Hiraiga Fm Hn 0920b - Tanohata (Cretaceous of Japan)

Where: Iwate, Japan (40.1° N, 141.8° E: paleocoordinates 54.0° N, 140.3° E)

• coordinate estimated from map

• outcrop-level geographic resolution

When: Hiraiga Formation (Miyako Group), Late/Upper Aptian (122.5 - 113.0 Ma)

• Miyako group extends from Aptian - Albian. This collection comes from one of the uppermost Aptian formations in the group. This zone is reported to occur ~10m from the base of the Hiraiga Fm. This collection come from a few cm below collection Hn 920, which is the stratigraphically uppermost collection in the Hiraiga Fm.

• bed-level stratigraphic resolution

Environment/lithology: foreshore; lithified, fine-grained, calcareous sandstone

• reported to be from high-energy, nearshore shallow water env. with clean, cross bedded sandstone. Most crinoid fossils are heavily disarticulated with rare, event derived articulated preservation
• calcareous, fine-grained, well washed (clean) sandstone with large scale cross stratification

Size class: macrofossils

Preservation: original calcite

Collection methods: hydroflouric,

Primary reference: T. Oji. 1985. Early Cretaceous Isocrinus from Northeast Japan. Palaeontology 28(4):629-642 [A. Miller/C. Ferguson]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 65645: authorized by Arnold Miller, entered by Chad Ferguson on 23.09.2006

Creative Commons license: CC BY (attribution)

Taxonomic list

• specimens appear to be stored at University Museum, University of Tokyo
Show authors, comments, and common names
Crinoidea
 Isocrinida - Isocrinidae
Isocrinus (Chladocrinus) hanaii n. sp.
Bivalvia
 Arcida - Glycymerididae
Glycymeris (Hanaia) densilineata
 Carditida - Astartidae
Astarte (Nicaniella) semicostata, Astarte (Trautscholdia) minor