75 m. Eastern slope of Memaruyama, along the valley of the Naidaijin River: Late Givetian, Japan

List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
Artiopoda - Corynexochida - Styginidae
Artiopoda - Phacopida - Phacopidae
see common names

Geography
Country:Japan
Coordinates: 32.6° North, 131.0° East (view map)
Paleocoordinates:
Basis of coordinate:stated in text
Geographic resolution:outcrop
Time
Period: Devonian Epoch: Late Devonian
Stage: Frasnian
Key time interval: Late Givetian
Age range of interval: 383.4 - 382.31 m.y. ago
Age estimate: 383.9 ± 4.4 Ma (U/Pb)
Stratigraphy
Formation:Naidaijin Member:Lower
Local section:Eastern slope of Memaruyama Local bed:75 m
Local order:bottom to top
Stratigraphic resolution:bed
Stratigraphy comments: detrital zircons dated 2 m above this horizon.
Lithology and environment
Primary lithology: sandy mudstone
Lithology description: Within the Lower Member of the Naidaijin Formation, the trilobite-bearing horizon is a sandy mudstone (Figure 3) in a succession rich in volcaniclastic material, tuffaceous sandstones and mudstones. Marine fossils including brachiopods, pelmatozoan debris and ostracods cooccur with the trilobites, and pelmatozoan debris also occurs in adjacent mudstones (Figure 2). The trilobites occur as non-fragmented detached cephala and pygidia as well as thoracopyga. The disarticulated nature of many of the fossils suggests a thanatocoenosis, though it is not clear how far the material has been transported. Alternatively the disarticulated trilobite sclerites could indicate exuviae. However, there is insufficient material to confirm either hypothesis.
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:223346
Authorizer:P. Wagner Enterer:P. Wagner
Research group:marine invertebrate
Created:2021-11-08 20:59:30 Last modified:2025-02-22 15:12:02
Access level:the public Released:2021-11-08 20:59:30
Creative Commons license:CC0
Reference information

Primary reference:
78549. C. Stocker, G. Tanaka, D. J. Siveter, P. Lane, Y. Tsutsumi, To Komatsu, S. Wallis, T. Oji, D. J. Siveter and M. Williams. 2018. Biogeographical and Biostratigraphical Significance of a New Middle Devonian Phacopid Trilobite from the Naidaijin Formation, Kurosegawa Terrane, Kyushu, Southwest Japan. Paleontological Research 22(1):75-90 [P. Wagner/P. Wagner]