Proterochampsia

left|thumb|Life restoration of Proterochampsa barrionuevoi Proterochampsia is a clade of early archosauriform reptiles from the Triassic period. It includes the Proterochampsidae (e.g. Proterochampsa, Chanaresuchus and Tropidosuchus) and probably also the Doswelliidae. Nesbitt (2011) defines Proterochampsia as a stem-based taxon that includes Proterochampsa barrionuevoi and all forms more closely related to it than Euparkeria capensis, Erythrosuchus africanus, Passer domesticus (the House Sparrow), or Crocodylus niloticus (the Nile crocodile). Therefore, the inclusion of Doswelliidae in it is dependent upon whether Doswellia and Proterochampsa form a monophyletic group to the exclusion of Archosauria and other related groups.

==Description== Nesbitt (2011) found that Proterochampsians share several distinguishing characteristics, or synapomorphies. A prominent ridge runs along the length of the jugal, a bone below the eye. Another ridge is present on the quadratojugal, a bone positioned toward the back of the skull behind the jugal. There is also a depression on the squamosal bone of the skull roof. The second metatarsal of the foot is wider than the other metatarsals. Proterochampsians lack a fifth digit on the foot; the fifth metatarsal is reduced to a small pointed bone. However, Nesbitt (2011) only considered Proterochampsia to include Proterochampsidae. Ezcurra (2016), who recovered a clade formed by Proterochampsidae and Doswelliidae, defined Proterochampsia by up-facing nostrils, maxilla-to-prefrontal contact, the tooth bearing part of the upper jaw being curved downwards, neck and front back vertebrae lacking a postzygodiapophyseal lamina, tibia with straight cnemial crest, fifth metatarsal that is not hook-shaped in its inner end, well developed foot phalanges on the fifth digit but with a poorly developed first phalanx, among other traits.