Monzen, Motoyoshi-cho, Miyagi Prefecture: Spathian, Japan

List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
Cephalopoda - Ceratitida - Hemilecanitidae
(1 measurement)
    = Neocolumbites sp. Zacharov 1968
Shigeta and Nakajima 2017
Shigeta 2022
see common names

Geography
Country:Japan
Coordinates: 38.8° North, 141.5° East (view map)
Paleocoordinates:4.9° North, 138.8° East (Wright 2013)
Basis of coordinate:estimated from map
Geographic resolution:small collection
Time
Period: Triassic Epoch: Early Triassic
Stage: Olenekian 10 m.y. bin: Triassic 1
Key time interval: Spathian
Age range of interval: 248.6 - 247 m.y. ago
Stratigraphy
Formation:Hiraiso
Stratigraphic resolution:bed
Stratigraphy comments: Bando (1970) originally considered the age of the Hiraiso Formation to be Griesbachian (early Induan) based on a single ammonoid identified as Glyptophiceras cf. gracile from a floated block of siltstone, which possibly came from the Osawa Formation (Ehiro, 2002). Later, Nakazawa et al. (1994) attributed the specimen to G. aequicostatus and assigned it a late Smithian age. However, our examination of the specimen indicates that it is not G. aequicostatus, and instead should be assigned to the early Spathian ammonoid Neocolumbites Zakharov.
Lithology and environment
Primary lithology: lithified siltstone
Environment:offshore
Taphonomy
Modes of preservation:body
Size of fossils:macrofossils
Collection methods and comments
Collection methods:field collection
Reason for describing collection:taxonomic analysis
Metadata
Database number:101734
Authorizer:M. Clapham Enterer:M. Clapham
Modifier:M. Clapham Research group:marine invertebrate
Created:2010-12-31 15:06:16 Last modified:2025-02-22 15:12:02
Access level:the public Released:2010-12-31 15:06:16
Creative Commons license:CC0
Reference information

Primary reference:
33436. Y. Bando and H. Araki. 1970. On the discovery of Glyptophiceras from the Hiraiso Formation (Lower Triassic) in the Kitakami Massif and a note on the Lower Triassic biostratigraphy. Journal of the Geological Society of Japan 76:165-168 [M. Clapham/M. Clapham]

Secondary references:

33438 Y. Bando. 1970. Lower Triassic ammonoids from the Kitakami Massif. Transactions and Proceedings of the Paleontological Society of Japan, N.S. 79:337-354 [M. Clapham/M. Clapham]
82377 Y. Shigeta. 2022. Revision of early Spathian (late Olenekian, Early Triassic) ammonoids from the Osawa Formation at Akaushi in the Motoyoshi area, South Kitakami Belt, Northeast Japan. Paleontological Research 26:405-419 [M. Clapham/M. Clapham]
61380 Y. Shigeta and Y. Nakajima. 2017. Discovery of the early Spathian (late Olenekian, Early Triassic) ammonoid Tirolites in the Hiraiso Formation, South Kitakami Belt, northeast Japan. Paleontological Research 21:37-43 [M. Clapham/M. Clapham]