Pierre Shale (USGS D1924, D1925) (Cretaceous of the United States)

Where: Niobrara County, Wyoming (43.3° N, 104.3° W: paleocoordinates 49.2° N, 71.7° 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, concretionary, brown, gray, silty, calcareous shale and concretionary, shelly/skeletal, gray, green, silty limestone

• "shale; weathering light gray; contains at top irregularily shaped gray and brown weathering fossiliferous ls concretions; at base has a ridge forming bed of larger closely spaced silty fossiliferous ls concretions that are light olive gray where fresh, and tan to dark yellowish orange where weathered."
• "shale; weathering light gray; contains at top irregularily shaped gray and brown weathering fossiliferous ls concretions; at base has a ridge forming bed of larger closely spaced silty fossiliferous ls concretions that are light olive gray where fresh, and tan to dark yellowish orange where weathered."

Reposited in the USGS

Collection methods: mechanical,

• "[collected] from both beds of concretions"

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 1657: 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
Bivalvia
 Myalinida - Inoceramidae
"Inoceramus tenuilineatus" = Inoceramus (Cataceramus) tenuilineatus
"Inoceramus tenuilineatus" = Inoceramus (Cataceramus) tenuilineatus Hall and Meek 1855 clam
 Cardiida - Mactridae
Cymbophora sp.
Cymbophora sp. Gabb 1869 clam
Cephalopoda
 Ammonitida - Baculitidae
Baculites scotti
Baculites scotti Cobban 1958 ammonite
 Ammonitida - Nostoceratidae
Exiteloceras sp., Didymoceras sp., Anaklinoceras mortoni
Exiteloceras sp. Hyatt 1894 ammonite
sp. nov.
Didymoceras sp. Hyatt 1900 ammonite
sp. nov.
 Ammonitida - Pachydiscidae
"Anapachydiscus complexus" = Menuites
"Anapachydiscus complexus" = Menuites ammonite
Gastropoda
 Neogastropoda - Fasciolariidae
? Cryptorhytis sp.
? Cryptorhytis sp. Meek 1876 snail
originally entered as "? Cryptorhytis sp."