"This group, which includes at least three well-established genera of Saurians, is characterized by a large sacrum, composed of five anchylosed vertebræ of unusual construction; by the height, breadth, and outward sculpture of the neural arch of the dorsal vertebræ; by the two-fold articulation of the ribs to the vertebra:, viz. at the anterior part of the spine by a head and tubercle, and along the rest of the trunk by a tubercle attached to the transverse process only; by broad, and sometimes complicated, coracoids, and long and slender clavicles; whereby Crocodilian characters of the vertebral column are combined with a Lacertian type of the pectoral arch. The dental organs also exhibit the same transitional or annectent characters, in a greater or lesser degree. The bones of the extremities are of large proportional size for Saurians; they are provided with large medullary cavities, and with well developed and unusual processes, and are terminated by metacarpal, metatarsal, and phalangeal bones, which, with the exception of the ungual phalanges, more or less resemble those of the heavy pachydermal Mammals, and attest, with the hollow long-bones, the terrestrial habits of the species.
"The combinations of such characters, some, as the sacral ones, altogether peculiar among Reptiles, others borrowed, as it were, from groups now distinct from each other, and all manifested by creatures far surpassing in size the largest of existing reptiles, will, it is presumed, be deemed sufficient ground for establishing a distinct tribe or sub-order of Saurian Reptiles, for which I would propose the name of Dinosauria.
"Of this tribe the principal and best established genera are the Megalosaurus, the Hylæosaurus, and the Iguanodon; the gigantic Crocodile-lizards of the dry land; the peculiarities of the osteological structure of which distinguish them as clearly from the modern terrestrial and amphibious Sauria, as the opposite modifications for an aquatic life characterize the extinct Enaliosauria, or Marine Lizards."[626]
[626] Brit. Assoc. Rep. 1841, p. 103.
The elaborate investigation of the fossil remains of these stupendous beings, and the luminous exposition of their organization and physiological relations, embodied in the report to which the above extract is introductory, are among the most important contributions to Palæontology, and afford a striking example of the successful application of profound anatomical knowledge to the elucidation of the most marvellous epoch in the earth’s physical history, the Age of Reptiles.
From the great size of the bones of these reptiles, their remains have excited the curiosity even of the common observer; and although an exaggerated idea has been generally entertained of the magnitude of the original animals, yet, even when reduced to their natural proportions by the rigorous formula of the anatomist, applied to the accumulated relics which years of laborious research have exhumed from their rocky sepulchres and deposited in our museums, their dimensions are sufficiently stupendous to satisfy the most enthusiastic lover of the marvellous.
Let the reader visit the British Museum,[627] and after examining the largest thigh-bone of the Iguanodon, repair to the zoological gallery, and inspect the recent Crocodilian reptiles, some twenty-five or thirty feet in length; and observe that the fossil bone equals, if not surpasses, in size, the entire thigh of the largest of existing reptiles; then let him imagine this bone clothed with proportionate muscles and integuments, and reflect upon the enormous trunk which such limbs must have been destined to move and to sustain—and he will obtain a just notion of the appalling magnitude of the lizards which inhabited the country of the Iguanodon.
[627] See Fossils of the British Museum, p. 227.
The general characters of the extinct reptiles comprised in the order Deinosauria[628] must be known to the intelligent reader, from the various popular notices which have from time to time appeared; and their names have become as familiar as household words. I shall here restrict myself to a few general remarks on the form and structure of the teeth, and of some of the more important bones of the best known species of these great reptiles.[629]
[628] In the new edition of Pictet’s Paléontologie (now in course of publication), two 4to. plates (xxiii. and xxiv.) are devoted to the illustration of the remains of these colossal reptiles.