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''Cosmonautilus'' is a cephalopod genus included in the nautilid family Clydonautilidae. Its shell is involute, with only the outer whorl exposed. Early whorls are with nodes on ventral shoulder, which disappear on the later growth staged. Later whorls are smooth. ''Cosmonautilus'' has been found in Siberian Russia, e.g. in eastern Taimyr and in the lower Lena River region, and in Alaska on Gravina Island, and California from Shasta County in the US, as well as Mexico, India, and Timor. ''Callaionautilus'' and ''Clydonautilus'' are among related genera included in the Clydonautilidae. ==References== * Bernhard Kummel, 1964. Nautiloidea-Nautilida. Treatise on Invertebrate Paleontology, Part K. Geological Society of America. * (''Cosmonautilus'' ) in Fossilworks gateway. 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「Cosmonautilus」の詳細全文を読む スポンサード リンク
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