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''Hutchemys'' (Hutchison's turtle) is an extinct genus of softshell turtles from the late Cretaceous (Maastrichtian stage) to the late Paleocene of New Mexico, Montana, Wyoming and Utah, USA. It was first named by Walter G. Joyce, Ariel Revan, Tyler R. Lyson and Igor G. Danilov in 2009, and the type species is ''Hutchemys rememdium''. ''H. rememdium'' is known from the holotype YPM PU 16795, which consists of a nearly complete postcranial skeleton, and from the referred specimen YPM PU 16781, found in the Ekalaka Member of the Fort Union Formation, Montana. Another referred specimen, YPM PU 14985, was found in the Cedar Point Quarry, Wyoming. The second species, ''H. arctochelys'', is known from the holotype YPM PU 16319, a nearly complete carapace, and from the paratypes YPM PU 16320, YPM PU 16321, YPM PU 16322, YPM PU 16238. All specimens of ''H. arctochelys'' were recovered from the same quarry of the Tongue River Member, Fort Union Formation, near Burns Mine of Montana. A possible third species is represented by the unnamed specimen UCMP 130000 from the Paleocene Tullock Formation of Montana. ''Aspideretes? nassau'' (YPM PU 11566) from the Fort Union Formation, Duffy’s Ranch of Sweet Grass County, Montana was also assigned to ''Hutchemys sp''. The generic name honors John Howard Hutchison, a turtle paleontologist. Hutchison himself named later in 2009 two new genera of extinct softshell turtles from New Mexico, Montana, Wyoming and Utah: ''Plastomenoides'' (two new species: ''P. lamberti'' (type) and ''P. tetanetron'') and ''Derrisemys'' (new species: ''D. sterea'' (type) and new combination ''D. acupictus'' (''Plastomenus'' )). In 2011, Joyce and Lyson noted that ''P. lamberti'' and ''Hutchemys rememdium'' are based on the same type specimen (YPM PU 16795) and therefore ''P. lamberti'' and ''Plastomenoides'' are objective junior synonyms of ''H. rememdium'' and ''Hutchemys''. ''P. tetanetron'' Hutchison, 2009 is also cogeneric with ''H. rememdium''. They also found that ''D. sterea'' is the closest relative of ''P. tetanetron'' and therefore both ''D. sterea'' and ''D. acupictus'' were reassigned to ''Hutchemys''. == Phylogeny == Cladogram after Joyce, Revan, Lyson and Danilov, 2009:〔 |label2=†Plastomeninae |2= }} |label2=Trionychinae |2= |2= }} |2= }} }} }} Cladogram after Joyce and Lyson, 2011:〔 }} }} }} }} }} 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「Hutchemys」の詳細全文を読む スポンサード リンク
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