The Ryugase Group is a geological formation on Sakhalin Island in far eastern Russia whose strata date back to the Late Cretaceous.Kawakami Colliery, Sakhalin at Fossilworks.org
Vertebrate paleofauna Nipponosaurus sachalinensis - "Partial skull and associated postcrania, juvenile.""Table 20.1," in Weishampel, et al. (2004). Page 442. Probably actually from the Yezo Group.
See also List of dinosaur-bearing rock formations List of fossiliferous stratigraphic units in Russia
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