undet. Mollusca
From the collection of Yale Peabody Museum. Free to download, adapt and use — no permission needed.
Geological context: Late Cretaceous, Fox Hills Fm, Iron Lightning Mbr. Collection locality: 2 shell lenses 2 in thick, one 12.5 ft wide and the other, 8 in below, 8 ft wide, about 50 ft [100 ft per KMW] below Hell Creek [probably horizon top of 1st (lower) Colgate, or keybed per KMW], base of Iron Lightning badlands face, 3 mi S of Moreau River, and 4.1 mi SSE of Iron Lightning, Ziebach County, South Dakota, USA. Collected by Ian G. Speden, 1962. IP number 314303; lot count 1; taphonomy=concretion; accn=IPA.07048; associatedwith=IP.314304,IP.314305,IP.314306,IP.314307,IP.314308,IP.314309,IP.314310,IP.314311,IP.314312,IP.314313,IP.314314,IP.314315,IP.314316,IP.314317.
Yale Peabody Museum’s own description