Crurotarsi
Crurotarsans | |
---|---|
Life restoration of Protome batalaria, a phytosaur
| |
Life restoration of pseudosuchian archosaur
| |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Reptilia |
Clade: | Archosauromorpha |
Clade: | Archosauriformes |
Clade: | Eucrocopoda
|
Clade: | Crurotarsi Sereno & Arcucci, 1990 |
Subgroups | |
|
Crurotarsi is a clade of archosauriform reptiles that includes crocodilians and stem-crocodilians and possibly bird-line archosaurs too if the extinct, crocodile-like phytosaurs are more distantly related to crocodiles than traditionally thought.[1] Prior to 2011, the group had invariably included only archosaurs closer to crocodilians than to birds and other dinosaurs. An equivalent term for the crocodilian side of the archosaur family tree is Pseudosuchia. This traditional definition of Crurotarsi assumed that phytosaurs were crown-group archosaurs and more closely related to crocodilians than to birds. However, a 2011 study argued that the phytosaur lineage evolved prior to the split between birds and crocodilians. This would mean that phytosaurs were not true archosaurs, and therefore could not be considered representatives of croc-line archosaurs.[1]
The name Crurotarsi is derived from the Latin word
Taxonomic history
The name Crurotarsi was erected as a
Phylogeny
Paul Sereno and A. B. Arcucci named Crurotarsi in 1990, defining it as "
Two names were proposed for crocodile-line archosaurs before Crurotarsi was erected. The first, Pseudosuchia, was established as a stem-based clade in 1985.[5] It includes crocodiles and all archosaurs more closely related to crocodiles than to birds. The second, Crocodylotarsi, was named in 1988, possibly as a replacement for Pseudosuchia.[6] The name Pseudosuchia, meaning "false crocodiles", has been used for over a century, and traditionally included aetosaurs. As a clade, Pseudosuchia includes the group Eusuchia, or "true crocodiles". Crocodylotarsi may have been named to remove confusion, but as a stem-based clade it is synonymous with Pseudosuchia. Because Pseudosuchia was named first, it has precedence. Crurotarsi traditionally contains the same archosaurs as Pseudosuchia, but as a node-based clade it is not synonymous.[7]
Below is a cladogram after Nesbitt & Norell (2006) and Nesbitt (2007) with Crurotarsi in its traditional sense encompassing just crocodile-line archosaurs:[8][9]
Archosauriformes |
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Cladogram after Brusatte, Benton, Desojo and Langer (2010):[10]
Archosauriformes |
| ||||||||||||||||||||||||||||||||||||||||||||||||
In 2011, Sterling J. Nesbitt found phytosaurs to be the sister taxon of Archosauria, and therefore not crocodile-line archosaurs. Because phytosaurs are included in the definition of Crurotarsi, this change in their
Below is a cladogram modified from Nesbitt (2011) showing the new changes:[1]
Archosauriformes |
| ||||||||||||||||||||||||||||||||||||||||||
References
- ^ S2CID 83493714.
- ^ a b c Sereno, P.C.; Arcucci, A.B. (1990). "The monophyly of crurotarsal archosaurs and the origin of bird and crocodile ankle joints". Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen. 180: 21–52.
- .
- S2CID 86687464.
- ^ Gauthier, J.A.; Padian, K. (1985). "Phylogenetic, functional, and aerodynamic analyses of the origin of birds and their flight". In Hecht, M.K.; Ostrom, J.H.; Viohl, G.; Wellnhofer, P. (eds.). The Beginnings of Birds. Eichstatt: Freunde des Jura-Museums. pp. 185–197.
- ^ Benton, M.J.; Clark, J.M. (1988). "Archosaur phylogeny and the relationships of the Crocodylia". In Benton, M.J. (ed.). Phylogeny and Classification of the Tetrapods. Vol. 1. Oxford: Clarendon Press. pp. 295–338.
- .
- PMID 16600879.
- hdl:2246/5840.
- S2CID 59148006.
- Benton, M. J. (2004). Vertebrate Paleontology (3rd ed.). Blackwell Science.
- Dunham, W. (2008-09-12). "Lucky break allowed dinosaurs to rule Earth". Reuters. Retrieved 2012-01-14.
- Brusatte, S. L.; Benton, M. J.; Ruta, M.; Lloyd, G. T. (2008-09-12). "Superiority, Competition, and Opportunism in the Evolutionary Radiation of Dinosaurs" (PDF). S2CID 13393888. Archived from the original(PDF) on 2014-06-24. Retrieved 2012-01-14.