Retort Phosphatic Shale Member, Phosphoria Formation of Montana (Permian of the United States)

Where: Montana (47.1° N, 109.4° W: paleocoordinates 17.6° N, 29.8° W)

• coordinate based on political unit

• basin-level geographic resolution

When: Retort Phosphatic Shale Member (Phosphoria Formation), Lopingian (259.9 - 252.2 Ma)

• Davydov et al. 2017 dated an ash bed in the upper Meade Peak Member at 260.57 ± 0.07 / 0.14 / 0.31 Ma, indicating that the Meade Peak is as young as uppermost Capitanian.

• member-level stratigraphic resolution

Environment/lithology: marine; phosphatic claystone and black limestone

• Fossils bearing shale beds are rare indicating an extremely oxygen poor environment for most of the deposition of the Retort.
• phosphatic claystone and dark, fine grained limestone

Size class: macrofossils

Primary reference: E. L. Yochelson and D. H. Van Sickle. 1968. Biostratigraphy of the Phosphoria, Park City, and Shedhorn Formations; Geology of Permian Rocks in the Western Phosphate Field. United States Geological Survey Professional Paper 313(D):572-660 [A. Miller/C. Ferguson/P. Wagner]more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 11275: authorized by Arnold Miller, entered by Chad Ferguson on 30.07.2001

Creative Commons license: CC BY (attribution)

Taxonomic list

• P. albequus, P. canna, E. crenulatus, B. deflectus, and K. (R.) eximia found in a sandstone matrix. They are thought to be from the Lower Member of the Shedhorn Formation instead of Retort.
Show authors, comments, and common names
unclassified
  -
Amonoidea indet.
Bivalvia
 Cardiida - Kalenteridae
Permophorus albequus
Permophorus albequus Beede 1907 clam
 Trigoniida - Schizodidae
Schizodus sp.
Schizodus sp. King 1844 clam
 Pectinida - Streblochondriidae
Streblochondria sp.
Streblochondria sp. Newell 1938 scallop
 Nuculida - Nuculidae
Nuculopsis sp.
Nuculopsis sp. Girty 1912 nut clam
Scaphopoda
 Dentaliida - Prodentaliidae
"Plagioglypta canna" = Prodentalium canna
"Plagioglypta canna" = Prodentalium canna White 1874 tusk shell
Gastropoda
 Murchisoniina - Phymatopleuridae
? Worthenia sp.
? Worthenia sp. de Koninck 1883 snail
 Euomphalina - Omphalotrochidae
Babylonites sp.
Babylonites sp. Yochelson 1956 snail
 Bellerophontida - Euphemitidae
Euphemites crenulatus
Euphemites crenulatus Yochelson 1960 snail
 Bellerophontida - Bellerophontidae
Bellerophon deflectus, "Knightites (Retispira) eximia" = Yochelsonellisa eximia
Bellerophon deflectus Chronic 1952 snail
"Knightites (Retispira) eximia" = Yochelsonellisa eximia Yochelson 1960 snail
Cephalopoda
 Goniatitida - Paragastrioceratidae
Pseudogastrioceras sp.
Pseudogastrioceras sp. Spath 1936 ammonite
 Belemnoidea -
Belemnitida indet.
Belemnitida indet. Zittel 1895 belemnite
Lingulata
 Lingulida - Discinidae
Orbiculoidea sp., Orbiculoidea (Orbiculoidea) cf. missouriensis
Orbiculoidea sp. d'Orbigny 1847
Strophomenata
 Strophomenida - Rugosochonetidae
"Chonetes cf. ostiolatus" = Komiella ostiolata
"Chonetes cf. ostiolatus" = Komiella ostiolata Girty 1910
Gnathostomata
  -
Osteichthyes indet.