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''Clitendoceras'' is a member of the Endocerida from the Lower Ordovician (m-u Canadian) with an elongate shell with a slight downward, endogastric, curvature and a siphuncle that lies along the ventral margin. Common for endocerids, the chambers are short and the septa close spaced with sutures sloping forward across the back of the shell. Septal necks are short in the young, lengthening in the adult. Endocones are simple, but with the ventral side of the last formed projecting forward. The endosiphotube running down the middle is arched on top and somewhat flat on the lower side. ''Clitendoceras'' appears early in the Domingian stage, Lower Ordovician, probably derived from ''Proendoceras'', and is the likely ancestor of the mostly compressed and breviconic pilocerids as well as of more similar forms such as ''Mcqueenoceras''. == References == *Flower, R. H. 1964; Memoir 12,The Nautiloid Order Ellesmeroceratida (Cephalopoda),pp145,150,158.NMBM&MR, Socorro N.M. *Flower, R.H. 1976; Ordovician Cephalopod Faunas and Their Role in Correlation, pp 531-535; proceedings pub. Paleontological Association, Gr Br. *Teichert, C, 1964, ''Clitendoceras'', p 166 in Proterocameroceratidae, pp 166- 170 in the ''Treatise on Invertebrate Paleontology'' Vol K. GSA and Univ Kansas Press. 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「Clitendoceras」の詳細全文を読む スポンサード リンク
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