200 m south of Osedani: Langhian, Japan

List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
Chondrichthyes - Torpediniformes - Narcinidae
Benthobatis sp. Alcock 1898
Bivalvia - Protobranchia - Sareptidae
Portlandia sp. Mörch 1857
Bivalvia - Protobranchia - Nuculidae
Ennucula sp. Iredale 1931
see common names

Geography
Country:Japan
Coordinates: 36.6° North, 137.1° East (view map)
Paleocoordinates:36.4° North, 134.6° East (Wright 2013)
Basis of coordinate:stated in text
Geographic resolution:outcrop
Time
Period: Neogene Epoch: Miocene
Stage: Langhian 10 m.y. bin: Cenozoic 5
Key time interval: Langhian
Age range of interval: 15.98 - 13.82 m.y. ago
Stratigraphy
Geological group:Yatsuo Formation:Higashibessho Member:Asatani Siltstone
Stratigraphic resolution:group of beds
Stratigraphy comments: Upper part of the Asatani Siltstone Member of the Higashibessho Formation of the Yatsuo Group. According to Yanagisawa (1999) and Kudo et al. (2011), diatom assemblages from this member are correlated with NPD4A of Yanagisawa and Akiba (1998). They concluded that the Asatani Siltstone Member was deposited around 15.6–15.4 Ma.
Lithology and environment
Primary lithology:massive,tuffaceous,gray,blue lithified carbonaceous mudstone
Lithology description: blue-gray massive tuffaceous mudstones, which included large amounts of coaly matter and several mollusks.
Environment:basinal (siliciclastic)
Geology comments: Molluscan fossils, Ennucula and Portlandia, were collected from the fossil horizon. These two genera correspond to Assemblage 3 of Tsuda (1960) and were collected from the Yatsuo Group in the Kurosedani Formation. The assemblage indicates that the depositional environment was a deep-sea environment.
Taphonomy
Modes of preservation:body
Size of fossils:macrofossils
Collection methods and comments
Reason for describing collection:taxonomic analysis
Collection method comments: Repository: Ujihara Laboratory Specimens Room of the Graduate School of Environmental Studies, Nagoya University
Metadata
Database number:277611
Authorizer:M. Clapham Enterer:M. Clapham
Research group:vertebrate
Created:2026-02-03 12:32:13 Last modified:2026-02-03 12:32:13
Access level:the public Released:0000-00-00 00:00:00
Creative Commons license:
Reference information

Primary reference:
94101. K. Nishimatsu and A. Ujihara. 2017. The first fossil record of the genus Benthobatis (Torpediniformes, Narcinidae) from the Miocene Yatsuo Group of Japan. Palaeoworld 26:699-702 [M. Clapham/M. Clapham]