USGS D1935 [Pierre Shale] (Cretaceous of the United States)

Where: Niobrara County, Wyoming (43.3° N, 104.3° W: paleocoordinates 49.4° N, 72.4° W)

• coordinate estimated from map

• small collection-level geographic resolution

When: Didymoceras nebrascense ammonoid zone, Pierre Shale Formation, Late/Upper Campanian (83.5 - 70.6 Ma)

• COMMENTS: From lower unnamed shale. AGE: Late Campanian, on the basis of ammonoid biostratigraphy; Didymoceras nebrascense zone.

• bed-level stratigraphic resolution

Environment/lithology: offshore; lithified, gray, yellow shale and limestone

• "shale, weathers med. gray; contains a few scattered yellowish gray weathering ls concretions, with more persistent beds of concretions at base and 56 ft and 76 ft above base; basal concretions have cone-in-cone structure."

Preservation: original aragonite

Reposited in the USGS

Collection methods: mechanical,

• "[collected] from a concretion 24 ft above base"

Primary reference: J. R. Gill, W. A. Cobban, and P. M. Kier. 1966. The Red Bird Section of the Upper Cretaceous Pierre Shale in Wyoming. United States Geological Survey Professional Paper 393-A:1-73 [J. Alroy/M. Sommers/A. Clement]more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 1649: authorized by John Alroy, entered by Mike Sommers on 25.05.1999

Creative Commons license: CC BY (attribution)

Taxonomic list

• "The fossils are ordinarily well-preserved. Most of the cephalopod shells and the inner nacreous layer of Inoceramus are aragonitic, especially specimens from above the Red Bird Silty Member. Shell material and specimens from the Red Bird member and the upper 50' of the underlying Mitten Member is partially transformed to calcite...Ammonites...of the [mid-upper third] of the Mitten Member are...entirely aragonite whereas shell material [of underlying material] is completely transformed to calcite."
Show authors, comments, and common names
Bivalvia
 Cardiida - Arcticidae
Tenea circularis
 Myalinida - Inoceramidae
Inoceramus aff. turgidus
Inoceramus aff. turgidus Anderson 1958 clam
originally entered as "Inoceramus aff. turgidus"
Cephalopoda
 Ammonitida - Nostoceratidae
Didymoceras nebrascense
Didymoceras nebrascense Meek and Hayden 1856 ammonite