Yubari Formation, Ishikari Group (Eocene of Japan)

Where: Japan (43.5° N, 142.0° E: paleocoordinates 46.7° N, 136.4° E)

• coordinate based on nearby landmark

• local area-level geographic resolution

When: Yubari Formation (Ishikari Group), Lutetian (47.8 - 41.3 Ma)

• STRATIGRAPHIC RELATIONS: From Yubari Fm, which overlies the Horokabetsu and underlies the Wakkanabe Fm, all of the Ishikari Gp (early Middle Eocene). THICKNESS: From unit which reaches a thickness of 100-250 m. AGE: early Middle Eocene according to Takano and Waseda (2003). Referred only to Eocene in Mizuno (1964). STRATIGRAPHIC POSITION: Composite checklist for formation from local area.

• formation-level stratigraphic resolution

Environment/lithology: fluvial; lithified siltstone

• ENVIRONMENT: Contains freshwater shells.
• SPECIFIC LITHOLOGY: Sandstone and siltstone. LITHIFICATION: Assume to be lithified on the basis of age and photgraphic plates of Takano and Osamu (2003).

Size class: macrofossils

Preservation: cast, mold/impression

Collection methods: COLLECTOR: T. Mizuno (c. 1960's). REPOSITORY: Unknown, not stated in text.

Primary reference: A. Mizuno. 1964. Summary of the Paleogene molluscan faunas in North Japan. Geological Survey of Japan Report 207 [A. Hendy/A. Hendy/A. Hendy]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 70899: authorized by Austin Hendy, entered by Austin Hendy on 11.04.2007

Creative Commons license: CC BY (attribution)

Taxonomic list

• COVERAGE: Exhaustive for bivalvia and gastropoda. NOMENCLATURE: Somewhat antiquated, but with species-level identifications.
Show authors, comments, and common names
unclassified
  -
Lanceolaria pisciformis, Lepidodesma septemtrionale
Bivalvia
 Ostreida - Pteriidae
"Margaritifera ? otatumei" = Pinctada, "Margaritifera perdahurica" = Pinctada
"Margaritifera ? otatumei" = Pinctada pearl oyster
"Margaritifera perdahurica" = Pinctada pearl oyster
 Cardiida - Corbiculidae
Corbicula ? tokudai