羊角菊石

羊角菊石（學名：），又名公羊齒菊石，是生存於白堊紀的一屬菊石，生活在中等深度的大陸棚海域中。其化石分布於歐洲、非洲、亞洲和美洲。

 特徵 
羊角菊石的外殼盤捲得很鬆，外觀猶如盤曲的羊角，因而得名。其殼階互不相連。殼階的大小由內而外增長得很快。殼上飾有肋條，長有結節、較結實的粗肋條之間有二至三個無結節且較為纖細的肋條隔著。腹是圓形的。

 物種 
Crioceras (Acanthodiscus) 
Crioceras dilatatum 
Crioceras munieri 
Crioceras obliquatum 
Crioceras simplex 
Crioceratites (Crioceratites) 
Crioceratites (Emericiceras) 
Crioceratites andersoni 
Crioceratites barrabei 
Crioceratites bituberculatus 
Crioceratites coniferus 
Crioceratites duvalii 
Crioceratites emerici 
Crioceratites heterocostatus 
Crioceratites krenkeli 
Crioceratites latus 
Crioceratites leivaensis 
Crioceratites loryi 
Crioceratites panescorsii 
Crioceratites portarum 
Crioceratites tehamaensis 
Crioceratites tener 
Crioceratites yollabollium 

 參考文獻 

 外部連結 
 Crioceratites  in the Paleobiology Database

 延伸閱讀 
 Simon & Schuster's Guide To Fossils (Nature Guide Series) by Paolo Arduini
 , Part L, Ammonoidea,--Ancyloceratiaceae; Geological Society of America 1957, reprinted 1990.

Y
Y
Y