Sakasegawa Fm - Amakusa (Eocene of Japan)

Where: Japan (32.4° N, 130.2° E: paleocoordinates 39.3° N, 125.4° E)

• coordinate based on nearby landmark

• local area-level geographic resolution

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

• STRATIGRAPHIC RELATIONS: From Sakasegawa Fm, which locally overlies the Late Eocene Itchoda Fm, both of the Sakasegawa Gp. THICKNESS: From formation that attains a thickness of ~1000 m. AGE: Late Eocene, based on molluscan biostratigraphy. STRATIGRAPHIC POSITION: Composite list for the formation in this local area.

• formation-level stratigraphic resolution

Environment/lithology: coastal; lithified siltstone

• ENVIRONMENT: Shallow sea, soft-bottom siliciclastic bottom.
• SPECIFIC LITHOLOGY: Siltstone. LITHIFICATION: Presumed lithified on the basis of age.

Size class: macrofossils

Collection methods: surface (float),

• COLLECTOR: A. Mizuno (c. 1964). REPOSITORY: Not stated in text, unknown.

Primary reference: A. Mizuno. 1964. Paleogene and Early Neogene molluscan faunae in West Japan. Geological Survey of Japan Report 204 [A. Hendy/A. Hendy]more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 70925: authorized by Austin Hendy, entered by Austin Hendy on 11.04.2007

Creative Commons license: CC BY (attribution)

Taxonomic list

• COVERAGE: Exhaustive for gastropoda and bivalvia. NOMENCLATURE: Farly modern nomenclature, and species-level assignments.
Bivalvia
 Pectinida - Propeamussiidae
"Ctenamusium amakusense" = Parvamussium, "Ctenamusium inouei" = Parvamussium
"Ctenamusium amakusense" = Parvamussium mud scallop
"Ctenamusium inouei" = Parvamussium mud scallop
 Pectinida - Limidae
Lima nishiyamai file clam
 Carditida - Crassatellidae
"Crassatellites nipponensis" = Crassatella
"Crassatellites nipponensis" = Crassatella clam
 Carditida - Carditidae
"Venericardia nipponica" = Venericardia (Venericor) nipponica
"Venericardia nipponica" = Venericardia (Venericor) nipponica Yokoyama 1911 clam
 Pholadomyida - Pholadomyidae
"Pholadomya "margaritacea"" = Pholadomya (Bucardiomya) margaritacea
"Pholadomya "margaritacea"" = Pholadomya (Bucardiomya) margaritacea Sowerby 1821 clam
Gastropoda
 Sorbeoconcha - Turritellidae
Orectospira sp. Dall 1925 turret shell