbone and most of the neck of this specimen were found articulated together in the quarry, the ribs of one side in position, the remainder of the bones scattered aroundthem, and some of the tail bones weathered out on the surface."From No. 222, found at Como Bluffs, Wyo., were supplied the right scapula, 10th dorsal vertebra, and right femur and tibia."No. 339, from Bone-Cabin Quarry, Wyoming, supplied the 20th to 40th caudal vertebrae, No. 592, from the same locality the metatarsals of the right hind foot; and a few toe bones are supplied from other specimens.Fig. 23.: Skull of Diplodocus from Bone-Cabin Quarry, north of Medicine Bow, Wyoming.Fig. 23.—Skull ofDiplodocusfrom Bone-Cabin Quarry, north of Medicine Bow, Wyoming."The remainder of the skeleton is modelled in plaster, the scapula, humerus, radius and ulna from the skeleton in the Yale Museum, the rest principally from specimens in our own collections. The modelling of the skull is based partly upon specimens in the Yale Museum, but principally upon the complete skull of Morosaurus shown in another case."Mounted by A. Hermann, completed Feb. 10, 1905."
"The Brontosaurus skeleton, the principal feature of the hall, is sixty-six feet eight inches long. (The weight of the animal when alive is estimated by W.K. Gregory at 38 tons). About one-third of the skeleton including the skull is restored in plaster modelled or cast from other incomplete skeletons. The remaining two-thirds belong to one individual, except for a part of the tail, one shoulder-blade and one hind limb, supplied from another skeleton of the same species.
"The skeleton was discovered by Mr. Walter Granger of the Museum expedition of 1898, about nine miles north of Medicine Bow, Wyoming. It took the whole of the succeeding summer to extract it from the rock, pack it, and ship it to the Museum. Nearly two years were consumed in removing the matrix, piecing together and cementing the brittle and shattered petrified bone, strengthening it so that it would bear handling, and restoring the missing parts of the bones in tintedplaster. The articulation and mounting of the skeleton and modelling of the missing bones took an even longer time, so that it was not until February, 1905, that the Brontosaurus was at last ready for exhibition.
Fig. 21a.: Excavating the Brontosaurus skeleton.Fig. 21b.: Excavating the Brontosaurus skeleton.Fig. 21.—Excavating theBrontosaurusskeleton. The upper photograph shows the anterior ribs of one side still lying in position. The backbone is being prepared for removal, the sections each containing three vertebrae, partly cased in plaster and burlap (see chapter XI.) The lower photograph shows a later stage of progress, the blocks being undercut and nearly ready to turn over and incase the under side. Strips of wood have been pasted into each section to strengthen it.
Fig. 21.—Excavating theBrontosaurusskeleton. The upper photograph shows the anterior ribs of one side still lying in position. The backbone is being prepared for removal, the sections each containing three vertebrae, partly cased in plaster and burlap (see chapter XI.) The lower photograph shows a later stage of progress, the blocks being undercut and nearly ready to turn over and incase the under side. Strips of wood have been pasted into each section to strengthen it.
"It will appear, therefore, that the collection, preparation and mounting of this gigantic fossil has been a task of extraordinary difficulty. No museum has ever before attempted to mount so large a fossil skeleton, and the great weight and fragile character of the bones made it necessary to devise especial methods to give each bone a rigid and complete support as otherwise it would soon break in pieces from its own weight. The proper articulating of the bones and posing of the limbs were equally difficult problems, for the Amphibious Dinosaurs, to which this animal belongs, disappeared from the earth long before the dawn of the Age of Mammals, and their nearest relatives, the living lizards, crocodiles, etc., are so remote from them in either proportions or habits that they are unsatisfactory guides in determining how the bones were articulated and are of but little use in posing the limbs and other parts of the body in positions that they must have taken during life. Nor among the higher animals of modern times is there one which has any analogy in appearance or habits of life to those which we have been obliged by the study of the skeleton to ascribe to the Brontosaurus.
"As far as the backbone and ribs were concerned, the articulating surfaces of the bones were a sufficientguide to enable us to pose this part of the skeleton properly. The limb joints, however, are so imperfect that we could not in this way make sure of having the bones in a correct position. The following method, therefore, was adopted.
"A dissection and thorough study was made by the writer, with the assistance of Mr. Granger, of the limbs of alligators and other reptiles, and the position, size and action of the principal muscles were carefully worked out. Then the corresponding bones of the Brontosaurus were studied, and the position and size of the corresponding muscles were worked out, so far as they could be recognized from the scars and processes preserved on the bone. The Brontosaurus limbs were then provisionally articulated and posed, and the position and size of each muscle were represented by a broad strip of paper extending from its origin to its insertion. The action and play of the muscles on the limb of the Brontosaurus could then be studied, and the bones adjusted until a proper and mechanically correct pose was reached. The limbs were then permanently mounted in these poses, and the skeleton as it stands is believed to represent, as nearly as study of the fossil enables us to know, a characteristic position that the animal actually assumed during life....
"In proportions and appearance the Brontosaurus was quite unlike any living animal. It had a long thick tail like the lizards and crocodiles, a long, flexible neck like an ostrich, a thick short, slab-sided body andstraight, massive, post-like limbs suggesting the elephant, and a remarkably small head for the size of the beast. The ribs, limb-bones and tail-bones are exceptionally solid and heavy; the vertebrae of the back and neck, and the skull, on the contrary are constructed so as to combine the minimum of weight with the large surface necessary for the attachment of the huge muscles, the largest possible articulating surfaces, and the necessary strength at all points of strain. For this purpose they are constructed with an elaborate system of braces and buttresses of thin bony plates connecting the broad articulating surfaces and muscular attachments, all the bone between these thin plates being hollowed into a complicated system of air-cavities. This remarkable structure can be best seen in the unmounted skeleton ofCamarasaurus, another Amphibious Dinosaur." (The scientific nameCamarasaurus=chambered lizard, has reference to this peculiarity of construction.)
