Temporal range: Latest Permian to Latest Early Triassic, 252–247 Ma
Possible Middle Triassic records
Restored skull of Archosaurus
Scientific classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Archosauromorpha
Clade: Archosauriformes
Family: Proterosuchidae
Huene, 1914
  • Proterosuchinae Huene, 1914
  • Chasmatosauridae Haughton, 1924
  • Chasmatosaurinae Haughton, 1924
  • Pelycosimiidae Abel, 1919

Proterosuchidae is an early family of basal archosauriforms whose fossils are known from the Late Permian and the Early Triassic. The highest diversity of genera is known from European Russia, but fossils are also known from South Africa, India, China, Australia, Brazil and possibly Argentina. The name comes from Greek πρότερο- ("first") and σοῦχος ("crocodile").


Proterosuchus fergusi from the Early Triassic of South Africa

They were slender, medium-sized (about 1.5 m (4 ft 11 in) long, largest specimens reached 3.5–4 m (11–13 ft)), long-snouted and superficially crocodile-like animals, although they lacked the armoured scutes of true crocodiles, and their skeletal features are much more primitive. The limbs are short and indicate a sprawling posture, like contemporary lizards but unlike most later archosaurs.

Their most characteristic feature is a distinct down-turning of the premaxilla (the front of the upper jaw, which overhangs the lower jaw).

Evolutionary history

The terminal Permian catastrophe, which killed off 95% of all types of life, cleared the world of all large therapsids and allowed the proterosuchids to become the top predators. Within the space of five million years the proterosuchids had evolved to fill a wide variety of terrestrial and semi-aquatic niches. The proterosuchids represent perhaps the earliest adaptive radiation of the archosaurs. They gave rise to the Erythrosuchidae some time in the Early Triassic.[citation needed]

A 2023 study recovered a majority of proterosuchids outside of Proterosuchus and Sarmatosuchus as belonging to a distinct subfamily, the Chasmatosuchinae. Chasmatosuchinae contains many Triassic proterosuchids in addition to the only Permian proterosuchid, Archosaurus; this would suggest that an initial taxonomic diversification of the Proterosuchidae (including an initial taxonomic divergence between Proterosuchus and chasmatosuchines) had already occurred in the Permian.



Recent studies consider Proterosuchidae to be at least a partially paraphyletic grouping, meaning that it does not form a true clade with a single common ancestor and proterosuchids as its only descendants. Instead, they are a chain of successively basal archosauriforms. Below is a cladogram from Ezcurra (2016), that reexamined all historical members of the "Proterosuchia" (a polyphyletic historical group including proterosuchids and erythrosuchids). The placement of fragmentary taxa that had to be removed to increase tree resolution are indicated by dashed lines (in the most derived position that they can be confidently assigned to). Taxa that are nomina dubia are indicated by the note "dubium". Bold terminal taxa are collapsed. Ezcurra (2016) recovered a monophyletic Proterosuchidae containing only Archosaurus and the species of Proterosuchus, however some species (e.g. Chasmatosuchus spp, Vonhuenia friedrichi) are too fragmentary to resolve whether they also fall into Proterosuchidae. Tasmaniosaurus, Fugusuchus, Sarmatosuchus, Cuyosuchus and the "Long Reef proterosuchid" (SAM P41754) on the other hand were recovered confidently outside of Proterosuchidae.

previously assigned to Proterosuchidae

The following phylogeny for the Proterosuchidae sensu stricto was recovered by Ezcurra et al (2023):



Genus Status Age Location Description Images


nomen dubium Early Triassic India


Valid Late Permian, Changhsingian Russia


nomen dubium Early Triassic, Induan Russia


Valid Early Triassic Russia
Gamosaurus Valid Early Triassic Russia
Jaikosuchus Valid Early Triassic Russia
Koilamasuchus Disputed Middle - Late Triassic Argentina


Valid Early Triassic South Africa
Samsarasuchus Valid Early Triassic India
Sarmatosuchus Disputed Early Triassic Russia
Tsylmosuchus Valid Early Triassic Russia


Valid Early Triassic, Induan Russia

This page was last updated at 2024-04-17 15:47 UTC. Update now. View original page.

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