New Discovery of Middle Jurassic Dinosaur Tracks in Chaya County, Eastern Tibet, China

The Changdu Basin in eastern Tibet was an important habitat for Jurassic dinosaur faunas, yet reports of dinosaur remains are scarce. Research on the composition of dinosaur assemblages, palaeoenvironments, and palaeobiogeography remains insufficient. This paper reports a dinosaur tracksite from the Middle Jurassic Dabuka Formation in Duolongwa Village, Chaya County, and discusses ichnomorphology, the trackmakers, their gait and speed, and sedimentary facies. Two tracklayers are observed. Theropod tracks from the DLW1 tracklayer are assigned to Eubrontidae ichnogen. et ichnosp. indet. (Morphotype-1). The trackmakers had hip heights of 0.98-1.77 m and body lengths of 2.56-4.67 m and primarily moved at a walking gait. Gasosaurus constructus is the most probable trackmaker. Sauropod tracks from the DLW2 tracklayer are assigned to Brontopodus isp. (Morphotype-2). The trackmakers had an estimated hip height of 2.96 m and a body length of 10.94 m. They were likely juveniles belonging to the Shunosaurus-Mamenchisaurus fauna. Sedimentological analyses indicate that the Duolongwa tracksite was a river point-bar-floodplain depositional system. The discovery of the Duolongwa tracksite demonstrates close links between the Middle Jurassic dinosaur fauna of eastern Tibet and cotemporaneous dinosaur faunas of the Sichuan-Yunnan areas, providing new evidence for faunal exchange among dinosaur assemblages across Southwest China.