The Cretaceous Pierre Shale Group in eastern South Dakota and western Wyoming contains numerous fossils, including the flying reptile Pteranodon , 19 specimens of which are described herein. Pteranodon specimens have been found in the two lower formations of the Pierre Shale Group: 4 in the basal Gammon Ferruginous Formation, and 15 in the overlying Sharon Springs Formation. Of these specimens, 64% are associated forelimb elements. Two factors, or a combination thereof, explain the abundance of associated forelimb elements: (1) predatory preference of the muscle mass in the chest over the wing membrane, which may not have offered much nutrient to the predators; and (2) the strong wing membrane, which would have secured the wing elements while the muscle mass would have fallen away. In either case, the wing membrane may have served as a protective layer over the forelimb bones until burial. Two Pteranodon specimens contain vertebrae of the fish Enchodus , which appear to be stomach contents, the first documented Pteranodon stomach contents from South Dakota.