Pierre Shale (USGS D1909, D1910) (Cretaceous of the United States)

Where: Niobrara County, Wyoming (43.3° N, 104.3° W: paleocoordinates 49.2° N, 71.6° W)

• coordinate estimated from map

• small collection-level geographic resolution

When: Red Bird Silty Member (Pierre Shale Formation), Campanian (83.6 - 72.1 Ma)

• bed-level stratigraphic resolution

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

• "shale; silty; weathers med. gray, contains a few small weathering fossiliferous concretions."

Reposited in the USGS

Collection methods: mechanical,

• "[collected] from concretions 15 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 1670: 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
Bryozoa
  -
Bryozoa indet.
Bryozoa indet. Ehrenberg 1831
pyriporoid bryozoan
Cephalopoda
 Ammonitida - Baculitidae
Baculites gregoryensis
Baculites gregoryensis Cobban 1951 ammonite
Gastropoda
 Basommatophora - Siphonariidae
Anisomyon borealis
Anisomyon borealis Morton 1842 pulmonate
Bivalvia
 Myalinida - Inoceramidae
Inoceramus aff. proximus
Inoceramus aff. proximus clam
originally entered as "Inoceramus aff. proximus"