抄録
Very small, stereotyped drill holes are found in 15 shells of Kotorapecten egregius (Itoigawa), collected from the lower Miocene Akeyo Formation (ca. 18 Ma) of the Mizunami Group in Mizunami City, Gifu, central Japan based upon the examination of the collection of Mizunami Fossil Museum. These drill holes can be assigned to the ichnotaxon Oichnus ovalis Bromley, attributed to predation by octopods. These examples are the oldest ambiguous fossil records of the octopod-predatory drill holes found in Japan.
https://ror.org/0375k5p31 
