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''Collignociceras'' is a strongly ribbed and tuberculate, evolute ammonite from the Upper Cretaceous of the western U.S. and Europe belonging to the ammonitid family Collignoniceratidae. The type is ''Collignoniceras woollgari'', named by Mantell in 1822 for specimens from Sussex, England. The shell is compressed in early growth stages, with rounded or high and clavate siphonal tubercles tending to form a serrate keel, straight or slightly sinuous ribs and weak umbilical and strong ventrolateral tubercles. later whorls tend to be squarer in section with exaggerated ventrolateral tubercles. Two subspecies are known from the Turonian of western North America, ''C. woollgari wooolgari'' and ''C. woollgari regulari''. ''C. w. woollgari'' has been found with ''Mammites depressus'' at the top of the lower shale tongue and lowermost overlying Tres Hermanos sandstone member of the Mancos Shale in New Mexico, in a shale bed at the top of the Greenhorn Formation in Colorado, and alone in sandstone and shale in the upper Frontier Formation in Wyoming. The slightly younger ''C. w. regulari'' is known from the lower Carlile Shale, which overlies the Greenhorn. It has been found in U. S. western interior from as far west as northern Arizona and eastern Utah and from New Mexico to Montana. ==References== * Arkell ''et al.'', 1957, Mesozoic Ammonoidea, Treatise on Invertebrate Paleontology Part L. Geological Soc. of America, Univ of Kansas Press. R.C. Moore, (Ed) * W. A. Cobban and Hook, S. C. 1979, ''Collignoniceras woollgari wooollgari'' (Mantell) ammonite fauna from Upper Cretaceous of Western Interior, United States. Memoir 37, New Mexico Bureau of Mines&Mineral Resources, Socorro NM. 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「Collignoniceras」の詳細全文を読む スポンサード リンク
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