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''Sactorthceras'' is an orthoceratoid genus (subclass Nautiloidea s.l.) known from the Middle Ordovician of eastern North America (NY), Norway and Korea and is the type genus of the Sactorthoceratidae. ''Sactorthceras'' was named by Kobayashi in 1934 to include smooth or striated, straight or slightly curved longicones with short camerae and slender, subcentral, suborthochoanitic siphuncles with segments slightly inflated and no cameral deposits. ''Sactorthocras'' has also been recognized in the Silurian Racine Formation of Wisconsin, and from the Ordovician of China and Iran. Related genera include ''Centroonoceras'' and ''Sigmocycloceras'' ==-References-== *Sweet, Walter C. 1964. Nautiloidea -Orthocerida. Treatise on Invertebrate Paleontology, Part K. Geological Soc. of America and Univ of Kansas press. * ( Sactorthoceras ref Paleodb ) 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「Sactorthoceras」の詳細全文を読む スポンサード リンク
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