Wakkanabi Formation, Ishikari Group - Sorachi district (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: Wakkanabi Formation (Ishikari Group), Lutetian (47.8 - 41.3 Ma)

• STRATIGRAPHIC RELATIONS: From Wakkanabi Fm, which overlies the Yubari and underlies the Bibai Fm, all of the Ishikari Gp (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: marginal marine; lithified siltstone and sandstone

• ENVIRONMENT: Marine and non-marine faunal assemblage.
• SPECIFIC LITHOLOGY: Siltstone and sandstone. 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 70900: 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.
 Ostreida - Ostreidae
Ostrea eorivularis Oyama and Mizuno 1958 oyster
 Ostreida - Pteriidae
"Margaritifera otatumei" = Pinctada, "Margaritifera perdahurica" = Pinctada
"Margaritifera otatumei" = Pinctada pearl oyster
"Margaritifera perdahurica" = Pinctada pearl oyster
 Mytilida - Mytilidae
 Carditida - Crassatellidae
"Crassatellites yessoensis" = Crassatella
"Crassatellites yessoensis" = Crassatella clam
 Carditida - Carditidae
Venericardia otatsumei Uozumi 1955 clam
 Pholadida - Myidae
Mya ezoensis Nagao and Inoue 1941 softshell clam
 Cardiida - Corbiculidae
Corbicula tokudai, "Geloina takaoi" = Polymesoda (Geloina), "Geloina hokkaidoensis" = Polymesoda (Geloina)
"Geloina takaoi" = Polymesoda (Geloina) clam
"Geloina hokkaidoensis" = Polymesoda (Geloina) clam
 Cardiida - Mactridae
Spisula sorachiensis Otatsume 1933 clam
 Cardiida - Veneridae
Pitar sorachiensis Oyama and Mizuno 1958 venus clam
"Microcallista munroei" = Callista (Microcallista) venus clam
Cyclina shirokiana venus clam
 Cardiida - Psammobiidae
 Lucinida - Lucinidae
 Architaenioglossa - Viviparidae
 Neogastropoda - Buccinidae
"Siphonalia" sakakurai Mizuno 1954 true whelk
 Naticoidea - Naticidae
 Calyptraeoidea - Calyptraeidae
Calyptraea sorachiensis Oyama and Mizuno 1958 slipper shell
 Sorbeoconcha - Batillariidae