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''Permoceras'', the sole member of the Permoceratidae, is a coiled nautiloid with a smooth, compressed involute shell, whorls higher than wide, earlier whorls hidden from view. The venter is rounded as are the ventral and umbilical shoulders, the flanks flattened. The siphuncle is ventrally subcentral. The suture, which is most characteristic, has a deep, narrow pointed ventral lobe and large, asymmetrical pointed lobes on either side. ''Permoceras'' is included in the nautilid superfamily, Trigonocerataceae, and is derived from the Mississippian (L Carb) - Triassic Grypoceratidae. ''Permoceras'' was first identified in the Lower Permian of Timur in the East Indies and named by Miller and Collinson in 1953 ''Permoceras'' almost precisely resembles ''Pseudonautilus'' from the Upper Jurassic. ==See also== * Nautiloid * * List of nautiloids 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「Permoceras」の詳細全文を読む スポンサード リンク
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