Cenomanian (Late Cretaceous) Ammonites

The Tropic Shale was deposited in the Sevier Foreland Basin during Cenomanian time, as part of the Western Interior Seaway. Ammonites are found in exposures of this formation in what is now Grand Staircase-Escalante National Monument and around the towns of Orderville and Alton.

References: White, C. A., 1877, Report upon the Invertebrate fossils collected in portions of Nevada, Utah, Colorado, New Mexico and Arizona, by parties of the expeditions of 1871, 1872, 1873, and 1874, U. S. Geographical and Geological Explorations and Surveys West of the 100th Meridian Report (Wheeler), vol. 4, pt. 1; Stanton, T. W., 1893, The Colorado Formation and it's Invertebrate Fauna, U.S.G.S. Bulletin 106; Hyatt, A., 1903, Pseudoceratites of the Cretaceous: edited by T. W. Stanton, U.S.G.S. Monograph 44; Swenson, A. J., 1962, Anisoceratidae and Hamitidae (Ammonoidea) from the Cretaceous of Texas and Utah, B.Y.U. Geology Studies Vol. 9, pt. 2

Euomphaloceras septemseriatum Zone

Jim Jenks collected the following from the Tropic Shale
in the area around Henrieville, Garfield County, Utah.

  Some of the first Cephalopods reported from the state of Utah.  C. A. White described fossils collected by members of the Wheeler Survey on Upper Kanab Creek,
the taxonomy has changed quite often since they were first reported.

Metoicoceras geslinianum (d'Orbigny) 1850
reported as Buchiceras swallovi (Shumard) by White in 1877
and as M. whitei, M. kanabense and M. gibbosum by Hyatt in 1904
M. kanabense was named after Kanab Creek which flows near Alton

Euomphaloceras septemseriatum (Cragin) 1893
reported as Acanthoceras? kanabense by Stanton in 1894
and as Kanabiceras septemseriatum (Cragin) in the 1957 Treatise
again, named after Kanab Creek

Pseudocalycoceras angolaense (Spath) 1931

Sciponoceras gracile (Shumard) 1860
reported by Stanton in 1893 as Baculites gracilis Shumard

Allocrioceras annulatum (Shumard) 1860
reported by White in 1877 as Helicoceras pariense
named after Paria Creek which flows near Tropic

Worthoceras vermiculus (Shumard) 1860

The following are from my collection

Top: Sciponoceras gracile (Shumard)1860
Lower Left & Lower Center: Metoicoceras geslinianum (d'Orbigny) 1850
Right Middle: Allocrioceras annulatum (Shumard) 1860
Lower Right: Euomphaloceras septemseriatum (Cragin) 1893

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