Chikubetsu: Aquitanian, Japan

List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
Mammalia - Perissodactyla - Paleoparadoxiidae
Paleoparadoxia sp. Reinhart 1959
3 specimens
see common names

Geography
Country:Japan State/province:Hokkaido
Coordinates: 44.4° North, 141.9° East (view map)
Paleocoordinates:45.3° North, 139.8° East
Basis of coordinate:stated in text
Time
Period:Neogene Epoch:Miocene
Stage:Aquitanian 10 m.y. bin:Cenozoic 5
Key time interval:Aquitanian
Age range of interval:23.03000 - 20.44000 m.y. ago
Stratigraphy
Formation:Sankebetsu
Stratigraphic resolution:formation
Stratigraphy comments: The age of the Sankebetsu Formation was estimated based on fission-track (FT) dating, marine molluscs, and diatom fossils (Kurita et al., 1992; Noda, 1992; Kafanov et al., 2005). FT ages for the upper part and base of the formation were reported as 20.6±1.0 Ma and 23.8±1.5 Ma, respectively (Kurita et al., 1992). The molluscan fauna (e.g. Mytilus tichanovitchi, Macoma osakaensis, Megayoldia (Hataiyoldia) tokunagai, and Neilonella (Borissia) sakhalinensis) indicates that the formation was deposited in the early Miocene (Kafanov et al., 2005). The diatoms indicate ages from 24.0 Ma to 20.3 Ma (Thalassiosira praefraga zone; Hata et al., 1988; Kurita et al., 1992), consistent with the FT ages. The locality of the present specimen is more upstream than the sampling point for the FT analysis. The float’s age is likely older than the FT ages, as the ages of strata become older upstream in this area. In conclusion, the possible age of the present specimen can be constrained between 25.3 Ma (oldest estimate based on FT, including the possible error of 20.6±1.0) and 20.3 Ma (youngest estimate based on diatoms).
Lithology and environment
Primary lithology:gray sandstone
Includes fossils?Y
Lithology description: The Sankebetsu Formation consists of massive, tuffaceous, fine- to medium- grained gray sandstone.
Environment:marine indet.
Taphonomy
Modes of preservation:body
Size of fossils:macrofossils
Collection methods and comments
Reason for describing collection:general faunal/floral analysis
Metadata
Database number:171611
Authorizer:M. Uhen Enterer:M. Uhen
Research group:vertebrate
Created:2015-07-14 13:04:10 Last modified:2015-07-14 13:04:10
Access level:the public Released:2015-07-14 13:04:10
Creative Commons license:CC BY
Reference information

Primary reference:
55797. K. Matsui and S. Kawabe. 2015. The Oldest Record of Paleoparadoxia from the Northwest Pacific with an Implication on the Early Evolution of Paleoparadoxiinae (Mammalia: Desmostylia). Paleontological Research 19(3):251-265 [M. Uhen/M. Uhen]