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''Uranoceras'' is a barrandeocerid genus from the Middle Silurian belonging to the family Uranoceratidae, characterized by its loosely coiled, gyroconic shell of 1.5 to 2 subquadrate whorls. The shell of ''Uranoceras'' is typically smooth but may have growth lines that form a hyponomic sinus on the venter. The Siphuncle is large, displaced slightly ventral from the center. Septal necks are straight; connecting rings cylindrical, thin, and strongly contracted where they meet the necks. ''Uranoceras'' has been found in Indiana, Illinois, and Wisconsin in the United States; Anticosti Island in Canada; and in both central and northern Europe. ==References== * Sweet, Walter C. 1964. Nautiloidea-Barrandeocerida. Treatise on Invertebrate Paleontology, Part K. Geol Soc of America and Univ Kansas Press. * Sepkoski, J.J. Jr. 2002. A compendium of fossil marine animal genera. D.J. Jablonski & M.L. Foote (eds.). ''Bulletins of American Paleontology'' 363: 1–560. (Sepkoski's Online Genus Database (CEPHALOPODA) ) 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「Uranoceras」の詳細全文を読む スポンサード リンク
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