Possible caudata tracks from the Middle Jurassic Yaopo formation in Beijing, China

Amphibian tracks are rare components of Mesozoic continental ichnoassemblages. Recently, the Middle Jurassic Yaopo Formation in Beijing, China, yielded a small isolated pes-manus set (imprints less than 2 cm in length and width) that can be attributed to an amphibian trackmaker. While the pes imprint is poorly preserved showing five indistinctly impressed short and broad digit traces and a broad palm impression posteriorly, the manus has a more clear morphology with four long and slender digit traces and a short, oval palm impression. In the pes digit IV seems to be longest and digit I shortest, in the manus digit III is longest, followed by II, IV and I which is shortest. Small acuminate claw traces are observed in the manus. Morphological similarities to other amphibian tracks from the global record are discussed, however, because of the isolated incomplete specimen lacking informations on a characteristic trackway pattern we avoid assignment to a distinct ichnotaxon. A detailed analysis and comparison of the Yaopo tracks with data from amphibian skeletal fossils and their autopodia suggest best match with Salamandroidea. Potential discoveries of further amphibian ichnofossils in the Yaopo Formation will enable a detailed environmental analysis including the present Middle Jurassic flora with ferns, gingkos, cycads, and conifers.