Proterosuchia: the origin and early history of Archosauriformes

EZCURRA, MARTÍN D; BUTLER, RICHARD J.; GOWER, DAVID J.

Anatomy, Phylogeny and Palaeobiology of Basal Archosaurs

The Geological Society of London

Año: 2013; p. 9 - 33

The earliest history of Archosauriformes is mainlyrepresented by members of Proterosuchidae and Erythrosuchidae, which are knownworldwide from latest Permian to Middle Triassic beds. These two groups werehistorically combined within ?Proterosuchia?, with approximately 30 nominalspecies. Two morphotypes have been recognized among proterosuchians:proterosuchids with a generally more sprawling gait and elongated and lowskulls with an overhanging premaxilla, and the more heavily builterythrosuchids, with a probably less sprawling gait and large, presumablyhypercarnivorous, skulls. The systematics of ?Proterosuchia? was relativelychaotic throughout most of the twentieth century, but currently there existsconsensus regarding the non-monophyly of proterosuchians and their phylogeneticposition outside all other archosauriforms. In contrast, the delimitation andtaxonomic content of Proterosuchidae and Erythrosuchidae remain unstable. Fewstudies of proterosuchian palaeobiology have been carried out. Current lines ofevidence favour a predominantly terrestrial lifestyle for proterosuchians. Limbbone histology indicates rapid continuous growth rates in Proterosuchus andErythrosuchus before reaching sexual maturity. A better knowledge ofproterosuchian anatomy, systematics, evolution and ecology is important foradvancing understanding of the origin and early radiation of Archosauriformesand the patterns of biotic recovery following the Permo-Triassic massextinction event. There remains much research to be carried out inproterosuchian palaeobiology.