OM-2 - Omagari Formation, Tokomuro district (Oligocene of Japan)

Where: Japan (42.8° N, 143.7° E: paleocoordinates 44.1° N, 141.3° E)

• coordinate based on nearby landmark

• small collection-level geographic resolution

When: Omagari Formation, Late/Upper Oligocene (28.4 - 23.0 Ma)

• STRATIGRAPHIC RELATIONS: From Omagari Fm of the Ombetsu Gp, which overlies the Shakubetsu Fm of the Urahaoro Gp (Early Oligocene) and is overlain by the Charo Fm of the Ombetsu Gp (Late Oligocene). THICKNESS: From bed with unit 60-160 m thick. AGE: Late Oligocene based on molluscan biostratigraphy. STRATIGRAPHIC POSITION: Unknown position within formation.

• bed-level stratigraphic resolution

Environment/lithology: coastal; lithified, conglomeratic sandstone

• ENVIRONMENT: Coastal marine, siliciclastic environment.
• SPECIFIC LITHOLOGY: Conglomerate sandstone. LITHIFICATION: Assumed to be lithifed on the basis of figured specimens and age.

Size class: macrofossils

Collection methods: COLLECTOR: Presumably S. Yui (c. 1975). REPOSITORY: Probably Tohoku University, Japan.

Primary reference: Y. Honda. 1989. Paleogene molluscan faunas from the Kushiro Coal Field, Eastern Hokkaido. Tohoku University, Science Report, 2nd series 60(1):1-137 [A. Hendy/A. Hendy]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 70600: authorized by Austin Hendy, entered by Austin Hendy on 29.03.2007

Creative Commons license: CC BY (attribution)

Taxonomic list

• COVERAGE: Exhaustive for gastropoda, bivalvia and scaphopoda. NOMENCLATURE: Authoritative publication, using moderately recent nomenclature, subgenus and species level designations.
Gastropoda
 Cerithioidea - Turritellidae
 Neogastropoda - Buccinidae
"Neptunea ezoana" = Trominina ezoana
"Neptunea ezoana" = Trominina ezoana Takeda 1953 true whelk
 Neogastropoda - Fasciolariidae
Bivalvia
 Cardiida - Cardiidae
 Carditida - Carditidae
 Nuculanida - Yoldiidae
 Nuculanida - Sareptidae
Scaphopoda
 Dentaliida - Dentaliidae
Dentalium sp. Linnaeus 1758 tusk shell