[5] Archosauriforms are a branch of archosauromorphs which originated in the Late Permian (roughly 252 million years ago) and persist to the present day as the two surviving archosaur groups: crocodilians and birds.

These include serrated teeth set in deep sockets, a more active metabolism, and an antorbital fenestra (a hole in the skull in front of the eyes).

Early archosauriforms, informally termed "proterosuchians", were superficially crocodile-like animals with sprawling gaits, carnivorous habits, and long hooked snouts.

The next major archosauriform group was Erythrosuchidae, a family of apex predators with massive heads, the largest carnivorous reptiles up to that time.

He defined the clade all taxa more closely related to Euparkeria capensis, Proterochampa barrionuevoi, Doswellia kaltenbachi, Parasuchus hislopi, Passer domesticus (the house sparrow), or Crocodylus niloticus (the Nile crocodile) than to Proterosuchus fergusi or Erythrosuchus africanus.

[7] The same method also supports the existence of high resting metabolical rates similar to those of living endotherms (mammals and birds) in the Prolacerta-Archosauriformes clade that were retained by most subgroups, though decreased in Proterosuchus, Phytosauria and Crocodilia.

Sexual maturity in those Triassic taxa was probably reached quickly, providing advantage in a habitat with unpredictable variation from heavy rainfall to drought and high mortality.

Living crocodilians are ambush predators adapted to a semi-aquatic lifestyle that benefits from ectothermy due to the lower oxygen intake that allows longer diving time.

[13] The similarities between pterosaur, ornithischian and coelurosaurian integument suggest a common origin of thermal insulation (feathers) in ornithodirans at least 250 million years ago.