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Trechnotheria is a group of mammals that includes the therians and some fossil mammals from the Mesozoic Era. In the Jurassic through Cretaceous periods, the group was endemic to what would be Asia and Africa〔 (【引用サイトリンク】 work = Paleobiology Database )〕 Trechnotheria has been assigned various ranks, but was originally called a "superlegion" by the original author.〔 〕 One reference has defined the Trechnotheria as the clade comprising the last common ancestor of ''Zhangheotherium'' and living therian mammals, and all its descendants.〔 〕 == Characteristics == Like most Mesozoic mammal groups, early trechnotherians are known mainly from their teeth. Hence, one of most prominent features of this group is the "hypertrophied postvallum/prevallid shearing mechanism", along with other dental characters. Features of the shoulder blade, tibia, humerus, and ankle joint also diagnose this clade.〔 〕 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「Trechnotheria」の詳細全文を読む スポンサード リンク
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