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''Reedsoceras'' is a large member of the discosorid (Nautiloidea) family Westonoceratidae from the middle and upper Ordovician of North America. ''Reedsoceras'' was named as a genus characterized by rapidly expanding exogastric cyrtocones with unconstricted apertures and straight sutures. The siphuncle is close to the venter, which is the externally convex side of the shell, and is composed of very short, broadly rounded segments. Structure of the siphuncle wall is unknown. ''Reedsoceras'' seems to be derived from ''Simardoceras'' and to be more closely related to a group that also includes ''Sinclairoceras'' than to other westonoceratids, especially those with long narrowing body chambers and bent back exogastric phragmocones like ''Winnipegoceras''. ==References== * Flower, R.H.and Curt Teichert 1957. The Cephalopod Order Discosorida. University of Kansas Paleontological Contributions, Mollusca, Article 6. July 1957 * Teichert, C 1964. Nautiloidea -Discosorida. Treatise on Invertebrate Paleontology Part K. Geological Soc of America 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「Reedsoceras」の詳細全文を読む スポンサード リンク
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