Prehistoric reptile taxonomy

__NOTOC__ thumb|right|A euryapsid skull. Euryapsida is a polyphyletic (unnatural, as the various members are not closely related) group of sauropsids that are distinguished by a single temporal fenestra, an opening behind the orbit, under which the post-orbital and squamosal bones articulate. They are different from Synapsida, which also have a single opening behind the orbit, by the placement of the fenestra. In synapsids, this opening is below the articulation of the post-orbital and squamosal bones. It is now commonly believed that euryapsids (particularly sauropterygians) are in fact diaps

thumb|right|Rutiodon, one of the aquatic and superficially crocodile-like [[phytosaurs]] Thecodontia (meaning 'socket-teeth'), now considered an obsolete taxonomic grouping, was formerly used to describe a diverse "order" of early archosaurian reptiles that first appeared in the latest Permian period and flourished until the end of the Triassic period. All of them were built somewhat like crocodiles but with shorter skulls, more erect pose and usually somewhat lighter. The group includes the ancestors of dinosaurs, pterosaurs, and crocodilians, as well as a number of extinct forms that did not

thumb|right|Fossil of Labidosaurus|Labidosaurus hamatus Captorhinida (older name: Cotylosauria) is a doubly paraphyletic grouping of early reptiles. Robert L. Carroll (1988) ranked it as an order in the subclass Anapsida, composed of the following suborders:

Eosuchia is a proposed order of extinct diapsid reptiles comprising taxa from the Permian and Triassic. Eosuchia was initially defined to include all "thecodontian" reptiles which did not have an antorbital fenestra but did retain tabulars, postparietals, and a large pineal foramen (Broom, 1914). Broom coined the term as a new suborder for Youngina.