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Clypeoceras
''Clypeoceras'' is an ammonite with an involute discoidal shell from the Lower Triassic. ==Description== The shell of ''Clypeoceras'' is laterally compressed, involute, discoidal; whorls strongly embracing and deeply indented by the next inner whorl, increasing rapidly in height. Sides slightly convex, sloping outward to a rather narrow venter, which may be angular or rounded but never with keels or grooves. Surface smooth or ornamented with radial striae and folds. Body chamber short.〔J.P. Smith,1932. Lower Triassic Ammonoids of North America. US Geological Survey Professional Paper 167.〕 Suture ceratitic with deep asymmetric saddles and broad serrated lobes. Sutures have a ''Meekoceras'' stage produced during early growth with broad asymmetric saddles and narrower serrated lobes,〔 indicating a phylogenetic relationship.
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「Clypeoceras」の詳細全文を読む
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