Reptilian ancestor of the dinosaurs, pterosaurs, and crocodiles.

An informal term for a variety of Permian and Triassic reptiles that had teeth set in individual sockets. Small, bipedal thecodontians are the probable ancestors of dinosaurs.

diapsid Mesozoic (240 mya) tetrapods (dinosaurs that gave rise to birds, crocodilians, lizards, snakes)