|
''Zittelloceras'' is an extinct nauiloid genus from the order Oncocerida which are among a large group of once diverse and numerous shelled cephalopods, now represented by only a handful of species. ''Zittleoceras'', which is included in the family Oncoceratidae, is characterized by subcircular or sightly depressed cyrtoconic shells with ventral, suborthochoanitic empty siphuncles; the shell surface typically with crenulated transverse frills or distinct noncrenulated annulations. ''Zittleoceras'' has been found in middle and upper Ordovician sediments in North America and Scotland. (Sweet, 1964) ==See also== * Nautiloid * * List of nautiloids 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「Zittelloceras」の詳細全文を読む スポンサード リンク
|