Page:Notice of New Dinosaurian Reptiles from the Jurassic formation.pdf/1

. LIII.—Notice of New Dinosaurian Reptiles from the Jurassic formation; by Professor O. C..

gigantic, , described by the writer in the July number of this Journal, proves to belong to a lower horizon than at first supposed, and is really from the. Additional remains of the type specimen, moreover, throw considerable light on the structure of this largest of land animals, and indicate that it is the representative of a distinct, which may be called.

In the type, , one of the most important characters is the of the vertebræ, as mentioned in the original description. Another noteworthy feature is the absence on the femur of a third. The shaft of the bone is somewhat thickened at the point where this process should be, but the trochanter is wanting. The size of the original specimen of A. montanus may be estimated from the femur, which was about seven feet in length. If the animal had the proportions of a Crocodile, it was at least eighty feet long.

Another gigantic Dinosaur, allied to the above, and of scarcely less interest, is represented in the Yale Museum by a nearly complete skeleton in excellent preservation. It is from the Jurassic beds in the Eastern foot hills of the Rocky Mountains, but from a somewhat lower horizon than the type of Atlantosaurus.

The vertebræ are strongly, and are rendered comparatively light by large pneumatic cavities in the centra. The dorsals have similar characters. The  have the  faces very nearly flat, and. The vertebræ are more solid, and have their transverse processes nearer the middle of the centra than in Atlantosaurus. The anterior caudals are biconcave, and their