Iwaki amber, Kobisa River: Late Coniacian, Japan

List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
Insecta - Blattodea - Ectobiidae
Aiba and Oyama 2026 1 specimen
FM-N202200014
Insecta - Hymenoptera - Mymarommatidae
3 specimens
FM-N202200057, 00062, 00015 (4 measurements)
see common names

Geography
Country:Japan
Coordinates: 37.1° North, 141.0° East (view map)
Paleocoordinates:45.2° North, 141.1° East (Wright 2013)
Basis of coordinate:estimated from map
Geographic resolution:outcrop
Time
Period: Cretaceous Epoch: Late Cretaceous
Stage: Coniacian 10 m.y. bin: Cretaceous 6
Key time interval: Late Coniacian
Age range of interval: 89.8 - 85.7 m.y. ago
Stratigraphy
Geological group:Futaba Formation:Tamayama Member:Kohisagawa
Stratigraphic resolution:group of beds
Stratigraphy comments: The fossil-bearing amber was obtained from the blackish sandstone of the Kohisagawa Member of the Tamayama Formation. The upper part of the Tamayama Formation, the Irimazawa Member, is a shallow marine deposit that is considered to be late Coniacian to early Santonian from the Inoceramus mihoensis zone to Inoceramus amakusensis zone (Obata and Suzuki, 1969). The Kasamatsu Formation below the Kohisagawa Member has not yielded any significant fossils that can be dated, but Matsumoto et al. (1982) considered it to be upper Coniacian. Furthermore, ammonite fossils have been recovered from the lower part of the underlying Ashizawa Formation, Obisagawa Member, which has been dated to the Early to Middle Coniacian (Matsumoto et al., 1990; Kubo et al., 2002). Therefore, it is reasonable to consider the age of the Kohisagawa Member of the Tamayama Formation, which bears fossil amber, to be Late Coniacian (Saegusa and Tomida, 2011).
Lithology and environment
Primary lithology: amber
Environment:terrestrial indet.
Taphonomy
Modes of preservation:body,amber
Size of fossils:macrofossils,mesofossils
Collection methods and comments
Reason for describing collection:taxonomic analysis
Collection method comments: Repository: Fukushima Museum, Fukushima Prefecture, Japan
Metadata
Database number:236006
Authorizer:M. Clapham Enterer:M. Clapham
Modifier:M. Clapham Research group:paleoentomology
Created:2024-09-07 20:28:01 Last modified:2025-03-19 13:07:15
Access level:the public Released:2024-09-07 20:28:01
Creative Commons license:CC0
Reference information

Primary reference:
89359. H. Aiba and H. Inose. 2024. A new false fairy wasp (Hymenoptera: Mymarommatoidea: Mymarommatidae) in Late Cretaceous Iwaki amber from Futaba Group of Iwaki City, Fukushima Prefecture, Japan. Paleontological Research 28:337-344 [M. Clapham/M. Clapham]

Secondary references:

95197 H. Aiba and N. Oyama. 2026. Early evolution of nocturnal behavior in cockroaches documented by a new Coniacian (Late Cretaceous) amber fossil from Japan. Paleontological Research 30:99-108 [M. Clapham/M. Clapham]