Protosuchia

Protosuchia Temporal range: Late Triassic - Late Cretaceous
A skeleton of Protosuchus richardsoni in the American Museum of Natural History
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	Archosauria
Clade:	Pseudosuchia
Clade:	Crocodylomorpha
Clade:	Crocodyliformes
Informal group:	† Protosuchia Mook, 1934
Subgroups
See text.

Protosuchia is a group of extinct Mesozoic crocodyliforms. They were small in size (~1 meter in length) and terrestrial. In phylogenetic terms, Protosuchia is considered an informal group because it is a grade of basal crocodyliforms, not a true clade.

Classification

Recent phylogenetic analyses have not supported Protosuchia as a natural group. However, two studies found a clade of Late Triassic-Early Jurassic animals: ^{[1] [2]}

• Edentosuchus
• Hemiprotosuchus
• Orthosuchus
• Protosuchus

Both of these studies also found a clade more closely related to Hsisosuchus and Mesoeucrocodylia consisting of Late Jurassic-Late Cretaceous genera: ^{[1] [2]}

• Neuquensuchus
• Shantungosuchus
• Sichuanosuchus
• Zosuchus

However, other possible protosuchians from the Late Cretaceous of China-Mongolia, the Gobiosuchidae ( Gobiosuchus and Zaraasuchus ), have been found to be either intermediate between these two clades, ^[1] or members of the Sichuanosuchus clade. ^[2] There is also another family of Late Jurassic-Late Cretaceous genera, the Shartegosuchidae (e.g. Kyasuchus , Shartegosuchus and Nominosuchus ).

Below is a cladogram from Fiorelli and Calvo (2007). ^[2] Protosuchians are marked by the green bracket.

Crocodylomorpha Terrestrisuchus Dibothrosuchus Crocodyliformes Gobiosuchidae Gobiosuchus Zaraasuchus Orthosuchus Protosuchidae Protosuchus Hemiprotosuchus "Kayenta Form" Edentosuchus Mesoeucrocodylia "Fruitachampsa" Zosuchus Sichuanosuchus Shantungosuchus Neuquensuchus Hsisosuchus Metasuchia Neosuchia Peirosauridae Notosuchia

Protosuchians

References

1. Pol D, Ji S-a, Clark JM, Chiappe LM. 2004. Basal crocodyliforms from the Lower Cretaceous Tugulu Group (Xinjiang, China), and the phylogenetic position of Edentosuchus. Cretaceous Research25: 603-622.
2. Fiorelli LE, Calvo JO. 2007. The first "protosuchian" (Archosauria: Crocodyliformes) from the Cretaceous (Santonian) of Gondwana. Arquivos do Museu Nacional, Rio de Janeiro65 (4): 417-459.