Trilobites of the Ute Formation

Ute Limestone, Ehmaniella Biozone, Marjuman Stage, Middle Cambrian. Blacksmith Fork, Bear River Range (part of Wasatch Range) and Ute Mt., Wasatch Range, Utah.

Trilobites:

Alokistocare subcoronatum (Hall and Whitfield, 1877)

Ehmaniella sp.

Elrathiella spp.

Elrathia sp.

Glossopleura sp.

Kootenia quadriceps (Hall and Whitfield, 1877)

Proehmaniella sp.

Trilobite occurences divided into subzones (oldest at base):

Altiocculus Subzone, Ehmaniella Biozone:

Alokistocare subcoronatum (Hall and Whitfield, 1877)

Kootenia quadriceps (Hall and Whitfield, 1877)

Ehmaniella Subzone, Ehmaniella Biozone:

Ehmaniella sp.

Elrathiella spp.

Elrathiella Subzone, Ehmaniella Biozone:

Elrathiella spp.

Proehmaniella Subzone, Ehmaniella Biozone:

Proehmaniella sp.

Glossopleura Biozone:

Glossopleura sp.

Comments:

        The Ute Formation was originally defined to include a 2,000 ft sequence of carbonates and shale between the Cambrian basal quartzites, and the Middle Ordovician Swan Peak quartzites. The Ute Limestone has been redefined to include approx. 700 ft. of mainly limestones of the Ehmaniella Biozone, Marjuman Stage, and is bounded below by the Langston Formation, and above by the Blacksmith Formation. The lowermost portion of the Ute limestone includes the upper part of the Glossopleura Biozone.

        There are some problems with the age assignments of many trilobite species in the Ute, as both Walcott and Resser made little distinction between shale at the Spence horizon (Glossopleura Biozone) and the Ute horizon (Ehmaniella Biozone) since the talus mixed these two formational faunas. Conversely, Resser put all of the limestone specimens into his "Ptarmigania Strata" thus mixing the Naomi Peak Limestone (Albertella Biozone) faunas with the thin limestone layers from the Spence Shale which contained the Glossopleura Biozone faunas.

        The faunal list above is taken from Sundberg (1999), who collected the Ute Limestone for the type species of Alokistocare, A. subcoronatum. If anyone has a more complete faunal list (of the Ute Fm. restricted), please contact us.

References:

Sundberg, F. A. 1999. Redescription of Alokistocare subcoronatum (Hall and Whitfield, 1877), the type species of Alokistocare, and the status of Alokistocaridae, Resser, 1938b (Ptychopariida: Trilobita, Middle Cambrian). Journal of Paleontology 73:1126–1143.