We have long been acquainted with numerous gigantic terrestrial Saurians, ranging throughout the whole of the Mesozoic formations, such as Iguanodon (characteristic of the Wealden), Megalosaurus (Great Saurian), and Hylæosaurus (Forest Saurian), huge bulky creatures, the last of which, at least, was protected by dermal armour partially produced into prodigious spines; as well as with remarkable forms essentially marine, such as Icthyosaurus (Fish-like Saurian), Plesiosaurus, &c., adapted to an oceanic existence and propelling themselves by means of paddles. The latter, it may be remarked, was furnished with a long slender swan-like neck, which, carried above the surface of the water, would present the appearance of the anterior portion of a serpent.
To the related land forms the collective term Dinosauria (from δεινός “terrible”) has been applied, in signification of the power which their structure and magnitude imply that they possessed; and to the others that of Enaliosauria, as expressive of their adaptation to a maritime existence. Yet, wonderful to relate, those creatures which have for so many years commanded our admiration fade into insignificance in comparison with others which are proved, by the discoveries of the last few years, to have existed abundantly upon, or near to, the American continent during the Cretaceous and Jurassic periods, by which they are surpassed, in point of magnitude, as much as they themselves exceed the mass of the larger Vertebrata.
Take, for example, those referred to by Professor Marsh in the course of an address to the American Association for the Advancement of Science, in 1877, in the following terms:—“The reptiles most characteristic of our American cretaceous strata are the Mososauria, a group with very few representatives in other parts of the world. In our cretaceous seas they rule supreme, as their numbers, size, and carnivorous habits enabled them to easily vanquish all rivals. Some were at least sixty feet in length, and the smallest ten or twelve. In the inland cretaceous sea from which the Rocky Mountains were beginning to emerge, these ancient ‘sea-serpents’ abounded, and many were entombed in its muddy bottom; on one occasion, as I rode through a valley washed out of this old ocean-bed, I saw no less than seven different skeletons of these monsters in sight at once. The Mososauria were essentially swimming lizards with four well-developed paddles, and they had little affinity with modern serpents, to which they have been compared.”
Or, again, notice the specimens of the genus Cidastes, which are also described as veritable sea-serpents of those ancient seas, whose huge bones and almost incredible number of vertebræ show them to have attained a length of nearly two hundred feet. The remains of no less than ten of these monsters were seen by Professor Mudge, while riding through the Mauvaise Terres of Colorado, strewn upon the plains, their whitened bones bleached in the suns of centuries, and their gaping jaws armed with ferocious teeth, telling a wonderful tale of their power when alive.
The same deposits have been equally fertile in the remains of terrestrial animals of gigantic size. The Titanosaurus montanus, believed to have been herbivorous, is estimated to have reached fifty or sixty feet in length; while other Dinosaurians of still more gigantic proportions, from the Jurassic beds of the Rocky Mountains, have been described by Professor Marsh. Among the discovered remains of Atlantosaurus immanis is a femur over six feet in length, and it is estimated from a comparison of this specimen with the same bone in living reptiles that this species, if similar in proportions to the crocodile, would have been over one hundred feet in length.
But even yet the limit has not been reached, and we hear of the discovery of the remains of another form, of such Titanic proportions as to possess a thigh-bone over twelve feet in length.
Fig. 5.—Monster bones of extinct gigantic Saurians
from Colorado, showing relative proportions
to corresponding bone in the Crocodile (A).
(From the “Scientific American.”)
From these considerations it is evident that, on account of the dimensions usually assigned to them, no discredit can be attached to the existence of the fabulous monsters of which we shall speak hereafter; for these, in the various myths, rarely or never equal in size creatures which science shows to have existed in a comparatively recent geological age, while the quaintest conception could hardly equal the reality of yet another of the American Dinosaurs, Stegosaurus, which appears to have been herbivorous, and more or less aquatic in habit, adapted for sitting upon its hinder extremities, and protected by bony plate and numerous spines. It reached thirty feet in length. Professor Marsh considers that this, when alive, must have presented the strangest appearance of all the Dinosaurs yet discovered.
The affinities of birds and reptiles have been so clearly demonstrated of late years, as to cause Professor Huxley and many other comparative anatomists to bridge over the wide gap which was formerly considered to divide the two classes, and to bracket them together in one class, to which the name Sauropsidæ has been given.[35]