opening and dorsal anterior nares, snout not greatly produced. Teeth thecodont. Distinguished from the Phytosauria especially by the absence of the upper temporal opening, which may have been secondarily lost as in the caimans. Von Huene refers Desmatosuchus to the Phytosauria.
Triassic. Desmatosuchus Case, Texas.]
16. ORDER CROCODILIA[1]
[Loricata]
Internal nares carried far back in the mouth by the union of the maxillae and palatines, and in the later forms the pterygoids also. Premaxillae never much elongate, the external nares terminal. Acetabulum formed by ilium and ischium only, the so-called pubes (? prepubes) excluded and not meeting in a median symphysis. Phalanges of fourth and fifth digits reduced; calcaneum elongate. Two sacral vertebrae.
The Crocodilia are at once distinguished from all other reptiles by the structure of the palate and pelvis. There is not a very great diversity of structure among the known forms. All are lizard-like in form, with a long, flattened tail, very predaceous, with conical thecodont teeth, and more or less water-loving in habit. In size they vary from less than one foot to about fifty feet in length. The vertebrae were platycoelous in all till about the beginning of the Lower Cretaceous; procoelous in all since the early part of the Eocene. Some have a relatively broad skull; others a more or less elongated face, sometimes very slender, as in the ancient teleosaurs and the modern gavials. In such forms the nasals do not reach the external nares, and the splenials meet in a symphysis. The upper temporal openings in the modern forms are smaller, very small in the broad-faced types. In the early types the arch between the orbit and lateral temporal opening was covered immediately by the skin; since Wealden times the bar is more cylindrical and more deeply placed. The amphibious crocodiles have a strong dermal, osseous armor along the back and tail, sometimes also on the under side. Both the carpus and tarsus are peculiarly modified, suggesting, v. Huene thinks, a primitive, more upright-walking gait.
- ↑ [For recent morphological and taxonomic treatment of the Crocodilia, see numerous papers by C. C. Mook, 1921–, Bulletin, Amer. Mus. Nat. Hist.—Ed.]
