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Pistosauroidea is a group of marine reptiles within the superorder Sauropterygia that first appeared in the latter part of the Early Triassic and were the ancestors of plesiosaurs. Pistosauroids are rare in Triassic marine assemblages, and are represented by only a few fossils from central Europe, the United States, and China. Recent phylogenetic analyses consider the Triassic pistosauroids to be a paraphyletic grouping, meaning that they do not form a true clade. Plesiosauria is now placed within Pistosauroidea, while the traditional pistosauroids are successively more basal, or primitive, sauropterygians. Below is a cladogram of pistosauroid relationships from Cheng ''et al.'' (2006):〔 }} }} }} }} }} Below is a cladogram of pistosauroid relationships from Ketchum & Benson, 2011: }} }} }} ==References== 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「Pistosauroidea」の詳細全文を読む スポンサード リンク
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