Threeforks Shale, Madison Co., Montana (Devonian of the United States)

Where: Madison County, Montana (45.7° N, 112.0° W: paleocoordinates 14.9° S, 46.8° W)

• coordinate based on political unit

• outcrop-level geographic resolution

When: Platyclymenia zone, Three Forks Shale Formation, Middle Famennian (370.6 - 364.7 Ma)

• species of ammonoid found by the author correspond to the Oberdevon III, the lower Platyclymenia horizon in the European stratigraphic column [JA: originally entered as late Devonian, but the lower Platyclymenia horizon corresponds to the Pa. trachytera conodont zone and is middle Famennian]

• formation-level stratigraphic resolution

Environment/lithology: marine; shale and limestone

• author gives no detailed description of lithology where she collected; however, through historic descriptions included in the text, the formation is divided into two shale units divided by limestone.

Collection methods: surface (in situ),

Primary reference: P. J. Renzetti. 1961. Fauna of the Threeforks Shale (Devonian) of Southwestern Montana. 1-342 [A. Miller/K. Layou/M. Uhen]more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 6988: authorized by Arnold Miller, entered by Karen Layou on 18.04.2000

Creative Commons license: CC BY (attribution)

Taxonomic list

Show authors, comments, and common names
Cephalopoda
 Clymeniida - Platyclymeniidae
Platyclymenia sp., Platyclymenia sp. n. sp., "Platyclymenia polypleura" = Pleuroclymenia americana
Platyclymenia sp. Hyatt 1884 ammonite
Platyclymenia sp. n. sp. Hyatt 1884 ammonite
Platyclymenia n. sp. A
"Platyclymenia polypleura" = Pleuroclymenia americana Raymond 1907 ammonite