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The Genus ''Hemichoanella'' is a small, extinct, orthoconic nautiloid cephalopod from the Lower Ordovician of Western Australia assigned to the orthoceratoid family, ''Baltoceratidae''. ''Hemichoanella'' and the Baltoceratidae are part of the subclass of once diverse and numerous shelled cephalopods known as the Nautiloidea. ''Hemichoanella'' is characterized by its straight, smooth longiconic shell with a circular cross section, large marginal siphuncle and sutures with deep narrow ventral lobes. Septal necks are hemichoanitic, the source of the name, and reach halfway to the previous septa. Connecting rings are thick and uniform, each extending from the tip of a septal neck to the tip of the preceding neck. (T&G 1954) ''Hemichoanella'' was named by Teichert and Glenister in 1954 (T&G 1954) for specimens found in Emanuel Creek, Kimberley Division, Western Australia. The type species, ''Hemichoanella canningi'' (Teichert & Glenister) is named in honor of Alfred Canning, who from 1906 to 1908, explored the eastern part of the Desert Basin and who discovered and opened up the Canning Stock Route. ''Hemichoanella'' is considered a particularly advanced baltoceratid (T&G 1954) which differs from ''Baltoceras'' in having longer septal necks. ==References== * Teichert & Glenister (T&G) 1954, (Hemichoanella canningi) Bulletins of American Paleontology, Museum of Comparative Zoology, Harvard University, () * 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「Hemichoanella」の詳細全文を読む スポンサード リンク
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