BEIJING -- A China-led study has reported the discovery of amphibian track fossils in Middle Jurassic strata in Beijing, the first such record in Asia. The research has been published online in the journal Ichnos.

According to experts, the find not only fills a gap in the study of Jurassic amphibian trace fossils across Asia, but also provides key evidence for understanding the paleogeography, paleoecology, and biodiversity of northern China about 160 million years ago.

The fossils consist of two footprints preserved on a single slab. They were found on a roadside slope in Longquan town, Mentougou district in Beijing, forming a linked fore- and hind-foot pair, said Xing Lida, a dinosaur specialist and associate professor at the School of Earth Sciences and Resources, China University of Geosciences (Beijing).

Based on the relative size, spacing, and roughly aligned orientation of the two impressions, researchers determined that they were likely made by the same animal in the course of continuous movement.

One of the impressions, well-preserved, was identified as the left front footprint of a small animal, displaying a clear, fan-shaped morphology with four slender, pointed toes. The entire palm print measures only 1.5 cm in length and 1.3 cm in width.

To extract the maximum amount of information from these tiny impressions, the researchers employed modern digital techniques. They used photogrammetric 3D modeling to generate a high-precision 3D digital model, visually revealing the subtlest surface features of the impressions and providing a solid data foundation for morphological analysis.

Through detailed morphological comparisons and quantitative skeletal-track correlation analysis, the researchers concluded that the trackmaker most likely belonged to the salamander suborder.

"This is the first time that amphibian track fossils have been discovered and scientifically described in Jurassic strata in China and across Asia," Xing said. Previously, records of Jurassic vertebrate tracks in the Beijing area were dominated by dinosaurs and turtles, with no amphibian tracks reported.

This discovery indicates that during the deposition of the Middle Jurassic Yaopo Formation, small-sized, land-adapted amphibian groups existed in the lake-swamp environments of the Beijing area. They coexisted with abundant ferns, ginkgos, and cycads, forming a complex ecosystem.

It is worth noting that this important fossil was first discovered by Ni Jingchen, a Beijing elementary school student and fossil enthusiast, who came across it on a rocky slope in Mentougou while exploring in early 2025.

"This is a vivid example of public participation in paleontological discovery. It reminds us that the profound chapters of Earth's history are sometimes preserved in the subtlest traces of the surrounding rocks, waiting to be discovered and interpreted by those with a keen eye," Xing said.