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An antorbital opening primitively present but lost in many ancient and all modern forms. Mandible with an external vacuity posteriorly. Nine cervical vertebrae, twenty-three or twenty-four presacrals. No sclerotic plates in orbits. Body with dermal bones. Feet partly webbed, clawed, not paddle-like.

Until within recent years, and still by some authors, the Eusuchia comprised only those crocodilians with procoelous vertebrae, amphicoelian forms comprised in the suborder Mesosuchia. It is now known that the change in the form of the vertebrae was a relatively unimportant one and may have occurred in different lines of descent.

. Vertebrae platycoelous. Internal nares large, situated at posterior end of palatines. Face very long and slender. An antorbital opening sometimes present. Postorbital bar not modified. Upper temporal opening large. A nearly complete dermal armor. Front feet much smaller than hind. From two to ten feet in length.

Jurassic. Pelagosaurus Bronn, Teleosaurus Geoffroy, Teleidosaurus Deslongchamps, Suchodus Lydekker, Aeolodon Meyer, Crocodilemus Jourdan, Gnathosaurus Münster, Europe. Steneosaurus Geoffroy, Europe, Madagascar.

Cretaceous. ? Teleorhinus Osborn, Wyoming.

. Vertebrae platycoelous. Internal nares opening in palatines and pterygoids. Face long; the nasals reach to the premaxillae. Upper temporal opening smaller than orbits. Postorbital bar modified. Front legs larger than in the Teleosauridae. Dorsal and ventral armor present.

Upper Jura and Lowermost Cretaceous. Pholidosaurus Meyer (Macrorhynchus), Pterosuchus Owen, Europe.

. Vertebrae platycoelous. Posterior nares not reaching pterygoids. Head short, broad. Upper temporal openings much smaller than orbits. Dermal armor composed of two rows of quadrilateral plates, probably extending on tail. Probably no ventral scutes. Tail long. Small reptiles from eight to sixteen inches in length.