Coniacian age cephalopods are rare in Utah's rocks, they are found in isolated concretions in the Mancos Shale in the Vernal and Emery areas and in it's equivalents near Manti and the Kaiparowits Plateau. These rocks were deposited in the Sevier Foreland Basin.
References: Reeside, J. B., Jr., 1932, The Upper Cretaceous Ammonite Genus Barroisiceras in the United States, U.S.G.S. Professional Paper 170; Cobban, W. A., 1951, Scaphitoid Cephalopods of the Colorado Group, U.S.G.S. Professional Paper 239; Cobban, W. A., 1976, Ammonite Record from the Mancos Shale of the Castle Valley-Price-Woodside Area, East-Central Utah, B.Y.U. Geology Studies Vol.22, Pt.3; Kennedy, W. J., and Cobban, W. A., 1991, Coniacian Ammonite Faunas from the United States Western Interior, The Palaeontological Association (London), Special Papers in Palaeontology No. 45
Scaphites preventricosus Cobban 1951
Allocrioceras hazzardi Young 1963
Eutrephoceras n. sp., 60mm dia., a
Top from Left: Placenticeras fritschi de Grossouvre 1894, 80mm dia., Allocrioceras hazzardi Young 1963,
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