USGS Mesozoic loc. 18711, Sun River area, Western Montana (Jurassic to of the United States)

Where: Montana (47.8° N, 112.7° W: paleocoordinates 40.2° N, 51.7° W)

• coordinate estimated from map

• small collection-level geographic resolution

When: Middle Shale Member (Sawtooth Formation), Bajocian to Bajocian (170.3 - 166.1 Ma)

• zone 1 from lower part of middle shale member of Sawtooth formation, 12 ft above base of formation; the Middle Shale member is probably of Bajocian to Bathonian age

• bed-level stratigraphic resolution

Environment/lithology: marine; lithified shale

• The middle shale member of the Sawtooth formation consists of gray to black shales.

Size class: macrofossils

Reposited in the USGS

• collection was made by C. F. Deiss in 1941

Primary reference: R. W. Imlay. 1962. Jurassic (Bathonian or Early Callovian) Ammonites from Alaska and Montana. Geological Survey Professional Paper 374-C:1-32 [M. Aberhan/S. Nurnberg]more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 68830: authorized by Martin Aberhan, entered by Sabine Nürnberg on 09.02.2007

Creative Commons license: CC BY (attribution)

Taxonomic list

Show authors, comments, and common names
Cephalopoda
 Belemnoidea -
Belemnitida indet.
Belemnitida indet. Zittel 1895 belemnite
Belemnite fragments
Scaphopoda
 Dentaliida - Dentaliidae
Dentalium sp.
Dentalium sp. Linnaeus 1758 tusk shell
Bivalvia
 Ostreida - Ostreidae
Ostrea sp.
Ostrea sp. Linnaeus 1758 oyster
 Trigoniida - Trigoniidae
Trigonia montanaensis
Trigonia montanaensis Meek 1873 clam
 Carditida - Astartidae
Astarte cf. packardi, Astarte meeki
Astarte meeki Stanton 1899 clam
 Cardiida - Tancrediidae
Tancredia sp.
Tancredia sp. Lycett 1850 clam
 Nuculida - Nuculidae
Nucula sp.
Nucula sp. Lamarck 1799 nut clam