Chimeizawa Creek, Haboro area (Cretaceous of Japan)

Where: Japan (44.2° N, 142.0° E: paleocoordinates 48.9° N, 130.5° E)

• coordinate estimated from map

• outcrop-level geographic resolution

When: Nagareya Formation (Yezo Group), Early/Lower Campanian (83.5 - 70.6 Ma)

• Unit Ui-j, the lower part of the Nagareya Formation, mainly consists of mudstone, and its thickness is more than 350 m (Okamoto et al., 2003). Unit Ui-j contains Platyceramus japonicus, indicating the lowermost Campanian (Toshimitsu, 1988; Toshimitsu et al., 1995, 1998; Toshimitsu and Kikawa, 1997; Moriya and Hirano, 2001; Moriya et al., 2001; Okamoto et al., 2003; Toshimitsu et al., 2007). Platyceramus japonicus occurs only from this unit in the Haboro area (Okamoto et al., 2003). Three specimens of Eubostrychoceras described below were obtained from floated calcareous concretions that probably came from this unit (Locality 1 in Figure 1A), judging from co-occurring P. japonicus.

• group of beds-level stratigraphic resolution

Environment/lithology: marine; lithified, concretionary mudstone

Size class: macrofossils

Collection methods: Repository: Mikasa City Museum, Hokkaido

Primary reference: D. Aiba, H. Yamato, K. Kurihara and T. Karasawa. 2017. A new species of Eubostrychoceras (Ammonoidea, Nostoceratidae) from the lower Campanian in the northwestern Pacific realm. Paleontological Research 21:255-264 [M. Clapham/M. Clapham]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 186849: authorized by Matthew Clapham, entered by Matthew Clapham on 05.07.2017

Creative Commons license: CC BY (attribution)

Taxonomic list

 Ammonitida - Nostoceratidae
Eubostrychoceras valdelaxum n. sp. Aiba et al. 2017 ammonite