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''Bickmorites'' is an extinct nautiloid cephalopod genus known from the upper Ordovician to the middle Silurian of North America and northern Europe (Norway). ''Bickmorites'' has a gyroconic shell, coiled such that whorls are not in contact, although close. The surface is strongly ribbed; ribs slant dorso-ventrally toward the apex. The siphuncle is narrow, located slightly ventral of the center. Septal necks are straight, making the siphuncle orthochoanitic. ''Bickmorites'' seems to bridge the temporal gap between the Upper Ordovivian barrandeoceratid ''Antiplectoceras'' and the Middle Silurian barrandoeceratids ''Gasconsoceras'', ''Laureloceras'', and ''Savageoceras''. ==References== * Walter C. Sweet, 1964. Naautiloidea-Barrandeocerida. Treatise on Invertebrate Paleongology, Part K. Geological Society of America. *(Bickmorites ) 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「Bickmorites」の詳細全文を読む スポンサード リンク
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