Jackknife clam (Patinopecten)
Yobake cliff
Shimo-Ogano, Ogano city, Chichibu county, Saitama pref., Japan
Middle Miocene, Neogene, Cenozoic (15 Ma)
Width: 100 mm. Fossil of Jackknife clam (Patinopecten) recovered from sandstone of the Middle Miocene (16 Ma) Nagura Formation in the Chichibumachi Group formed under the marine environment such as submarine fans.