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| regnum = Animalia | phylum = Mollusca | classis = Cephalopoda | subclassis = Nautiloidea | ordo = Pseudorthocerida | familia = Carbactinoceratidae | genus_authority = Schindewolf, 1943 | subdivision_ranks = Genera | subdivision = 〔 (【引用サイトリンク】 work = The Paleobiology Database ) 〕 * ''Aploceras'' * ''Carbactinoceras'' * ''Rayonnoceras'' }} Carbactinoceratidae is a family of extinct cephalopods with external shells that lived around 325 million years ago, during the Carboniferous period. They were the last group of orthocones to attain sizes exceeding one meter (three feet) in length. One specimen of the carbactinoceratid species ''Rayonnoceras solidiforme'', recently found in Arkansas, was measured at long. == Characters == Shells of carbactinoceratids are usually straight or slightly curved, with a large central or subcentral siphuncle. The first chamber at the apex is long and conical, the first septum slightly convex with the a septal perforation about one third of the shell diameter and a cyrtochoanitic septal neck (tubular or funnel-like projection from the back of the septum. The first siphuncle segment is elongated, subsequent ones formed during growth of the animal are subglobular (rounded but not spherical). Organic deposits are formed within the siphuncle through which run central,and radial canals along with a seam along the connecting rings known as a perispatium. 〔 〕 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「Carbactinoceratidae」の詳細全文を読む スポンサード リンク
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