This study introduces new discoveries of fossil footprints from the Middle Jurassic
Yaopo Formation in Beijing, China, marking the first reptile fossils that have been
discovered in this formation. The two small footprints with parallel digits and drag
marks suggest they were made by tetrapods moving through water. While there are similarities
to crocodylian and pterosaur tracks, the evaluation suggests that turtles are the
most likely trace-makers. If correct, the Yaopo Formation footprints are likely made
by xinjiangchelyids, given their dominance in Asian freshwater ecosystems during the
Late Jurassic and their widespread distribution in Late Jurassic China. Sichuanchelyids,
Bashuchelyidae, and Hongkongochelys are less likely candidates due to their limited
temporal and geographical distribution. This finding adds to the growing body of evidence
on the evolution and ecology of turtles in Asia during the Late Jurassic period. These
new findings offer important insights into the behaviour and spatiotemporal occurrence
of these ancient reptiles and expand our understanding of their role in prehistoric
aquatic ecosystems.
