Cretaceous pterosaur history, diversity and extinction

Abstract

Pterosaurs, the first vertebrates to evolve powered flight, dominated Mesozoic skies from the Late Triassic to the end Cretaceous, a span of around 154 million years (∼220 mya to 66 mya). They achieved their greatest diversity in the mid-Cretaceous and had become globally distributed, even occurring at high latitudes and in a wide range of habitats. The pterosaur record is dominated by occurrences in conservation Lagerstätten in just a handful of countries and a narrow range of temporal windows, most notably China, Germany and Brazil and the Middle-Upper Jurassic and mid-Cretaceous respectively. During the Cretaceous two major pterosaur clades evolved edentulism, such that by the end of the Cretaceous, no toothed pterosaurs survived, having become extinct by the mid-Cenomanian. A distinctive aspect of pterosaur evolution during the mid-Cretaceous was the achievement of gigantic wingspans, perhaps in excess of 10 metres, hyper-elongation of the neck vertebrae in Azhdarchidae, and the evolution of highly elaborate cranial crests. For many years, pterosaur diversity in the terminal stage of the Late Cretaceous was regarded as low, but discoveries in the last few decades have indicated pterosaur taxic diversity remained high until the end Maastrichtian, although morphological diversity may have been low. The demise of the Pterosauria at the K/Pg boundary was most likely due to the same causes as the coeval dinosaur extinction associated with the Chicxulub bolide impact and its environmental repercussions. Faunal replacement by avians is no longer considered a significant factor in pterosaur extinction.