Where: Hiroshima, Japan (34.9° N, 133.0° E: paleocoordinates 38.3° N, 130.2° E)

• coordinate estimated from map

• local area-level geographic resolution

When: lower Member (Itahashi Formation), Burdigalian (20.4 - 16.0 Ma)

• Stratigraphy updated using Tsai 2017

•

•Middle Miocene

•

•The Korematsu Formation in the Shobara area underlies the Itabashi Formation, and together with latter forms the middle/upper portion of the Bihoku Group [114]. Calcareous nannoplankton correlates the Korematsu Formation and the lower part of the Itabashi Formation with the upper part of nannoplankton zone NN4 [114], suggesting a latest Burdigalian or early Langhian age with a minimum of 14.9 Ma [20, 54]. A further study [115] specifically correlated the Korematsu and Itabashi formations exposed along the stretch of the Saijyo River that yielded the whale fossils with the top of nannoplankton zone NN4, and the beginning of the “Mid-Neogene Climatic Optimum” (ca. 16–15 Ma [49, 116]). By contrast, diatom-based biostratigraphic data place the upper part of the Bihoku Group almost entirely in the late Burdigalian (17.0–16.0 Ma) [35, 36, 117, 118]. Together, these estimates amount to an age range of 17.0–14.9 Ma. (Marx & Fordyce, 2015)

• formation-level stratigraphic resolution

Environment/lithology: estuary or bay; sandstone and limestone

Size class: macrofossils

Primary reference: T. Kimura and Y. Hasegawa. 2004. An outline of the Miocene cetotheres of Japan. Bulletin of the Gunma Museum of Natural History 8:79-88 [M. Uhen/M. Uhen]more details

Purpose of describing collection: general faunal/floral analysis

PaleoDB collection 56957: authorized by Mark Uhen, entered by Mark Uhen on 29.11.2005

Creative Commons license: CC BY (attribution)