Proterosuchidae

Proterosuchidae Temporal range: Late Permian to Early Triassic, 252–247Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Restored skull of Archosaurus
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	Archosauriformes
Family:	†Proterosuchidae Huene, 1914
Genera
see below
Synonyms
Proterosuchinae Huene, 1914 Chasmatosauridae Haughton, 1924 Chasmatosaurinae Haughton, 1924 Pelycosimiidae Abel, 1919

Proterosuchidae is an early, possibly paraphyletic, assemblage of basal archosauriformes whose fossils are known from the Latest Permian and the Early Triassic of Europe, Asia, Africa, Australia and possibly South America. The name comes from Greek πρότερο- ("first") and σοῦχος ("crocodile").

Description

Proterosuchus fergusi from the Early Triassic of South Africa

They were slender, medium-sized (about 1.5 meters long), long-snouted and superficially crocodile-like animals, although they lack the armoured scutes of true crocodiles, and in 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 take center stage as the top carnivore. Within the space of five million years the proterosuchids had evolved into a wide variety of terrestrial and semi-aquatic carnivores.^[1] The proterosuchids represent perhaps the earliest adaptive radiation of the archosaurs. They gave rise to the Erythrosuchidae some time in the Early Triassic.

Classification

Genera

Genus	Status	Age	Location	Description	Images
Ankistrodon	Valid	Early Triassic	India
Archosaurus	Valid	Late Permian, Changhsingian	Russia and Poland
Blomosuchus	Valid	Early Triassic, Induan	Russia
Chasmatosuchus	Valid	Early Triassic	South Africa and China
Exilisuchus	Valid	Early Triassic, Olenekian	Russia
Gamosaurus?	Valid	Early Triassic, Olenekian	Russia
Kalisuchus	Valid	Early Triassic	Australia
Proterosuchus	Valid	Early Triassic	South Africa and China
Tasmaniosaurus	Valid	Early Triassic	Australia
Vonhuenia	Valid	Early Triassic, Induan	Russia

Phylogeny

Some studies consider Proterosuchidae to be a 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 et al. (2010):^[2]

Below is a cladogram from Nesbitt (2011):^[3]

References

Further reading

• Benton, M. J. (2000), Vertebrate Paleontology, 2nd Ed.; (2004) 3rd edition Blackwell Science Ltd
• Carroll, R. L. (1988), Vertebrate Paleontology and Evolution, WH Freeman & Co.

External links

• Proterosuchidae
• Proterosuchidae - list of species (Mikko's Phylogeny Archive)