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William A. Cobban

Publications and source records attributed to William A. Cobban.

9 recordsLinked to original sources
USGS2006

A USGS Zonal Table for the Upper Cretaceous Middle Cenomanian--Maastrichtian of the Western Interior of the United States Based on Ammonites, Inoceramids, and Radiometric Ages

From the Introduction: This provisional table is based mainly on the molluscan fossil record of the central and northern parts of the Western Interior of the United States. Some of the ammonite zones are known in Europe, such as Watinoceras devonense, Collignoniceras woollgari, Prionocyclus germari, Scaphites hippocrepis, Didymoceras stevensoni, and Didymoceras cheyennense, whereas more than one-half of the inoceramid zones are known also in Europe. A few of the ammonite zones are known from only a few localities, but the diagnostic species may occur in abundance. Among these are the zones of Acanthoceras granerosense, A. bellense, Dunveganoceras problematicum, Burroceras clydense, Watinoceras devonense, Collignoniceras praecox, and Scaphites mariasensis. All fossils listed in the table are in the national collection housed in Building 810 at the Federal Center, Denver, Colorado

Open-File Report↗
USGS2000

Heteromorph ammonites from the Upper Campanian (Upper Cretaceous) Baculites cuneatus and Baculites reesidei zones of the Pierre Shale in Colorado, USA

Calcareous sandstone concretions in the Upper Cretaceous Pierre Shale in Middle Park and in the Fort Collins area of Colorado in the U.S. Western Interior contain heteromorph ammonites of the families Nostoceratidae HYATT, 1894, and Diplomoceratidae SPATH, 1926. The following species are described: Nostoceras cf. N. approximans (CONRAD, 1855), Nostoceras cf. N. obtusum HOWARTH, 1965, N. larimerense sp. nov., Nostoceras cf. N. splendidum (SHUMARD, 1861). Didymoceras aurarium sp. nov., D. draconis (STEPHENSON, 1941), Cirroceras conradi (MORTON, 1841), Anaklinoceras minutum sp. nov., Solenoceras texanum (SHUMARD, 1861), Solenoceras cf. S. reesidei STEPHENSON, 1941, Lewyites oronensis (LEWY, 1969), and Lewyites? sp. All these species are migrants from the Gulf coastal region. Didymoceras draconis and Cirroceras conradi are also known from the Delaware-New Jersey area, and these two species, together with Solenoceras texanum are known from as far away as Israel.

Colorado↗
USGS1990

Ammonites and some characteristic bivalves from the Upper Cretaceous Frontier Formation, Natrona County, Wyoming

The Frontier Formation in Natrona County, Wyoming, consists of two or three members of mostly shallow-water marine shale, siltstone, and sandstone. From oldest to youngest, these units are the Belle Fourche Member, the informal member of Emigrant Gap, and the Wall Creek Member. The members are separated by disconformities, and locally the Wall Creek Member rests on the Belle Fourche Member. Molluscan fossils are present in all the members, but only the Wall Creek Member contains a great variety of species. Ammonites and inoceramid bivalves are most important in zoning the Frontier Formation. Seven of the twelve established ammonite zones of middle and late Cenomanian age in the Western Interior can be recognized in the Belle Fourche Member. Two zones of middle Turonian age are present in the member of Emigrant Gap, and three zones of late Turonian age are present in the Wall Creek Member.

Wyoming↗
USGS1988

Some acanthoceratid ammonites from upper Cenomanian (Upper Cretaceous) rocks of Wyoming

Ammonites of the genera Calycoceras, Dunueganoceras, and Metoicoceras are useful in zoning the Frontier Formation of central and north-central Wyoming and the mostly undifferentiated rocks of northeastern Wyoming that are equivalent in age to the Belle Fourche Shale and Greenhorn Formation. The oldest of the four zones identified contains Dunueganoceras pondi Haas, Calycoceras canitaurinum (Haas), C. newboldi (Kossmat), and Metoicoceras praecox Haas. Calycoceras newboldi has not previously been reported from North America. The second zone is characterized by the new species Dunueganoceras problematicum, Calycoceras rubeyi, C. aff. C. canitaurinum, and Metoicoceras frontierense. A subspecies, D. problematicum natronense, is recognized in this zone in one area of central Wyoming. The third zone has Dunueganoceras albertense (Warren) and Metoicoceras mosbyense Cobban, as well as a new geographic subspecies, D. albertense regale. The fourth and youngest zone may be that of Dunueganoceras conditum Haas. Dunueganoceras is not known in the western interior of the United States above the zone of D. conditum. Metoicoceras, however, ranges higher and terminates in the species M. geslinianum (d'Orbigny).

Professional Paper↗