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''Caenagnathus'' ('recent jaw') is a genus of caenagnathid oviraptorosaurian dinosaur from the late Cretaceous (Campanian; ~75 million years ago). It is known from partial remains including lower jaws, a tail vertebra, hand bones, and hind limbs, all found in the Dinosaur Park Formation of Alberta, Canada. ''Caenagnathus'' weighted about a maximum of .〔 ==Classification== This dinosaur has a confusing history. In 1936, a set of jaws were found, and later given the name ''Caenagnathus'', meaning 'recent jaw'; they were first thought to be those of a bird.〔Sternberg, R.M. (1940). A toothless bird from the Cretaceous of Alberta. ''Journal of Paleontology'' 14(1):81-85.〕 In 1988, a specimen from storage since 1923 was discovered and studied. This fossil were used to link the discoveries of several fragmentary oviraptorosaur species into a single dinosaur, which was assigned to the genus ''Chirostenotes'', originally named for a pair of hands that were long considered to come from the same animal as ''Caenagnathus''. Since the first name applied to any of these remains was ''Chirostenotes'', this was the only name recognized as valid for many years.〔Currie, P.J., and Russell, D.A. (1988). Osteology and relationships of ''Chirostenotes pergracilis'' (Saurischia, Theropoda) from the Judith River (Oldman) Formation of Alberta, Canada. ''Canadian Journal of Earth Sciences'' 25:972-986.〕 However, further study and new discoveries of more complete caenagnathid skeletons cast doubt on the idea that all of these fossils belonged to the same species. Some studies even suggested that while ''Chirostenotes'' was an advanced oviraptorosaurian and possibly an oviraptorid, ''Caenagnathus'' was thought to potentially have been a more primitive animal.〔Holtz, Thomas R. Jr. (2010) ''Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages,'' (Winter 2010 Appendix. )〕 The status and relationships of ''Caenagnathus'' to other caenagnathid oviraptorosaurians began to be resolved with the discovery of more complete specimens in 2014 and 2015. The description of ''Anzu wyliei'' in 2014 represented the first nearly complete caenagnathid, and helped to clarify the differences between the more fragmentary specimens. Phylogenetic analyses found ''Caenagnathus collinsi'' to be more closely related to ''Anzu'' than to ''Chirostenotes''. A second species which had previously been referred to ''Caenagnathus'', "Caenagnathus" ''sternbergi'', was found to be sister taxon to the grouping of ''Anzu'' and ''Caenagnathus'' in one 2014 analysis. In 2015, new fossil remains were found to belong to ''Caenagnathus collinsi''. These appeared to be intermediate in size and anatomy between the smaller ''Chirostenotes'' and the larger ''Anzu'', lending support to their hypothesized relationships. These bones can be distinguished from ''Chirostenotes'' and contemporary ''Leptorhynchos'' by features of the limbs, specifically the hand and metatarsals. }} }} }} }} |2=Oviraptoridae }} }} 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「Caenagnathus」の詳細全文を読む スポンサード リンク
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