Pierre Shale (USGS D1948) (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: lower unnamed shale Member (Pierre Shale Formation), Campanian (83.6 - 72.1 Ma)

• bed-level stratigraphic resolution

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

• "shale, weathers light gray, bentonitic, contains a little fibrous calcite and rarely a limestone concretion."

Reposited in the USGS

Collection methods: mechanical,

• "[collected] from a ls concretion."

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 1637: authorized by John Alroy, entered by Mike Sommers on 19.05.1999

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."
Bivalvia
 Myalinida - Inoceramidae
Inoceramus cf. balchii clam
originally entered as "Inoceramus cf. balchii"
Gastropoda
 Neogastropoda - Fasciolariidae
? Anomalofusus sp. Wade 1916 snail
originally entered as "? Anomalofusus sp."
 Basommatophora - Siphonariidae
Anisomyon borealis Morton 1842 pulmonate
Cephalopoda
 Ammonitida - Placenticeratidae
 Ammonitida - Diplomoceratidae
Solenoceras sp. Conrad 1860 ammonite