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: Limopsis conc., conc 1, face and outcrops at 2 separate sites around S end of SSE-trending ridge at SW corner of Long's Ridge, and 7.3 mi W of Whitehorse, Dewey County, South Dakota, USA. Collected by Ian G. Speden, 1962. IP number 350569; lot count 1; taphonomy=concretion; accn=IPA.07048; associatedwith=on same slab: IP.350569,IP.350588,IP.350589,IP.350590,IP.350591,IP.350592,IP.350593,IP.350594,IP.350595,IP.350574,IP.350570,IP.350571,IP.350572,IP.350573,IP.350575,IP.350576,IP.350577,IP.350578,IP.350579,IP.350580,IP.350581,IP.350582,IP.350583,IP.350584,IP.350585,IP.350586,IP.350587.
Yale Peabody Museum’s own description