Threeforks Shale, Jefferson Island Co., Montana (measured section 4 of author) (Devonian of the United States)

Where: Jefferson Island County, Montana (45.9° N, 111.9° W: paleocoordinates 14.8° S, 46.6° W)

• coordinate based on nearby landmark

• 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; yellow shale and siltstone

• 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. this collection came from the lower shale, which is described as variegated in color (reds, yellow, brown) and finely laminated, and the upper shales from a horizon identified as a siltstone

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 6979: 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
Strophomenata
 Orthotetida - Schuchertellidae
Schuchertella sp.
Schuchertella sp. Girty 1904
Rhynchonellata
 Orthida - Rhipidomellidae
Rhipidomella cf. newalbanensis
Rhipidomella cf. newalbanensis
Rhipidomella cf. vanuxemi newalbanensis
 Spiriferinida - Syringothyrididae
Syringothyris cf. typus
Craniata
 Craniida - Craniidae
Petrocrania sp.
Petrocrania sp. Raymond 1910