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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.〔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.〕 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.〔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.〕 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.〔Brochu, C.A. (2003). "Phylogenetic approaches toward crocodylian history." ''Annu. Rev. Earth Planet. Sci.'', 31: 357–397.〕 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.〔Martin, J.E. and Benton, M.J. (2008). "Crown Clades in Vertebrate Nomenclature: Correcting the Definition of Crocodylia." ''Systematic Biology'', 57: 1,173 — 181.〕 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.〔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.〕 ==Phylogeny== The cladogram below illustrates the relationships of crocodyliformes, based on an overview by Martin and Benton, 2008.〔 }} }} }} }} }} 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: }} |2= }} |3= }} |2= }} }} |2= |11= }} }} }} }} }} }} }} |2= }} }} }} |2=Neosuchia }} }} }} }} }} }} }} }} }} }} 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Crocodyliformes」の詳細全文を読む スポンサード リンク
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