Crocodyliformes

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Crocodyliformes
Temporal range: Late Triassic–Recent, 225–0Ma
Protosuchus BW.jpg
Protosuchus, an early crocodyliform
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Superorder: Crocodylomorpha
Clade: Crocodyliformes
Hay, 1930
Clades

See text.

Crocodyliformes is a clade of crurotarsan archosaurs, the group often traditionally referred to as "crocodilians."

In 1988, Michael J. Benton and James M. Clark argued that all traditional names for well-known groups of animals should be restricted to their crown clades, that is, used only for natural groups comprising all living members of any given lineage. This posed a problem for the crocodilians, because the name Crocodylia, while used in various ways by various scientists, had always included not only living crocodilians but many of their extinct ancestors known only from the fossil record.[1]

Benton and Clark's solution to this issue was to restrict the name Crocodylia to the group containing modern alligators, crocodiles, and gharials, plus any extinct members of those specific families. The traditional group "Crocodylia" was replaced with the name Crocodyliformes, which included many of the extinct families the new definition left out. Clark and Benton did not initially provide an exact definition for Crocodyliformes, but in 2001 Paul Sereno and colleagues defined it as the clade including Protosuchus richardsoni and the Nile crocodile, plus all descendants of their common ancestor.[2]

Chris Brochu agreed with the assessment that Crocodylia as a name has never had stable contents, and that a series of clades larger than the crown group Crocodylia (including Crocodyliformes and the slightly more inclusive clade Crocodylomorpha) was a good solution.[3] However, in a 2008 paper Jeremy Martin and Benton, the authors reversed the previous opinion (co-authored by Benton) that Crocodylia should be restricted to the crown group, suggesting that Crocodyliformes should be considered a synonym of a more inclusive Crocodylia, and thus replaced.[4] Brochu and colleagues rejected this proposal, arguing that the crown definition of Crocodylia is the standard meaning both within and beyond the crocodyliform systematics community.[5]


Phylogeny[edit]

The cladogram below illustrates the relationships of crocodyliformes, based on an overview by Martin and Benton, 2008.[4]

Crocodyliformes

Protosuchia


unnamed

Mesoeucrocodylia


Eusuchia

Isisfordia


unnamed

Hylaeochampsa


Crocodylia

Gavialoidea


unnamed

Alligatoroidea



Crocodyloidea








In 2012, paleontologists Mario Bronzati, Felipe Chinaglia Montefeltro, and Max C. Langer conducted a broad phylogenetic analysis to produce supertrees of Crocodyliformes, including 184 species. The most parsimonious trees were highly resolved, meaning the phylogenetic relationships found in the analysis were highly likely. Below is a consensus tree from the study:[6]



Kayentasuchus walkeri


Crocodyliformes
Protosuchia

Orthosuchus stormbergi





Protosuchus richardsoni



Hemiprotosuchus leali





Kayenta Form



Edentosuchus tienshanensis








Zaraasuchus shepardi



Las Hoyas Croc



Gobiosuchus kielanae





Eopneumatosuchus colberti




Zosuchus davidsoni





Sichuanosuchus shuhanensis



Sichuanosuchus huidongensis





Shantungosuchus hangjinensis



Shantungosuchus chuhsiensis



Shantungosuchus brachycephalus



Neuquensuchus universitas








Shartegosuchus asperopalatum



Fruita Form (Fruitachampsa callisoni)






Hsisosuchus dashanpuensis



Hsisosuchus chungkingensis




Notosuchia


Araripesuchus wegeneri




Araripesuchus tsangatsangana



Araripesuchus buitreraensis




Araripesuchus patagonicus



Araripesuchus gomesii








Uruguaysuchus terrai



Uruguaysuchus aznarezi





Libycosuchus brevirostris




Simosuchus clarki





Malawisuchus mwakasyungutiensis



Candidodon itapecuruense






Notosuchus terrestris




Comahuesuchus brachybuccalis




Mariliasuchus amarali




Yacarerani boliviensis



Pakasuchus kapilimai



Adamantinasuchus navae








Stratiotosuchus maxhechti



Pehuenchesuchus enderi



Pabwehshi pakistanensis



Iberosuchus macrodon



Eremosuchus elkoholicus



Doratodon



Bergisuchus dietrichbergi



Baurusuchus salgadoensis



Baurusuchus pachechoi




Chimaerasuchus paradoxus




Sphagesaurus huenei



Sphagesaurus montealtensis







Sebecus huilensis



Sebecus icaeorhinus





Itaborai Croc



Bretesuchus bonapartei













Anatosuchus minor





Barcinosuchus gradilis



Itasuchus jesuinoi




Miadanasuchus oblita



Trematochampsa taqueti



Caririsuchus camposi






Kaprosuchus saharicus



Mahajangasuchus insignis



Peirosauridae

Hamadasuchus rebouli




Montealtosuchus arrudacamposi



Uberabasuchus terrificus




Peirosaurus torminni



Lomasuchus palpebrosus








Neosuchia











References[edit]

  1. ^ Benton, M.J. and Clark, J.M. (1988). "Archosaur phylogeny and the relationships of the Crocodylia." Pp. 295–338 in Benton, M.J. (ed.), The phylogeny and classification of the Tetrapods, volume 1. Oxford: Clarendon Press.
  2. ^ Sereno, P.C., Larson, H.C.E., Sidor, C.A. and Gado, B. (2001). "The giant crocodyliform Sarcosuchus from the Cretaceous of Africa." Science, 294: 1516–1519.
  3. ^ Brochu, C.A. (2003). "Phylogenetic approaches toward crocodylian history." Annu. Rev. Earth Planet. Sci., 31: 357–397.
  4. ^ a b Martin, J.E. and Benton, M.J. (2008). "Crown Clades in Vertebrate Nomenclature: Correcting the Definition of Crocodylia." Systematic Biology, 57: 1,173 — 181.
  5. ^ Brochu, A.C., Wagner, J.R., Jouve, S., Sumrall, C.D. and Densmore, L.D. (2009). "A correction corrected: consensus over the meaning of Crocodylia and why it matters" Systematic Biology, 58: 537-543.
  6. ^ Bronzati, M.; Montefeltro, F. C.; Langer, M. C. (2012). "A species-level supertree of Crocodyliformes". Historical Biology: 1. doi:10.1080/08912963.2012.662680.  edit