"The teeth of the Brontosaurus indicate that it was an herbivorous animal, feeding on soft vegetable food. Three opinions as to the habitat of Amphibious Dinosaurs have been held by scientific authorities. The first, advocated by Professor Owen, who described the first specimens found sixty years ago (1841-60) and supported especially by Professor Cope, has been most generally adopted. This regards the animals as spending their lives entirely in shallow water, partly immersed, wading about on the bottom, or perhapsoccasionally swimming, but unable to emerge entirely upon dry land.[12]More recently, Professor Osborn has advocated the view that they resorted occasionally to the land for egg laying or other purposes, and still more recently the view has been taken by Mr. Riggs and the late Professor Hatcher that they were chiefly terrestrial animals. The writer inclines to the view of Owen and Cope, whose unequalled knowledge of comparative anatomy renders their opinion on this doubtful question especially authoritative.
Fig. 22.: Restoration of Brontosaurus by C.R. Knight, under direction of Professor Osborn.After OsbornFig. 22.—Restoration of Brontosaurus by C.R. Knight, under direction of Professor Osborn.
After Osborn
Fig. 22.—Restoration of Brontosaurus by C.R. Knight, under direction of Professor Osborn.
"The contrast between the massive structure of the limb-bones, ribs and tail, and the light construction of the backbone, neck and skull, suggests that the animal was amphibious, living chiefly in shallow water, where it could wade about on the bottom, feeding upon the abundant vegetation of the coastal swamps and marshes, and pretty much out of reach of the powerful and active Carnivorous Dinosaurs which were its principal enemies. The water would buoy up the massive body and prevent its weight from pressing too heavily on the imperfect joints of the limb and foot bones, which were covered during life with thick cartilage, like the joints of whales, sea-lizards and other aquatic animals. If the full weight of the animal came on these imperfect joints the cartilage would yield and the endsof the bones would grind against each other, thus preventing the limb from moving without tearing the joint to pieces. The massive, solid limb and foot bones weighted the limbs while immersed in water, and served the same purpose as the lead in a diver's shoes, enabling the Brontosaurus to walk about firmly and securely under water. On the other hand, the joints of the neck and back are exceptionally broad, well fitting and covered with a much thinner surface of cartilage. The pressure was thus much better distributed over the joint, and the full weight of the part of the animal above water (reduced as it was by the cellular construction of the bones) might be borne on these joints without the cartilage giving way.
"Looking at the mounted skeleton we may see that if a line be drawn from the hip joint to the shoulder-blade, all the bones below this are massive, all above (including neck and head) are lightly constructed. This line may be taken to indicate the average water-line, so to speak, of this Leviathan of the Shallows. The long neck would enable the animal, however, to wade to a considerable depth, and it might forage for food either in the branches or the tops of trees, or more probably, among the soft succulent water-plants of the bottom. The row of short spoon-shaped stubby teeth around the front of the mouth would serve to bite or pull off soft leaves and water-plants, but the animal evidently could not masticate its food, and must have swallowed it without chewing as do modern reptiles and birds.
"The brain-case occupies only a small part of the back of the skull, so that the brain must have been small even for a reptile, and its organization (as inferred from the form of the brain-case) indicates a very low grade of intelligence. Much larger than the brain proper was the spinal cord, especially in the region of the sacrum, controlling most of the reflex and involuntary actions of the huge organism. Hence we can best regard the Brontosaurus as a great, slow-moving animal automaton, a vast storehouse of organized matter directed chiefly or solely by instinct, and to a very limited degree, if at all, by conscious intelligence. Its huge size and its imperfect organization, compared with the great quadrupeds of today, rendered its movements slow and clumsy; its small and low brain shows that it must have been automatic, instinctive and unintelligent."
Composition of the Brontosaurus Skeleton."The principal specimen, No. 460, is from the Nine Mile Crossing of the Little Medicine Bow River, Wyoming. It consists of the 5th, 6th, and 8th to 13th cervical vertebrae, 1st to 9th dorsal and 3rd to 19th caudal vertebrae, all the ribs, both coracoids, parts of sacrum and ilia, both ischia and pubes, left femur and astragalus, and part of left fibula. The backbone and most of the neck of this specimen were found articulated together in the quarry, the ribs of one side in position, the remainder of the bones scattered aroundthem, and some of the tail bones weathered out on the surface.
"From No. 222, found at Como Bluffs, Wyo., were supplied the right scapula, 10th dorsal vertebra, and right femur and tibia.
"No. 339, from Bone-Cabin Quarry, Wyoming, supplied the 20th to 40th caudal vertebrae, No. 592, from the same locality the metatarsals of the right hind foot; and a few toe bones are supplied from other specimens.
Fig. 23.: Skull of Diplodocus from Bone-Cabin Quarry, north of Medicine Bow, Wyoming.Fig. 23.—Skull ofDiplodocusfrom Bone-Cabin Quarry, north of Medicine Bow, Wyoming.
Fig. 23.—Skull ofDiplodocusfrom Bone-Cabin Quarry, north of Medicine Bow, Wyoming.
"The remainder of the skeleton is modelled in plaster, the scapula, humerus, radius and ulna from the skeleton in the Yale Museum, the rest principally from specimens in our own collections. The modelling of the skull is based partly upon specimens in the Yale Museum, but principally upon the complete skull of Morosaurus shown in another case.
"Mounted by A. Hermann, completed Feb. 10, 1905."