Where: Dawson County, Montana (47.0° N, 104.8° W: paleocoordinates 53.3° N, 78.0° W)

• coordinate estimated from map

• outcrop-level geographic resolution

When: Pierre Shale Formation, Early/Lower Maastrichtian (70.6 - 66.0 Ma)

• Baculites baculus/grandis zone. At these localities there is no clear distinction between the B. baculus and B. grandis zones; hence, they have been considered to be a single stratum in this area (cf. Bishop, 1967).

• bed-level stratigraphic resolution

Environment/lithology: marine; lithified, concretionary shale

Size class: macrofossils

Reposited in the AMNH

Primary reference: J. C. Grier and J. W. Grier. 1998. New findings of the ammonite Rhaeboceras, including a new species, from the Pierre Shale of eastern Montana. Journal of Paleontology 72:473-476 [M. Clapham/M. Clapham]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 178358: authorized by Matthew Clapham, entered by Matthew Clapham on 01.05.2016

Creative Commons license: CC BY (attribution)