Protosuchia

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.

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

See text.

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]

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

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 Research 25: 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 Janeiro 65 (4): 417-459.


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