The Fossil Taphonomic Patterns and Age of the Newly Discovered Large Dinosaur Fossil Groups in the Yunyang Area, Northeast Sichuan Basin, China

In 2015, a large dinosaur fossil burial site was found in Pu’an Township, Yunyang, Chongqing, northeast of Sichuan Basin, which was another major discovery in the Sichuan after Dashanpu, Zigong. The fossils are enriched in the Middle Jurassic Xintiangou Formation and Shaximiao Formation. The main fossils of the Xintiangou Formation are dinosaurs, plesiosaurs, turtles, and fish. Their burial environment was on a lacustrine delta. The fauna living in the area were quickly buried by the sand carried by a river after death. At present, only dinosaur fossils have been found in the Shaximiao Formation, especially in the lower section, and a 150 m long fossil wall has been exposed. Its burial environment was a flood plain. The dinosaurs living in the area were quickly buried by a sand body spewed out by a mud volcano after their death.