Pierre Shale (USGS D1977) (Cretaceous of the United States)

Where: Niobrara County, Wyoming (43.3° N, 104.3° W: paleocoordinates 49.8° N, 78.5° W)

• coordinate estimated from map

• small collection-level geographic resolution

When: upper unnamed shale Member (Pierre Shale Formation), Maastrichtian (72.1 - 66.0 Ma)

• bed-level stratigraphic resolution

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

• "Shale, dark gray, silty. weathers light medium gray; contains many brown weathering ls concretions 1-2 ft thick and 1.3-8 ft diam. crowded with Inoceramus typicus. a thin layer of light gray fibrous calcite lies at top of unit."

Reposited in the USGS

Collection methods: mechanical,

• "[collected] 22 feet 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 1591: authorized by John Alroy, entered by Mike Sommers on 17.05.1999

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
 Myalinida - Inoceramidae
Inoceramus typicus
 Cardiida - Cardiidae
Protocardia rara
 Cardiida - Veneridae
Dosiniopsis deweyi
Dosiniopsis deweyi Meek and Hayden 1856 venus clam
Scaphopoda
 Dentaliida - Dentaliidae
Dentalium gracile