Proterosuchidae

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Proterosuchidae
Temporal range: Late Permian to Early Triassic, 252–247 Ma
Archosaurus rossicus skull.JPG
Restored skull of Archosaurus
Scientific classification e
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[edit]

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 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[edit]

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[edit]

Genera[edit]

Genus[2] Status Age Location Description Images

?Ankistrodon

Nomen dubium Early Triassic India

Archosaurus

Valid Late Permian, Changhsingian Russia and Poland Archosaurus ross1DB.jpg

?Blomosuchus

Nomen dubium Early Triassic, Induan Russia

?Chasmatosuchus

Valid Early Triassic Russia Chasmatosuchus1DB.jpg

Proterosuchus

Valid Early Triassic South Africa and China ProterosuchusDB.jpg

?Vonhuenia

Valid Early Triassic, Induan Russia

Phylogeny[edit]

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.[3][2] 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.[2]



 Prolacertidae




 SAM-PK-591 



 "Ankistrodon indicus" (dubium) 



 "Blomosuchus georgii" (dubium) 



 Tasmaniosaurus triassicus 


 Archosauriformes 
 Chasmatosuchus 

 Chasmatosuchus magnus 



 Chasmatosuchus rossicus 



 Gamosaurus lozovskii 




 Chasmatosuchus vjushkovi 



 Vonhuenia friedrichi 


 Proterosuchidae 

 Archosaurus rossicus 



 Proterosuchus fergusi 




 Proterosuchus alexanderi 




 Proterosuchus goweri 



 Proterosuchus yuani 







 Eorasaurus olsoni



 Kalisuchus rewanensis 



 Fugusuchus hejiapanensis 




 Sarmatosuchus otschevi 




 Cuyosuchus huenei 



 Erythrosuchidae 

 SAM P41754 



 Uralosaurus magnus



 Guchengosuchus shiguaiensis



 other erythrosuchids




 Eucrocopoda









previously assigned to Proterosuchidae

References[edit]

  1. ^ "Archosauria: Archosauriformes". Palaeos. Retrieved 29 October 2014. 
  2. ^ a b c Ezcurra, M.D. (2016). The phylogenetic relationships of basal archosauromorphs, with an emphasis on the systematics of proterosuchian archosauriforms. PeerJ, e1778 [1]
  3. ^ Ezcurra, M.D.; Lecuona, A.; Martinelli, A. (2010). "A new basal archosauriform diapsid from the Lower Triassic of Argentina". Journal of Vertebrate Paleontology. 30 (5): 1433–1450. doi:10.1080/02724634.2010.501446. 

Further reading[edit]

External links[edit]