Pterosaur tracks from the Lower Cantwell Formation (Campanian–Maastrichtian) of Denali National Park, Alaska, USA, with comments about landscape heterogeneity and habit preferences

Abstract

We report on new records of pterosaur tracks from Alaska. Recent palaeontological investigations in the Lower Cantwell Formation of Denali National Park, central Alaska Range, Alaska, had resulted previously in the discovery of a single pterosaur manus track. Subsequent and ongoing investigation has shown that the track record for pterosaurs in this region is more robust. These new pterosaur records comprise large and small traces. The larger tracks are up to approximately 18 cm long and 6 cm wide. The smaller tracks are approximately 6 cm long and 4 cm wide. The assemblage of pterosaur traces from Denali National Park consists of manus impressions. The morphology of the pterosaur traces found in the Lower Cantwell Formation compares favourably with the morphology of the ichnogenus Pteraichnus. The presence of two very different body sizes of pterosaurs, along with the abundant record of fossil bird tracks, indicates the presence of ecological complexity among aerial vertebrates during the time that the sediments of the Lower Cantwell Formation were deposited. Sedimentological and palaeobotanical data, combined with the vertebrate ichnology record, offer details into how these aerial vertebrates were separated within this heterogenetic ecosystem.