Abstract Although a diverse range of aquatic vertebrates are documented from the Upper Cretaceous (mid-Campanian) marine strata of the Kristianstad Basin in southern Sweden, only chondrichthyans and marine amniotes have been described in detail to date. In contrast, coeval actinopterygians are virtually unreported, yet their remains are extremely abundant at most sampled localities. A comprehensive assessment of these fossils has identified the first Late Cretaceous actinopterygian fauna from the Fennoscandian Shield, incorporating indeterminate lepisosteids, the durophagous pycnodontid Anomoeodus subclavatus , the predatory pachycormid Protosphyraena sp., a large ichthyodectid, pachyrhizodontids resembling Pachyrhizodus , the enchodontid Enchodus cf. gladiolus and indeterminate small teleosts. These taxa are diagnosed mainly from isolated teeth and scales, implying substantial taphonomic loss prior to burial. Moreover, the prolific recovery of actinopterygian skeletal remnants in recent excavations suggests that historical collecting biases, rather than ecological paucity, have contributed to their under-representation in the Swedish Cretaceous record. Palaeobiogeographically, the Kristianstad Basin actinopterygians show compositional resemblance to assemblages from the Northern European Platform and the Western Interior Seaway of North America, advocating distributional communication across the Boreal proto-Atlantic Ocean.

The osteichthyan paleofauna of the upper Pierre Shale Group has yielded range extensions for taxa known from its Sharon Springs Formation and the underlying Niobrara Formation, notably with the genera Protosphyraena and Pachyrhizodus . Links are now more apparent with Campanian and Maastrichtian (Late Cretaceous) paleofaunas from the Atlantic and Gulf Coasts of the United States, as with Cylindracanthus and Enchodus . Common elements are to be expected, considering the similarities in their geologic ages and environments of deposition.

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.