Identifying pterosaur trackmakers provides critical insights into mid-Mesozoic ground invasion

Fossilized tracks have provided unique insights into the distribution, behavior, and ecology of extinct taxa. Moreover, because they are abundant and often have distinct distributions in time and space compared with the body fossil record, they have considerable potential for testing and extending macroevolutionary hypotheses. The key to unlocking this vast potential lies in reliably linking tracks to their producers, but this remains a persistent challenge. This limitation is particularly evident among pterosaurs, the dominant flying vertebrates of the Mesozoic. Despite an extensive record of pterosaur tracks spanning more than 100 million years, the identities of trackmakers are unclear in most cases, limiting their use for addressing key questions about pterosaur ecology and evolution. In this study, we employ quantitative analyses and diagnostic features of pedal anatomy to directly link three distinct pterosaur track morphotypes to specific pterodactyloid clades: ctenochasmatoids, dsungaripterids, and neoazhdarchians. These results considerably extend the known biogeographic distribution of these clades, supporting macroevolutionary and ecological hypotheses derived from analyses of the body fossil record. The absence of pterosaur tracks prior to the Middle Jurassic supports evidence from hand and foot morphology indicating that early pterosaurs were arboreal or scansorial. Track evidence demonstrates a major radiation of derived pterodactyloid pterosaurs into terrestrial niches beginning in the Middle Jurassic. Successive clades maintained a strong presence across diverse terrestrial environments throughout the latter half of the Mesozoic, highlighting the evolutionary versatility and ecological significance of pterosaurs in terrestrial environments.