Mitarai, Shokawa [Mitarai Fm]: Berriasian, Japan

List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
Crinoidea - Isocrinida - Isocrinidae
Chariocrinus japonicus n. sp. Hunter et al. 2011
Bivalvia - Mytilida - Mytilidae
Modiolus sp. (Lamarck 1801)
Bivalvia - Myalinida - Inoceramidae
Inoceramus sp. Sowerby 1814
Cephalopoda - Belemnitida
Belemnitida indet. Zittel 1895
Gastropoda
Gastropoda indet. Cuvier 1795
see common names

Geography
Country:Japan
Coordinates: 36.1° North, 136.9° East (view map)
Paleocoordinates:43.5° North, 139.0° East
Geographic resolution:outcrop
Time
Period:Cretaceous Epoch:Early/Lower Cretaceous
Stage:Berriasian 10 m.y. bin:Cretaceous 1
Key time interval:Berriasian
Age range of interval:145.00000 - 139.80000 m.y. ago
Stratigraphy
Geological group:Tetori Formation:Mitarai
Stratigraphic resolution:bed
Stratigraphy comments: STRATIGRAPHIC RELATIONS: From the Mitarai Fm of the Kuzuryu Subgroup, Tetori Group. AGE: ?Berriasian. The Mitarai Formation was previously assigned to the Middle Jurassic on the basis of a single ammonite species, Lilloetia sp. (Sato and Kanie, 1963), or to the Upper Jurassic by Komatsu et al. (2001) based on bivalves. However, the discovery of new ammonites (berriasellids) and a revision of the formerly described species suggest that the formation is, in fact, Tithonian–Berriasian (Sato et al., 2003). Radiometric U-Pb dating of zircons within tuff beds from the Mitarai Formation give an absolute date of 129.8 ／+ − 1.0 Ma, that is, Hauterivian–Barremian (Kusuhsahi et al., 2006). This data and the recent discovery of a single ammonite, Neocosmoceras sp., that was likely to have been collected from the Mitarai quarry suggests a Berriasian age (Sato et al., 2008), although further evidence is needed to corroborate this determination. STRATIGRAPHIC POSITION: The crinoid remains are from the uppermost layer within a black sandy shale and occur with a rich associated fauna of bivalves (Inoceramus sp., Modiolus sp.), gastropods, belemnites and plant remains (Nomura, 1969).
Lithology and environment
Primary lithology:black lithified sandy "shale"
Includes fossils?Y
Lithology description: SPECIFIC LITHOLOGY: Black sandy shale. LITHIFICATION: Lithified, on the basis of figured specimens.
Environment:offshore
Taphonomy
Modes of preservation:body
Size of fossils:macrofossils,mesofossils
Collection methods and comments
Collection excludes:some macrofossils
Collection methods:bulk,surface (in situ),survey of museum collection
Reason for describing collection:taxonomic analysis
Collection method comments: COLLECTOR: Not stated in text. REPOSITORY: University Museum, University of Tokyo (UMUT-ME).
Taxonomic list comments:COVERAGE: Limited to crinoid described in manuscript and other characteristic macro invertebrates.
Metadata
Database number:161967
Authorizer:A. Hendy Enterer:A. Hendy
Research group:marine invertebrate
Created:2014-09-16 16:28:21 Last modified:2014-09-16 16:28:21
Access level:the public Released:2014-09-16 16:28:21
Creative Commons license:CC BY
Reference information

Primary reference:
52764. A. W. Hunter, T. Oji, T. M. Ewin and K. Kitazawa. 2011. Chariocrinus japonicus, a new species of isocrinid crinoid (Articulata) from the Lower Cretaceous of Takayama City, central Japan. Bulletin of the Mizunami Fossil Museum (37)115-121 [A. Hendy/A. Hendy]