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''Agathiceras'' is a subglobose goniatitid from the family Agathiceratidae, widespread and locally abundant in Lower Pennsylvanian to Middle Permian sediments, e.g. the Urals, Sicily, and Texas. ''Agathiceras'', named by Gemmellaro in 1887 from the Middle Permian Sicilian species, ''A. suessi'', has a broadly rounded outer edge, known as the venter, being at the lower side of the animal during life, and a deeply impressed innerside, the dorsum which corresponds with the back or dorsal side of the animal. The sutures are goniatitic with three lateral and one dosolateral lobes on either side. Those that are external are spatulate, those hidden are V-shaped. The siphuncle is primitive with the septal necks pointing to the rear, a condition known as retrosiphonate. ''Agathiceras'' is thought to be derived from ''Proshumardites'' according to Saunders ''et al''. (1999), which is thought to be derived from ''Dombaties''; all of which are included in the Agathiceratidae. ''Dombarites'' is presumed to have its origin in ''Goniatites'', type genus of the Goniatitidae ==Species== * ''Agathiceras anceps'' * ''Agathiceras applanatum'' * ''Agathiceras applini'' * ''Agathiceras ciscoense'' * ''Agathiceras contractum'' * ''Agathiceras divisum'' * ''Agathiceras frechi'' * ''Agathiceras girtyi'' * ''Agathiceras jilinense'' * ''Agathiceras mediterraneum'' * ''Agathiceras suessi'' * ''Agathiceras sundaicum'' * ''Agathiceras tornatum'' * ''Agathiceras uralicum'' * ''Agathiceras verkhoyanicum'' * ''Agathiceras vulgatum'' 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「Agathiceras」の詳細全文を読む スポンサード リンク
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