Prionocyclus hyatti
Biozone
These fossils were found in the Ferron Sandstone Member of the Mancos Shale in eastcentral Utah. These rocks were deposited in the Sevier Foreland Basin .
References: 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; Molenaar, C. M., and Wilson, B. W., 1990, The Frontier Formation and Associated Rocks of Northeastern Utah and Northwestern Colorado, U.S.G.S. Bulletin 1787-M; Molenaar, C. M., and Cobban, W. A., 1991, Middle Cretaceous Stratigraphy on the South and East Sides of the Uinta Basin, Northeastern Utah and Northwestern Colorado, U.S.G.S. Bulletin 1787-P; Kennedy, W. J., Cobban, W. A., and Landman, N. H., 2001, A Revision of the Turonian Members of the Ammonite Subfamily Collignoniceratidae from the United States Western Interior and Gulf Coast, American Museum of Natural History Bulletin 267.Prionocyclus hyatti (Stanton) 1893
Robust form of P. hyatti, 42mm dia.
Placenticeras pseudoplacenta (Hyatt) 1903
From the Lower Ferron Sandstone Member
Scaphites carlislensis Morrow 1935
The only specimen of Scaphites I have found from this biozone in Utah,
45mm long, from the Lower Ferron Member near Mounds.