18 WATER REPTILES OF THE PAST AND PRESENT 



Order PARASUCHIA 



Subaquatic reptiles, with two temporal vacuities; an antorbital vacuity; 

 no false palate; pubis entering acetabulum; ribs double-headed, diapo- 

 physial. 



Suborder Phytosauria Upper Trias, cosmopolitan. 

 Pelycosimia Trias, Africa. 

 Pseudosuchia Trias, Europe, North America. 



Order CROCODILIA 



Two temporal vacuities; teeth thecodont; a false palate; pubis excluded 

 from acetabulum; single coracoid; ribs double-headed, diapophysial ; 

 subaquatic or aquatic. 



Suborder Eusuchia Jurassic to recent. 



Thalattosuchia Upper Jurassic, Europe. 



Order DINOSAURIA 



Ambulatory reptiles, with two temporal vacuities; no false palate; pubis 

 entering acetabulum; ribs double-headed, diapophysial. 



Suborder Theropoda Upper Trias to close of Cretaceous, cosmopolitan. 

 Orthopoda Close of Trias to close of Cretaceous, cosmopolitan. 

 Sauropoda Upper Jurassic, Lower Cretaceous, cosmopolitan. 



Order PTEROSAURIA 



Volant reptiles; fourth finger greatly elongated to support patagium; 

 neck vertebrae elongated; bones hollow; ribs double-headed, diapo- 

 physial; a single coracoid; no clavicles or interclavicle; two temporal 

 vacuities. 



Suborder Pterodermata Jurassic, Europe. 



Pterodactyloidea Upper Jurassic to Upper Cretaceous, Europe, 

 North America. 



