Proterosuchidae

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Proterosuchids
Temporal range: Latest Permian to Latest 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 family of basal archosauriforms 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 m (4 ft 11 in) long, largest specimens reached 3.5–4 m (11–13 ft)[1]), 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 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.[2] 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]

Classification[edit]

Genera[edit]

Genus[3] Status Age Location Description Images

Ankistrodon

Valid Early Triassic India

Archosaurus

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

Blomosuchus

Valid 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.[4][3] 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.[3]

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. ^ Julia Brenda Desojo, Randall B. Irmis, Sterling J. Nesbitt (2013). Anatomy, Phylogeny and Palaeobiology of Early Archosaurs and Their Kin. Geological Society. p. 20. ISBN 9781862393615. Retrieved 14 September 2022.{{cite book}}: CS1 maint: multiple names: authors list (link)
  2. ^ "Archosauria: Archosauriformes". Palaeos. Retrieved 29 October 2014.
  3. ^ 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]
  4. ^ 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]