Where: Phillips County, Montana (47.9° N, 108.4° W: paleocoordinates 41.4° N, 49.8° W)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: Rierdon Formation (Ellis Group), Early/Lower Callovian (164.7 - 161.2 Ma)

• About 24 feet above base of Rierdon formation

• group of beds-level stratigraphic resolution

Environment/lithology: marine; lithified lithology not reported

Size class: macrofossils

Preservation: mold/impression

Reposited in the USNM

Primary reference: B. Kummel. 1954. Jurassic nautiloids from western North America. Journal of Paleontology 28:320-324 [M. Clapham/M. Clapham/M. Clapham]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 180718: authorized by Matthew Clapham, entered by Matthew Clapham on 29.07.2016

Creative Commons license: CC BY (attribution)