undet. Bivalvia
From the collection of Yale Peabody Museum. Free to download, adapt and use — no permission needed.
Geological context: Late Cretaceous, Meeteetse Fm. Collection locality: upper Meeteetse, near "gasline gap", SE of Hatcher Pass, & W of Cottonwood Creek, & W of Wade, Carbon County, Montana, USA. Collected by Jason F. Hicks, 1988. IP number 86769; lot count 1; taphonomy=concretion; accn=IPA.07531; associatedwith=on same slab: IP.086769,IP.617098,IP.617099,IP.617100,IP.617101,IP.617102,IP.617103,IP.617104,IP.617105,IP.617106,IP.617107,IP.617108,IP.617109,IP.617110,IP.617111,IP.617112,IP.617113,IP.617114,IP.617115,IP.617116,IP.617117,IP.617118,IP.617119,IP.617120,IP.617121,IP.617122,IP.617123,IP.617124,IP.617126,IP.617127,IP.617128,IP.617129,IP.617131,IP.617135,IP.617136,IP.617125,IP.617130,IP.617132,IP.617133,IP.617134.
Yale Peabody Museum’s own description