Sakasagawa Fm - Haboro coal field, Hokkaido (Eocene of Japan)

Where: Japan (44.4° N, 141.7° E: paleocoordinates 46.6° N, 138.0° E)

• coordinate based on nearby landmark

• local area-level geographic resolution

When: Sakasagawa Formation, Late/Upper Eocene (37.2 - 33.9 Ma)

• STRATIGRAPHIC RELATIONS: From "Sakasagawa" Fm , which unconformably overlies the Sankebetsu Fm (Ealry Miocene) and unconformably overlies the Early Eocene Haboro Fm. THICKNESS: Unknown thickness of unit. AGE: Late Eocene on the basis of molluscan biostratigraphy. STRATIGRAPHIC POSITION: Collection a composite list for entire formation.

• formation-level stratigraphic resolution

Environment/lithology: coastal; lithified sandstone

• ENVIRONMENT: coastal siliciclastic environment.
• SPECIFIC LITHOLOGY: Sandstone/ LITHIFICATION: Presumably lithified, on the basis of age.

Size class: macrofossils

Collection methods: COLLECTOR: Based on previous collectors (see Noda 1992, 1995). REPOSITORY: Unknown repository.

Primary reference: A. I. Kafanov, K. Ogasawara, and Y. Noda. 2005. Cenozoic molluscan (Bivavia) cenozone of Hokkaido, Northern Japan. Science Report, Institute of Geosciences, Univeristry of Tsukuba 26:1-12 [A. Hendy/A. Hendy/A. Hendy]more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 70424: authorized by Austin Hendy, entered by Austin Hendy on 22.03.2007

Creative Commons license: CC BY (attribution)

Taxonomic list

• COVERAGE: Only includes characteristic bivalvia; other taxa not listed, possibly reported in Noda (1992, 1995). NOMENCLATURE: Not an authoritative publication, but with very current nomenclature and subgenus/species resolution identifications.
Bivalvia
 Lucinida - Thyasiridae
Conchocele bisecta Conrad 1849 clam
 Thraciida - Periplomatidae
 Pholadida - Myidae
Mya convexa Noda 1992 softshell clam
"Mya salmonensis" = Mya (Mya) salmonensis Clark 1932 softshell clam
Mya (Mya) truncata Linnaeus 1758 softshell clam
 Cardiida - Veneridae
 Cardiida - Cardiidae
 Carditida - Carditidae
 Nuculida - Nuculidae
Acila (Acila) brevis Nagao and Huzioka 1941 divaricate nutclam
 Nuculanida - Nuculanidae
Yoldia (Orthoyoldia) haboroensis Uozumi 1957 pointed nut clam
 Nuculanida - Yoldiidae
Yoldia (Yoldia) biremis Uozumi 1957 clam