Turtle tracks from the middle Jurassic Yaopo formation in Beijing, China

ABSTRACT

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.

KEYWORDS:

• swim traces
• Yaopo formation
• turtle

Acknowledgments

The authors thank Li LI for his participation in early discussion. We also thank the Jens N. Lallensack and other anonymous reviewers for their comments on an earlier draft of the paper.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The National Natural Science Foundation of China (No. 41888101), the 111 project (B20011), the Fundamental Research Funds for Central Universities (265QZ201903)