Usui River: Tortonian, Japan

List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
Osteichthyes - Anseriformes - Anatidae
Matsuoka and Hasegawa 2022 1 specimen
GMNH-PV-678
Osteichthyes - Perissodactyla - Paleoparadoxiidae
Hasegawa and Kimura 2008
Nakajima specimen
Osteichthyes - Cetacea - Lipotidae
Kimura and Hasegawa 2024 1 specimen
GMNH-PV-1011
Osteichthyes - Cetacea - Kentriodontidae
6 specimens
Osteichthyes - Cetacea - Delphinidae
Kimura and Hasegawa 2020 2 specimens
GMNH-PV-3463, GMNH-PV-3464
Osteichthyes - Cetacea
Kimura and Hasegawa 2019 1 specimen
see common names

Geography
Country:Japan State/province:Gunma County:Annaka
Coordinates: 36.3° North, 138.9° East (view map)
Paleocoordinates:35.9° North, 137.1° East (Wright 2013)
Basis of coordinate:stated in text
Time
Period: Neogene Epoch: Miocene
Stage: Tortonian 10 m.y. bin: Cenozoic 6
Key time interval: Tortonian
Age range of interval: 11.63 - 7.246 m.y. ago
Stratigraphy
Geological group:Annaka Formation:Haraichi
Stratigraphy comments: Haraichi Formation, Annaka Group, latest middle/earliest late Miocene, Serravallian/Tortonian (ca. 11.5 Ma). The Haraichi Formation includes several tuff layers (Takahashi and Hayashi, 2004). The specimen was found in the horizon located stratigraphically between the Kitamura and Baba tuffs. 40Ar/39Ar dating of the tuffs yielded geological ages of 11.79 ± 0.08 Ma (biotite) for the Kitamura tuff and 11.26±0.09 Ma (biotite) and 11.29 ± 0.12 Ma (sanidine) for the Baba tuff (Odin et al., 1997).
Lithology and environment
Primary lithology: not reported
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
Also known as:Nakahashi Bridge
Database number:200052
Authorizer:M. Uhen Enterer:M. Uhen
Modifier:M. Uhen Research group:vertebrate
Created:2019-03-04 09:34:27 Last modified:2025-02-22 15:12:02
Access level:the public Released:2019-03-04 09:34:27
Creative Commons license:CC0
Reference information

Primary reference:
25731. T. Kimura and Y. Hasegawa. 2019. A new species of Kentriodon (Cetacea, Odontoceti, Kentriodontidae) from the Miocene of Japan. Journal of Vertebrate Paleontology 1-93 [M. Uhen/M. Uhen/M. Uhen]

Secondary references:

37937 Y. Hasegawa and T. Kimura. 2008. On the two large specimens of Paleoparadoxia (Middle Miocene) from Western Gunma Prefecture, Japan. Bulletin of the Gunma Museum of Natural History 12:15-33 [M. Uhen/M. Uhen]
93353 T. Kimura and Y. Hasegawa. 2019. New specimen of Joumocetus shimizui from the Miocene Haraichi Formation, Annaka Group, Gunma Prefecture, Japan. Bulletin of the Gunma Museum of Natural History 23:13-20 [M. Uhen/M. Uhen]
72982 T. Kimura and Y. Hasegawa. 2020. Norisdelphis annakaensis, a new Miocene delphinid from Japan. Journal of Vertebrate Paleontology e1762628 [M. Uhen/M. Uhen]
91876 T. Kimura and Y. Hasegawa. 2021. Second report on the new material of Joumocetus shimizui from the Miocene Haraichi Formation, Annaka Group, Gunma, Japan. Bulletin of the Gunma Museum of Natural History 25:59-64 [M. Uhen/M. Uhen]
87976 T. Kimura and Y. Hasegawa. 2024. New fossil lipotid (Cetacea, Delphinida) from the Upper Miocene of Japan. Paleontological Research 28(4):1-23 [M. Uhen/M. Uhen]
70723 K. Matsui and T. Tsuihiji. 2019. The phylogeny of desmostylians revisited: proposal of new clades based on robust phylogenetic hypotheses. PeerJ 7:e7430 [M. Uhen/M. Uhen]
82041 H. Matsuoka and Y. Hasegawa. 2022. Annakacygna, a new genus for two remarkable flightless swans (Aves, Anatidae, Cygnini) from the Miocene of Gunma, central Japan: With a note on the birds’food niche shift and specialization of wings for parental care actions. Bulletin of the Gunma Museum of Natural History 26:1-30 [M. Uhen/M. Uhen/M. Uhen]