Crocodylomorpha

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Crocodylomorpha
Fossil range: Late Triassic - Recent

Protosuchus, an early crocodylomorph

Scientific classification

Kingdom:	Animalia
Phylum:	Chordata
Class:	Sauropsida
Infraclass:	Archosauromorpha
(unranked)	Crurotarsi
Superorder:	Crocodylomorpha Hay, 1930

Suborders

The Crocodylomorpha are an important group of archosaurs that include the crocodilians and their extinct relatives.

1 Evolutionary history
2 Phylogenetic definition
3 Taxonomy
- 3.1 Phylogeny
4 References
5 External links

[edit] Evolutionary history

When their extinct species and stem group are examined, the crocodylian lineage (clade Crurotarsi) proves to have been a very diverse and adaptive group of reptiles. Not only are an ancient group of animals, at least as old as the dinosaurs, they also evolved into a great variety of forms. The earliest forms, the Sphenosuchians, evolved during the Late Triassic, and were highly gracile terrestrial forms built like greyhounds. Several terrestrial species during the Cretaceous evolved herbivory, such as Simosuchus clarki and Chimaerasuchus paradoxus. During the Jurassic and the Cretaceous marine forms in the family Metriorhynchidae such as Metriorhynchus evolved forelimbs that were paddle-like and had a tail similar to modern fish. Dakosaurus andiniensis a closely related species to Metriorhynchus had a skull that was adapted to eat large marine reptiles.

During Mesozoic and early Tertiary times the Crocodylomorpha were far more diverse than they are now. Triassic forms were small, lightly built, active terrestrial animals. These were supplanted during the early Jurassic by various aquatic and marine forms. The Later Jurassic, Cretaceous, and Tertiary saw a wide diversity of terrestrial and semi-aquatic lineages. "Modern" crocodilians do not appear until the Late Cretaceous.

[edit] Phylogenetic definition

The Crocodylomorpha are defined phylogenetically by Sereno 2005 as "The most inclusive clade containing Crocodylus niloticus (Laurenti 1768) but not Poposaurus gracilis Mehl 1915, Gracilisuchus stipanicicorum Romer 1972, Prestosuchus chiniquensis Huene 1942, Aetosaurus ferratus Fraas 1877."

This a stem-based definition and therefore includes all taxa closer to extant crocodilians than to other crurotarsan clades.

[edit] Taxonomy

The following classification is from the Bristol University webpage on Crocodylomorpha. All these taxa are extinct except for the three Eusuchian families shown here. There are in addition many other, less well-known groups that are not included in this current listing. Mikko's Phylogeny Archive provides a more detailed cladogram

Subdivision Crurotarsi
- Superorder Crocodylomorpha
  - Suborder Sphenosuchia
  - Clade Crocodyliformes (Order Crocodilia in the broad sense)
    - Family Gobiosuchidae (extinct)
    - Family Hsisosuchidae (extinct)
    - Family Shartegosuchidae (extinct)
    - Suborder Protosuchia (extinct)
    - Suborder Thalattosuchia (extinct)
    - Suborder Metasuchia* (extinct)
    - Order Crocodilia (strict sense)
      - Superfamily Gavialoidea
        
        Family Gavialidae
      - Superfamily Crocodyloidea
        
        Family Mekosuchidae (extinct)
        
        Family Crocodylidae
      - Superfamily Alligatoroidea
        
        Family Nettosuchidae (extinct)
        
        Family Alligatoridae

[edit] Phylogeny

Cladogram after Clark (1994), Ortega et al. (2000), and Turner & Calvo (2005).

Crocodyliformes
  |--Eopneumatosuchus
  |-?Microchampsa
  `-+-?Artzosuchus
    |--Protosuchia
    `--+--Shartegosuchidae
       `--Mesoeucrocodylia
           |-?Hsisosuchus
           `--+-?Gobiosuchidae
              `--+-?Simosuchus
                 |--Ziphosuchia
                 `--+-?Uruguaysuchus
                    `--+--Araripesuchus
                       `--+--Peirosauridae
                          `--+--Trematochampsidae
                             `--Neosuchia
                                 |-?Elosuchidae
                                 |--Peirosauridae
                                 `--+--Comahuesuchus
                                    |--Itasuchus
                                    |--Atoposauridae
                                    `--+--+--Eutretauranosuchus
                                       |  `--+-?+--Dyrosauridae
                                       |     |  `--+--Sarcosuchus
                                       |     |     `--Terminonaris
                                       |     `--+--Pholidosauridae
                                       |        `--+--Thalattosuchia
                                       |           `--+--Pelagosuchus
                                       |              `--+--Teleosauridae
                                       |                 `--Metriorhynchidae
                                       `--+--Goniopholididae
                                          `--+--Bernissartia
                                             `--+--Gilchristosuchus
                                                |--Rugosuchus
                                                |-?Paralligatoridae
                                                `--Eusuchia
                                                    |--Hylaeochampsa
                                                    `--+--Allodaposuchus
                                                       `--Crocodilia

[edit] References

Benton, M. J. (2004), Vertebrate Palaeontology, 3rd ed. Blackwell Science Ltd
Hay, O. P. 1930 (1929-1930). Second Bibliography and Catalogue of the Fossil Vertebrata of North America. Carnegie Institution Publications, Washington, 1,990 pp.
Sereno, P. C. 2005. Stem Archosauria—TaxonSearch [version 1.0, 2005 November 7]
- Taxon Search - Crocodylomorpha