Where: Japan (35.1° N, 139.9° E: paleocoordinates 39.3° N, 137.5° E)

• coordinate estimated from map

• outcrop-level geographic resolution

When: Aokiyama Formation (Hota Group), Early/Lower Miocene (23.0 - 16.0 Ma)

• The Hota Gp has a thickness of nearly 2000 m and is divided into the Maejima, Takazuru, and Aokiyama Fms in ascending order. The Aokiyama Fm is largely composed of tuff, tuffaceous sandstone, and mudstone. The collection is derived from siltstone in the upper part of the Aokiyama Fm. The age of the unit is considered to be of early Miocene age (18 Ma) on the basis of radiolarian bioostratigraphy (Stichocorys wolffii-Cralocycletta costata zones).

• bed-level stratigraphic resolution

Environment/lithology: deep-water; lithified, gray siltstone

Size class: macrofossils

Collection methods: quarrying,

• Collections housed in IGUT (Institute of Geoscience, University of Tsukuba). Collecting locality no longer exists.

Primary reference: K. Ogasawara, K. Hisada, and N. Kitada. 1994. Early Miocene Calyptogena from the Aokiyama Formation, Hota Group, Boso Peninsula, Japan. Annual Report of the Institute of Geoscience, the University of Tsukuba 20:33-37 [A. Miller/A. Hendy] more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 57692: authorized by Austin Hendy, entered by Austin Hendy on 18.12.2005

Creative Commons license: CC BY-NC-ND (attribution-noncommercial-no derivatives)