USGS D1987 [Pierre Shale]: Early/Lower Maastrichtian, Wyoming

List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
Cephalopoda - Ammonitida - Scaphitidae
Discoscaphites sp. Meek 1870
sp. nov.
Cephalopoda - Ammonitida - Baculitidae
Baculites clinolobatus Elias 1933
Bivalvia - Myalinida - Inoceramidae
Inoceramus subcircularis
Inoceramus cf. incurvus
originally entered as "Inoceramus cf. incurvus"
? Inoceramus fibrosus (Meek and Hayden 1857)
originally entered as "? Inoceramus fibrosus"
unclassified
Bryozoa indet. Ehrenberg 1831
pyriporoid bryozoan
see common names

Geography
Country:United States State/province:Wyoming County:Niobrara
Coordinates: 43.3° North, 104.3° West (view map)
Paleocoordinates:49.7° North, 79.1° West
Basis of coordinate:estimated from map
Geographic resolution:small collection
Time
Period:Cretaceous Epoch:Late/Upper Cretaceous
Stage:Maastrichtian 10 m.y. bin:Cretaceous 8
*Epoch:Senonian
Key time interval:Early/Lower Maastrichtian Ammonoid zone: Baculites clinolobatus
Age range of interval:70.60000 - 66.00000 m.y. ago
* legacy (obsolete) database fields
Stratigraphy
Geological group:Montana Formation:Pierre Shale
Stratigraphic resolution:bed
Stratigraphy comments: AGE: Early Maastrichtian, on the basis of ammonoid biostratigraphy; Baculites clinolobatus zone.
Lithology and environment
Primary lithology:gray lithified silty "shale"
Secondary lithology: "limestone"
Environment:offshore Tectonic setting:cratonic basin
Geology comments: "Shale, silty; weathers light gray; contains many gray and brown weathering ls concretions, some having fossils."
Taphonomy
Modes of preservation:body
Size of fossils:macrofossils
Collection methods and comments
Collection methods:mechanical,field collection
Reason for describing collection:biostratigraphic analysis
Museum repositories:USGS
Collection method comments: "[collected] from concretions"
Taxonomic list comments:"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."
Metadata
Database number:1577
Authorizer:J. Alroy Enterer:M. Sommers
Modifier:M. Carrano Research group:marine invertebrate
Created:1999-05-17 15:57:32 Last modified:2012-01-31 16:47:24
Access level:the public Released:1999-05-17 15:57:32
Creative Commons license:CC BY
Reference information

Primary reference:

45. 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]