Part 3 (1/2)

But the giant herbivorous dinosaurs, well armed or well defended though they were, had not the intelligence to use those weapons effectively under all circ.u.mstances. Thus they might be successfully attacked, at least sometimes, by the powerful although slow moving Megalosaurians.

The suggestion has also been made that these giant carnivores 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 the _Tyrannosaurus_ but smaller, about equal in size to _Allosaurus_, was the _Albertosaurus_ of 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 as _Laelaps_ (=_Dryptosaurus_).[10]

_Ornitholestes._ In contrast with the _Allosaurus_ and _Tyrannosaurus_ this 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. The _Anchisaurus_, _Podokesaurus_ and other genera of the Tria.s.sic Period have left innumerable tracks upon the sandy shales of the Newark formation, but only two or three skeletons are known. A cast of one of them is exhibited here. The original is preserved in the Yale Museum. In the succeeding Jura.s.sic Period we have the _Compsognathus_, smallest of known dinosaurs, and this _Ornitholestes_ some six feet long. A cast of the _Compsognathus_ skeleton is shown, the original found in the lithographic limestone of Solenhofen is preserved in the Munich Museum. The _Ornitholestes_ is 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 of _Ornithomimus_ at the entrance to the Dinosaur Hall finely ill.u.s.trates 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 the end 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 of _Ornitholestes_, _Compsognathus_ and _Anchisaurus_ by Charles Knight.

[Ill.u.s.tration: Fig. 17.--Skeleton of _Ornitholestes_ a small carnivorous dinosaur of the Jura.s.sic period. American Museum No.

619.]

[Ill.u.s.tration: Fig. 18.--Restoration of _Ornitholestes_, by C.R.

Knight under direction of Professor Osborn. _After 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 relations.h.i.+ps have not yet been thoroughly investigated.

[Ill.u.s.tration: Fig. 19.--MOUNTED SKELETON OF BRONTOSAURUS IN THE AMERICAN MUSEUM.]

FOOTNOTES:

[Footnote 4: This is still doubtful in _Tyrannosaurus_. A number of very curious plates were found with one specimen in a quarry. B.

Brown, 1913.]

[Footnote 5: Quite recently a series of more or less complete skeletons have been secured from the upper Tria.s.sic (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. _Anchisaurus_ certainly belongs to it.]

[Footnote 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.]

[Footnote 7: Allosaurus, a carnivorous Dinosaur, and its Prey. By W.D.

Matthew. Am. Mus. Nat. Hist. Jour. Vol. viii, pp. 3-5, pl. 1.]

[Footnote 8: The cost of preparation is now defrayed by the Museum.]

[Footnote 9: Tyrannosaurus, Restoration and Model of the Skeleton. By Henry Fairfield Osborn. Bull. Amer. Mus. Nat. Hist., 1913, vol. x.x.xii, art. iv, pp. 91-92.]

[Footnote 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.]

CHAPTER V.

THE AMPHIBIOUS DINOSAURS, BRONTOSAURUS, DIPLODOCUS, ETC.

SUB-ORDER OPISTHOCOELIA (CETIOSAURIA OR SAUROPODA).

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 ma.s.sive 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 Jura.s.sic and Comanchic (”Lower Cretaceous”) and belong to the older of the two princ.i.p.al 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.