Mokawaruppu River: Late Maastrichtian, Japan

List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
Cephalopoda - Ammonitida - Diplomoceratidae
see common names

Geography
Country:Japan
Coordinates: 43.1° North, 143.7° East (view map)
Paleocoordinates:48.0° North, 135.3° East (Wright 2013)
Basis of coordinate:estimated from map
Geographic resolution:outcrop
Time
Period: Cretaceous Epoch: Late Cretaceous
Stage: Maastrichtian 10 m.y. bin: Cretaceous 8
Key time interval: Late Maastrichtian Foram zone:  Abathomphalus mayaroensis
Age range of interval: 72.2 - 66 m.y. ago
Stratigraphy
Formation:Kawaruppu
Stratigraphic resolution:bed
Stratigraphy comments: Diplomoceras cylindraceum, reported here, was extracted from a siltstone 15 m below the K/Pg boundary. Magnetostratigraphy at this site indicates that the base of C30r is situated 45 m below the K/Pg boundary (Hamano et al., 1986; Hamano, 1988; Kaiho, 1992). Using the time scale of Ogg (2012) for the geomagnetical polarity and Vandenberghe et al. (2012) for the K/Pg boundary, the age of the base of C30r is 68.369 Ma, and the age of the K/Pg boundary is 66.0 Ma. Supposing that the sediment accumulation rate is constant based on the monotonous siltstone throughout the sequence, the age of the fossil horizon is estimated to be ~66.8 Ma. D. cylindraceum, therefore, lived to at least ~0.8 m.y. before the K/Pg boundary event in the north Pacific region.
Lithology and environment
Primary lithology: lithified siltstone
Environment:marine indet.
Taphonomy
Modes of preservation:body
Size of fossils:macrofossils
Collection methods and comments
Reason for describing collection:taxonomic analysis
Collection method comments: Repository: Historical Museum of Urahoro, Hokkaido, Japan
Metadata
Database number:177752
Authorizer:M. Clapham Enterer:M. Clapham
Research group:marine invertebrate
Created:2016-04-09 22:57:58 Last modified:2025-02-22 15:12:02
Access level:the public Released:2016-04-09 22:57:58
Creative Commons license:CC0
Reference information

Primary reference:
58825. K. Kurihara, M. Kano, H. Sawamura and Y. Sato. 2016. The last surviving ammonoid at the end of the Cretaceous in the north Pacific region. Paleontological Research 20:116-120 [M. Clapham/M. Clapham]