Tracks of a large archosaur from the Late Triassic Xujiahe Formation in Guangyuan, Sichuan, China

Late Triassic dinosaur skeletal records are missing in China, with only sparse dinosaur track occurrences documented in the southwestern and central regions. The Xujiahe Formation, situated along the northern margin of the Sichuan Basin, provides critical insights into the palaeoecosystems and sedimentary conditions of the region. A newly discovered Zilanba track site from the Fifth Member of the Xujiahe Formation near Guangyuan City, Sichuan Province, recorded ten tetrapod tracks. These small-sized tracks (majority of pes ranging 25–50 cm in length) comprise one trackway and four isolated tracks. Characterised by a medium gauge and possibly a low heteropody ratio (1: 2.3), although showing similarities with archosaurian tracks, they are tentatively attributed to basal sauropodomorphs. This site represents the ninth documented Triassic tetrapod track site in China and the third basal sauropodomorph track site of this period. This discovery enhances our understanding of the quantity and distribution of basal sauropodomorphs in Late Triassic of China. Furthermore, the Zilanba tracks provide new evidence supporting the previously proposed hypothesis of potential migration routes for basal sauropodomorphs from the western to the eastern Tethyan domain during this period.