USGS D11377, Section 13 [Smoky Hill Shale Mbr, Niobrara Fm] (Cretaceous of the United States)

Where: Colfax County, New Mexico (36.3° N, 104.7° W: paleocoordinates 39.4° N, 71.6° W)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: Magadiceramus subquadratus inoceramid zone, Smoky Hill Shale Member (Niobrara Formation), Late/Upper Coniacian (89.3 - 85.8 Ma)

• STRATIGRAPHIC RELATIONS: From the Smoky Hill Shale Mbr of the Niobrara Fm, which regionally overlies the Fort Hays Limestone. AGE: Coniacian, on the basis of inoceramid and ammonite biostratigraphy; Prionocyclus quadratus biozone. STRATIGRAPHIC POSITION: Bed 25, from near top of Smoky Hill Shale in this section, 65 ft above base of sandy unit. PJW: Magadiceramus subquadratus zone is Late Coniacian.

• bed-level stratigraphic resolution

Environment/lithology: coastal; lithified, fine-grained, brown, yellow sandstone and lithified, fine-grained, calcareous sandstone

• ENVIRONMENT: Shallow marine siliciclastic environment.
• SPECIFIC LITHOLOGY: Calcarenite within Sandstone, yellowish brown, fine grained, shaly, in thin lenses rarely more than one inch thick. LITHIFICATION: Lithified, on the basis of figured specimens.

Size class: macrofossils

Preservation: cast, mold/impression

Collected by Scott, Cobban, Merewether, Buckhorn in 1984; reposited in the UNSM

• COLLECTORS: Scott, Cobban, Merewether, and Buckhorn (1984). REPOSITORY: USNM.

Primary reference: G. R. Scott, W. A. Cobban, and E. A. Merewether. 1986. Stratigraphy of the Upper Cretaceous Niobrara Formation in the Raton basin, New Mexico. New Mexico Bureau of Mines and Mineral Resources Bulletin 115:1-34 [A. Hendy/A. Hendy]more details

Purpose of describing collection: general faunal/floral analysis

PaleoDB collection 82248: authorized by Austin Hendy, entered by Austin Hendy on 25.07.2008

Creative Commons license: CC BY (attribution)

Taxonomic list

• COVERAGE: Probably not exhaustive, but comprising representative and common bivalves and cephalopods. NOMENCLATURE: Not an authoritative publication, but with modern nomenclature, and identifications to species-level.
Bivalvia
 Myalinida - Inoceramidae
Inoceramus (Magadiceramus) aff. soukupi, "Inoceramus (Magadiceramus) subquadratus" = Magadiceramus subquadratus
"Inoceramus (Magadiceramus) subquadratus" = Magadiceramus subquadratus Schlüter 1887 clam
Includes subspecies: I (M) subquadratus crenelatus, I (M) subquadratus subquadratus
Cephalopoda
 Ammonitida - Baculitidae
Baculites codyensis Reeside 1927 ammonite
Baculites asper Morton 1830 ammonite
 Ammonitida - Collignoniceratidae