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''Donetzoceras'' is a genus belonging to the goniatitid family Gonioglyphioceratidae ; extinct ammonoids which are shelled cephalopods more closely related to squid, octopus and other coleoids than to the superficially similar ''Nautilus'' ''Donetzoceras'' has a relatively small, thick-discoidal shell, the inner whorls evolote, later stages involute. Sculpture consists of nodelike riblets and umbilical plications which disappear at maturity.Growth lines form shallow ventral sinus and ventrolateral salients. The ventral lobe pointed with a median saddle about half as high as entire ventral lobe itself. ''Donetzoceras'' is the earliest genus now included in the Gonioglyphioceratidae. ''Donetzoceras'' is from the middle and upper Upper Carboniferous (Pennsylvanian) ==''References''== * Goniat: () * Saunders et al. 1999; Evolution of Complexity in Paleozoic Ammonoid Sutures, Supplementary Material; Science Mag. () * (The Paleobiology Database ) accessed on 10/01/07 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「Donetzoceras」の詳細全文を読む スポンサード リンク
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