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Ancyloceratidae is a family of heteromorphic ammonites that lived during the Early Cretaceous. Their shells begin as a loose spiral with whorls not touching which then turns into a straight shaft that ends in a J-shape hook or bend at end. Coarse ribbing and spines are common. Ancyloceratidae is the type family for the Ancyloceratoidea and of the suborder Ancyloceratina. They are found in Lower Cretaceous, Upper Hauterivian to perhaps Lower Albian sediments. Genera include: *''Ancyloceras'' - type genus *''Acrioceras'' *''Aspinoceras'' *''Epancyloceras'' *''Hoheneggericeras'' *''Lytocrioceras'' *''Megacrioceras'' *''Pseudocrioceras'' *''Rugacrioceras'' *''Uhligia'' Ancyloceratidae are derived from the Crioceratidae, a family of Lower Cretaceous ammonites with loosely wound, open planispiral shells, probably originating from within the suborder Lytoceratina. ==References== * 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「Ancyloceratidae」の詳細全文を読む スポンサード リンク
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