Biology:Proterochampsidae

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Short description: Extinct family of reptiles

Proterochampsids
Temporal range: Middle - Late Triassic, 242–205.6 Ma
Pseudochampsa.png
Nearly complete skeleton of Pseudochampsa
Scientific classification e
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Archosauromorpha
Clade: Archosauriformes
Clade: Proterochampsia
Family: Proterochampsidae
Romer, 1966
Genera
Synonyms
  • Rhadinosuchidae Hoffstetter, 1955

Proterochampsidae is a family of proterochampsian archosauriforms. Proterochampsids may have filled an ecological niche similar to modern crocodiles, and had a general crocodile-like appearance. They lived in what is now South America in the Middle and Late Triassic.

Description

Proterochampsids have long, crocodile-like skulls. The posterior portion of the skull is wide while the snout is very narrow. Most proterochampsids also have downturned snouts. Like many early archosauriforms, they also have dermal armour.

Proterochampsids have small holes called dorsal fenestrae at the top of their skulls. Unlike other early archosauromorphs, they do not have a parietal foramin, which in many reptiles holds a parietal eye. The postorbital bones behind the eye sockets have thick, jagged crests. As another diagnostic feature of the group, the holes that allow the passage of the internal carotid artery through the braincase open at the sides of a bony projection called the basipterygoid process. Proterochampsids are primitive in that they have simple plate-like pelvises, but they lack small bones in the vertebra called intercentra that are common in earlier reptiles.

As in most archosaurs, distinguishing features can be seen in the shape of the ankle bones. A projection on the calcaneum bone called the calcaneal tuber is narrow and positioned downward relative to other lateral projections on the bone. The calcaneum also has a facet that attaches to both the fibula bone of the leg and another tarsal, or ankle bone. A hemicylindrical facet on the calcaneum attaches to another bone in the ankle called the astragalus. The astragalus has facets that attach to the tibia and fibula that are adjacent to each other.

Classification

Proterochampsidae was named in 1966 by A.S. Romer in his book Vertebrate Paleontology, 3rd edition. Members such as Proterochampsa and Cerritosaurus had been known for several decades prior to the family's creation. Proterochampsids were originally thought to be close relatives of crocodilians based on their similar appearance. In the following years, proterochampsids were frequently associated with Proterosuchia, another group of long-snouted Triassic archosauriforms. As phylogenetic studies became more common in the 1980s and 1990s, proterochampsids were found to be a distinct group closely related to true archosaurs. Recent studies have placed Proterochampsidae as either the sister taxon of Archosauria (the closest relatives of archosaurs), or the sister taxon of Archosauria and Euparkeria.[1] In a 2011 study, the unusual Late Triassic archosauriform Doswellia has been placed as the closest relative of proterochampsids. Because doswelliids are more closely related to proterochampsids than to any other archosauriform, the two groups form their own clade.[2]

Seven species have been assigned to Proterochampsidae: Cerritosaurus binsfeldi, Chanaresuchus bonapartei, Gualosuchus reigi, Rhadinosuchus gracilis, Tropidosuchus romeri, Proterochampsa barrionuevoi, and Proterochampsa nodosa. P. nodosa was assigned to its own genus Barberenachampsa in 2000, but it is generally still considered to be a species of Proterochampsa.[3] Modern studies place Proterochampsids in a larger group called Proterochampsia. Under the classification of Kischlat and Schultz (1999), Cerritosaurus, Proterochampsa, and Tropidosuchus are basal forms, while Chanaresuchus, Gualosuchus, and Rhadinosuchus form the family Rhadinosuchidae.[4] However, more recent studies reduce Rhadinosuchidae to a subfamily level as Rhadinosuchinae to be placed within Proterochampsidae and include advanced proterochampsid, e.g. Chanaresuchus and Rhadinosuchus.[5][6][7] Below is a cladogram following the phylogenetic analysis of Ezcurra (2016) that recovered Doswelliidae as the sister taxon of Proterochampsidae (within Proterochampsia). Proterochampsia was found to be the sister taxon of Archosauria, whose living representatives consist of birds and crocodilians.[7]

 Eucrocopoda 

Dorosuchus neoetus

Euparkeria capensis (Euparkeriidae)

Dongusuchus efremovi

Yarasuchus deccanensis

 Archosauria 

Avemetatarsalia

 Pseudosuchia 

Phytosauria

The rest of Pseudosuchia (incl. Koilamasuchus)

 Proterochampsia 
 Doswelliidae 

Vancleavea campi

Archeopelta arborensis

Tarjadia ruthae

Doswellia kaltenbachi

Jaxtasuchus salomoni

 Proterochampsidae 

Proterochampsa barrionuevoi

Proterochampsa nodosa

Cerritosaurus binsfeldi

Tropidosuchus romeri

 Rhadinosuchinae 

Pseudochampsa ischigualastensis

Gualosuchus reigi

Chanaresuchus bonapartei

Rhadinosuchus gracilis

Genera

Genus Authority Age Location Unit Notes Images

Cerritosaurus

Price (1946) Ladinian

 Brazil

Santa Maria Formation

Cerritosaurus.jpg

Chanaresuchus

Romer (1971) Ladinian

 Argentina

Chañares Formation

Chanaresuchus.jpg

Gualosuchus

Romer (1971) Ladinian

 Argentina

Chañares Formation

Gualosuchus.jpg

Kuruxuchampsa[8]

