Manus and pes morphology maps the invasion of terrestrial environments by pterosaurs in the mid-Mesozoic

Pterosaurs, the first true flying vertebrates, played a crucial role in Mesozoic terrestrial ecosystems. However, our understanding of their non-aerial locomotion and palaeoecology remains limited. Here, we demonstrate an unexpectedly high degree of disparity in manual and pedal anatomy across Pterosauria comparable to that observed in extant birds and lepidosaurs. This suggests that pterosaurs occupied a remarkably broad range of locomotor ecologies. Non-pterodactyliform pterosaurs exhibit extreme modifications to their autopodial proportions representative of scansorial lifestyles. Conversely, pterodactyliforms typically exhibit autopodial morphologies consistent with more terrestrial locomotor ecologies. These changes in autopodial proportions, combined with modifications to other aspects of pterosaur anatomy, map a significant event in tetrapod evolution: a mid-Mesozoic colonisation of terrestrial environments by pterodactyliforms. This transition to predominantly terrestrial locomotor ecologies did not occur as a single event coinciding with the origin of Pterodactyliformes but evolved independently within each of the four principal pterodactyliform radiations: Euctenochasmatia, Onithocheiroidea, Dsungaripteroidea and Azhdarchoidea. Adaptation to terrestrial environments by pterosaurs facilitated the emergence of a wide range of novel feeding ecologies, while the freedom from limitations imposed by scansoriality permitted an increase in body size, ultimately enabling the evolution of gigantism in multiple lineages.