West end of the Fort Peck reservoir at the Robinson Bridge (Cretaceous to of the United States)

Where: Fergus County, Montana (47.6° N, 108.4° W: paleocoordinates 54.4° N, 74.5° W)

• coordinate stated in text

When: Judith River Formation (Montana Group), Middle Campanian to Middle Campanian (83.5 - 70.6 Ma)

Environment/lithology: terrestrial; sandstone

• Regression of the sea (R3) exposed a terrestrial surface upon which the fluvial Judith River Formation was laid down; this formation extends as far east as Glasgow (Jensen and Varnes, 1964) but is best exposed in Blaine and Choteau counties.
• The Judith River Formation consists of sandstones, shales, and an occasional lignite.

Size class: microfossils

Preservation: original sporopollenin

Collection methods: surface (in situ),

Primary reference: J. W. Hall. 1969. Studies on fossil Azolla: Primitive types of megaspores and massulae from the Cretaceous. American Journal of Botany 56(10):1173-1180 [R. Lupia/B. Wilborn/B. Wilborn]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 34016: authorized by Rick Lupia, entered by Brooke Wilborn on 12.08.2003

Creative Commons license: CC BY (attribution)

Taxonomic list

Show authors, comments, and common names
Polypodiopsida
 Salviniales - Polypodiidae
Azolla simplex n. sp.
Azolla simplex n. sp.
megaspore and massulae