Shakubetsu Fm - Kushiro Coal Field (Oligocene of Japan)

Where: Japan (43.0° N, 144.4° E: paleocoordinates 44.8° N, 141.7° E)

• coordinate based on nearby landmark

• local area-level geographic resolution

When: Shakubetsu Formation (Urahoro Group), Early/Lower Oligocene (33.9 - 28.4 Ma)

• STRATIGRAPHIC RELATIONS: Uppermost unit of the Urahoro Group, lying between the Shitakara Fm (Early Oligocene) and the Omagari Formation of the Ombetsu Group (presumably Late Oligocene). THICKNESS: Unknown thickness of unit. AGE: Presumably Early Oligocene; from near base of Oligocene in region. STRATIGRAPHIC POSITION: Collection representative of entire formation in local area.

• formation-level stratigraphic resolution

Environment/lithology: marginal marine; lithified, fine-grained, pebbly, gray, conglomeratic, carbonaceous sandstone

• ENVIRONMENT: Non-marine through shallow marine.
• SPECIFIC LITHOLOGY: Gray, poorly sorted, fine-grained sandstone and pebbly to granular conglomerate composed of chert pebbles, with intercalated coal seams. LITHIFICATION: Presumed lithified, on the basis of age, presence of coal, and low diversity of fauna.

Size class: macrofossils

Collection methods: COLLECTOR: Unknown collected, possibly Y. Honda. REPOSITORY: Unknown repository.

Primary reference: Y. Honda. 1986. A Paleogene molluscan fauna from Hokkaido, northern Japan. Paleontological Society of Japan Special Papers 29:3-15 [A. Hendy/A. Hendy]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 68895: authorized by Austin Hendy, entered by Austin Hendy on 12.02.2007

Creative Commons license: CC BY (attribution)

Taxonomic list

• COMPLETENESS: Authoritative for Mollusca. NOMENCLATURE: Slightly antiquated, but with consistent use of species level and subgeneric assignments.
Semisulcospira fiscina
SUBSPECIES: S. fiscina yokoyamai
 Ostreida - Ostreidae
Ostrea eorivularis Oyama and Mizuno 1958 oyster
 Ostreida - Pteriidae
"Margaritifera sp." = Pinctada
"Margaritifera sp." = Pinctada RÅ¡ding 1798 pearl oyster
 Mytilida - Mytilidae
Mytilus sp. Linnaeus 1758 mussel
Mytilus mabuchii Oyama and Mizuno 1958 mussel
Mytilus cf. luciferus Yokoyama 1924 mussel
Modiolus sp. Lamarck 1801 mussel
 Cardiida - Corbiculidae
 Cardiida - Cardiidae
Nemocardium sp. Meek 1876 cockle
 Unionida - Unionidae
Anodonta subjapanensis freshwater mussel
SUBSPECIES: A. subjapanensis yokoymau
 Architaenioglossa - Viviparidae
 Naticoidea - Naticidae
Neverita (Neverita) sp. Risso 1826 moon snail
 Sorbeoconcha - Potamididae
 Sorbeoconcha - Thiaridae
? Melanoides sp. Olivier 1804 snail