Where: Japan (42.2° N, 142.7° E: paleocoordinates 47.0° N, 132.1° E)

• coordinate stated in text

• small collection-level geographic resolution

When: Chinomigawa Formation, Middle Campanian (83.5 - 70.6 Ma)

• The Chinomigawa Formation in the Urakawa area was divided into four informal members (U2-U5, Sakai and Kanie, 1986). Member U2 contains Sphenoceramus orientalis (Sokolov, 1914) in the upper part and Member U3 includes S. schmidti (Michael, 1899). Both fossils are index inoceramids of early middle Campanian time in the Northwest Pacific region, an age assignment confirmed by both magnetostratigraphy and zircon geochronology (e.g. Kodama, 1990; Shigeta and Tsutsumi, 2018). Collected from area where members U2 and U3 outcrop, in concretions containing Sphenoceramus orientalis.

• bed-level stratigraphic resolution

Environment/lithology: marine; lithified, concretionary mudstone

Size class: macrofossils

Collected by H. Kubota

Collection methods: surface (float)

• Repository: Hobetsu Museum, Mukawa (HMG)

Primary reference: Y. Shigeta and M. Izukura. 2022. Discovery of the heteromorph ammonoid Amapondella amapondense in the middle Campanian of Hokkaido, Japan. Paleontological Journal 26:369-377 [M. Clapham/M. Clapham]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 226937: authorized by Matthew Clapham, entered by Matthew Clapham on 11.08.2022

Creative Commons license: CC BY (attribution)