Paes-Neto et al. (2023) Carnian

 Brazil

Santa Maria Formation

Kuruxuchampsa.jpg

Pinheirochampsa[8]

Paes-Neto et al. (2023) Ladinian–Carnian

 Brazil

Santa Maria Formation

Pinheirochampsa.jpg

Proterochampsa

Reig (1959) Norian

 Argentina

Ischigualasto Formation

Includes Barberenachampsa as a subjective junior synonym according to most authors.
Proterochampsa.jpg

Pseudochampsa

Trotteyn & Ezcurra (2014) Norian

 Argentina

Ischigualasto Formation

Pseudochampsa life restoration white background.jpg

Rhadinosuchus

Huene (1942)

Ladinian

 Brazil

Santa Maria Formation

Rhadinosuchus.jpg

Stenoscelida[9]

Müller et al. (2022) Carnian/Norian

 Brazil

Santa Maria Formation
Stenoscelida.jpg

Tropidosuchus

Arcucci (1990)

Ladinian

 Argentina

Chañares Formation

Tropidosuchus.jpg

Sources

  • A. S. Romer. 1966. Vertebrate Paleontology, 3rd edition. University of Chicago Press, Chicago 1-468
  1. Nesbitt, S.J. (2011). "The early evolution of archosaurs: relationships and the origin of major clades". Bulletin of the American Museum of Natural History 352: 1–292. doi:10.1206/352.1. https://zenodo.org/record/5405335. 
  2. Julia B. Desojo; Martin D. Ezcurra; Cesar L. Schultz (2011). "An unusual new archosauriform from the Middle–Late Triassic of southern Brazil and the monophyly of Doswelliidae". Zoological Journal of the Linnean Society 161 (4): 839–871. doi:10.1111/j.1096-3642.2010.00655.x. 
  3. Langer, M.C.; Ribeiro, A.M.; Schultz, C.L.; Ferigolo, J. (2007). "The continental tetrapod-bearing Triassic of South Brazil". The Global Triassic. New Mexico Museum of Natural History and Science Bulletin. 41. pp. 201–218. http://sites.ffclrp.usp.br/paleo/pdf/Langer_et_al_2007b.pdf. 
  4. Kischlat, E.; Schultz, C.L. (1999). "Phylogenetic analysis of Proterochampsia (Thecodontia: Archosauriformes)". Ameghiniana 36 (4): 13R. https://books.google.com/books?id=FbB7FFaW8_8C&q=Phylogenetic+analysis+of+Proterochampsia+%28Thecodontia%3A+Archosauriformes%29&pg=PT14. 
  5. Trotteyn, M. A. J.; Haro, J. A. (2012). "The braincase of Chanaresuchus ischigualastensis (Archosauriformes) from the Late Triassic of Argentina". Journal of Vertebrate Paleontology 32 (4): 867. doi:10.1080/02724634.2012.670178. 
  6. María Jimena Trotteyn; Martín D. Ezcurra (2014). "Osteology of Pseudochampsa ischigualastensis gen. et comb. nov. (Archosauriformes: Proterochampsidae) from the Early Late Triassic Ischigualasto Formation of Northwestern Argentina". PLOS ONE 9 (11): e111388. doi:10.1371/journal.pone.0111388. PMID 25426846. Bibcode2014PLoSO...9k1388T. 
  7. 7.0 7.1 Ezcurra, MD (2016). "The phylogenetic relationships of basal archosauromorphs, with an emphasis on the systematics of proterosuchian archosauriforms". PeerJ 4: e1778. doi:10.7717/peerj.1778. PMID 27162705. 
  8. 8.0 8.1 Paes-Neto, V. T.; Lacerda, M. B.; Ezcurra, M. D.; Raugust, T.; Trotteyn, M. J.; Soares, M. B.; Schultz, C. L.; Pretto, F. A. et al. (2023). "New rhadinosuchine proterochampsids from the late Middle-early Late Triassic of southern Brazil enhance the diversity of archosauriforms". The Anatomical Record. doi:10.1002/ar.25294. PMID 37589539. 
  9. Müller, R. T.; Garcia, M. S.; Fonseca, A. de O. (2022). "A new proterochampsid (Archosauriformes: Proterochampsia) from the Late Triassic of southern Brazil and the emergence of archosaurian hind limb traits". Journal of Systematic Palaeontology 20 (1): 2128913. doi:10.1080/14772019.2022.2128913. 

Wikidata ☰ Q599138 entry