USGS D8836, Hempstead Co. [Saratoga Chalk] (Cretaceous of the United States)

Where: Hempstead County, Arkansas (33.7° N, 93.7° W: paleocoordinates 37.8° N, 65.4° W)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: Nostoceras hyatti ammonoid zone, Saratoga Chalk Formation (Navarro Group), Late/Upper Campanian (83.5 - 70.6 Ma)

• STRATIGRAPHIC RELATIONS: From the Saratoga Chalk, which regionally overlies the Marlbrook Marl, and is overlain by the Nacatoch Sand Fm, all of the Navarro Gp. AGE: Late Campanian on the basis of ammonite biostratigraphy; Nostoceras hyatti zone. STRATIGRAPHIC POSITION: From 6.1-7.6 m (20-25 ft) above base.

• bed-level stratigraphic resolution

Environment/lithology: lithified lime mudstone and lithified, calcareous sandstone

• ENVIRONMENT: Shallow marine cabonate setting.
• SPECIFIC LITHOLOGY: Chalk and calcareous sand. LITHIFICATION: Lithified, on the basis of figured specimens.

Size class: macrofossils

Preservation: cast, mold/impression

Collected by Cobban in 1973; reposited in the USNM

Collection methods: surface (in situ),

• COLLECTOR: W.A. Cobban, 1973. REPOSITORY: USNM, Washington DC.

Primary reference: W. J. Kennedy and W. A. Cobban. 1993. Ammonites from the Saratoga Chalk (Upper Cretaceous), Arkansas. Journal of Paleontology 67(3):404-434 [A. Hendy/A. Hendy]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 83044: authorized by Austin Hendy, entered by Austin Hendy on 06.08.2008

Creative Commons license: CC BY (attribution)

Taxonomic list

• COVERAGE: Exhaustive for ammonoids, other groups may be present, but are not listed. NOMENCLATURE: An authoritative publication, with modern nomenclature and species-resolution identifications.
 Ammonitida - Pachydiscidae
Pachydiscus (Pachydiscus) arkansanus Stephenson 1941 ammonite
 Ammonitida - Nostoceratidae
"Nostoceras (Nostoceras) helicinum" = Nostoceras helicinus, "Nostoceras (Nostoceras) pauper" = Nostoceras pauper
"Nostoceras (Nostoceras) helicinum" = Nostoceras helicinus Shumard 1861 ammonite
"Nostoceras (Nostoceras) pauper" = Nostoceras pauper Whitfield 1892 ammonite