undet. Bivalvia
From the collection of Yale Peabody Museum. Free to download, adapt and use — no permission needed.
Geological context: Late Cretaceous, Fox Hills Fm, Trail City Mbr. Collection locality: conc. 1, in bench surface, spur of S-facing bluffs, SSE of Maxon ranch house, and .4 mi NE of Maxon ranch reservoir, and 3 mi NW of Little Eagle, Corson County, South Dakota, USA. Collected by Ian G. Speden, 1962. IP number 341906; lot count 1; taphonomy=concretion; accn=IPA.07048; associatedwith=on same slab: IP.341907,IP.341917,IP.341919,IP.341925,IP.341908,IP.341915,IP.341916,IP.341918,IP.341920,IP.341922,IP.341923,IP.341924,IP.341926,IP.341928,IP.341929,IP.341930,IP.341931,IP.341932,IP.341933,IP.341935,IP.341936,IP.341937,IP.341911,IP.341913,IP.341921,IP.341934,IP.341909,IP.341910,IP.341914.
Yale Peabody Museum’s own description