USGS Mesozoic loc. 27047, Sun River area, Western Montana (Jurassic of the United States)

Where: Montana (47.6° N, 112.8° W: paleocoordinates 40.4° N, 52.2° W)

• coordinate stated in text

• small collection-level geographic resolution

When: Upper Siltstone Member (Sawtooth Formation), Bathonian (168.3 - 166.1 Ma)

• from lower part of upper member of Sawtooth formation; the Upper Siltstone member is probably of Bathonian age

• group of beds-level stratigraphic resolution

Environment/lithology: marine; lithified siltstone

• The upper siltstone member consists of yellow calcareous siltstone and fine-grained sandstone.

Size class: macrofossils

Reposited in the USGS

• collection was made by M. R. Mudge in 1958

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 68862: authorized by Martin Aberhan, entered by Sabine Nürnberg on 10.02.2007

Creative Commons license: CC BY (attribution)

Taxonomic list

Show authors, comments, and common names
Bivalvia
 Pholadomyida - Pholadomyidae
Pholadomya inaequiplicatus
 Pandorida - Laternulidae
Cercomya punctata
Cercomya punctata Stanton 1899 clam
 Cardiida - Cardiidae
Protocardia sp.
Protocardia sp. Beyrich 1845 cockle
 Cardiida - Anthracosiidae
"Pleuromya subcompressa" = Myacites (Pleuromya) subcompressa
"Pleuromya subcompressa" = Myacites (Pleuromya) subcompressa Meek 1873 clam
 Arcida - Parallelodontidae
Grammatodon sp.
Grammatodon sp. Meek and Hayden 1860 clam
Cephalopoda
 Ammonitida - Perisphinctidae
Cobbanites sp.
Cobbanites sp. Imlay 1962 ammonite
 Ammonitida - Cardioceratidae
Arctocephalites sp.