Yutaka Bridge: Zanclean, Japan

List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
Osteichthyes - Cetacea - Phocoenidae
2 specimens
see common names

Geography
Country:Japan State/province:Hokkaido County:Numata
Coordinates: 43.8° North, 141.9° East (view map)
Paleocoordinates:43.7° North, 141.0° East (Wright 2013)
Basis of coordinate:stated in text
Time
Period: Neogene Epoch: Pliocene
Stage: Zanclean 10 m.y. bin: Cenozoic 6
Key time interval: Zanclean Other zone:  Thalassiosira oestrupii
Age range of interval: 5.333 - 3.6 m.y. ago
Age estimate: maximum 4.5 ± 0.7 Ma (fission track)
Stratigraphy
Formation:Horokaoshirarika Member:upper
Stratigraphy comments: upper part of the Horokaoshirarika Formation

The age of the upper part of the Horokaoshirarika Formation is about the age of the tuff layer, 4.5 ± 0.7 Ma. Diatoms from the upper part of the Horokaoshirarika Formation correspond to the Thalassiosira oestrupii zone, which shows its age as 5.5 to 3.5 Ma, the late Miocene to the earliest Pliocene (Nakashima and Watanabe, 2000). Following the diatom zonation the age of the upper part of the Horokaoshirarika Formation is about 5.5 to 3.5 Ma, the late Miocene to the earliest Pliocene.
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:taxonomic analysis
Metadata
Database number:125179
Authorizer:M. Uhen Enterer:M. Shalap, M. Uhen
Modifier:P. Wagner Research group:vertebrate
Created:2012-03-06 07:49:58 Last modified:2025-10-29 12:45:01
Access level:the public Released:2012-03-06 07:49:58
Creative Commons license:CC0
Reference information

Primary reference:
58864. Y. Tanaka. 2016. A new and ontogenetically younger specimen of Numataphocoena yamashitai from the upper part of the Horokaoshirarika Formation (lower Pliocene), Numata, Hokkaido, Japan. Paleontological Research 20(2):105-115 [M. Uhen/M. Uhen]

Secondary references:

40624 S. J. Godfrey, L. G. Barnes, and D. J. Bohaska. 2006. Araeodelphis natator Kellogg, 1957, the most primative known member of the Platanistidae (Odontoceti, Cetacea), and relationships to other clades within the Plantanistoidea. Journal of Vertebrate Paleontology 26(3):68 [M. Uhen/M. Shalap/M. Uhen]
61064 Y. Tanaka and H. Ichishima. 2016. A new skull of the fossil porpoise Numataphocoena yamashitai (Cetacea: Phocoenidae) from the upper part of the Horokaoshirarika Formation (lower Pliocene), Numata Town, Hokkaido, Japan, and its phylogenetic position. Palaeontologia Electronica 19.3(49A):1-28 [M. Uhen/M. Uhen]