Pu’an Township, Yunyang County, Chongqing City, where “the largest Jurassic original site in the world has been found as a single stone wall”, recently discovered a new large herbivorous dinosaur – Puxian Emei dragon. But new discoveries don’t stop here. A new “dinosaur mystery” has recently surfaced in Pu’an. In the process of conservation and excavation, researchers found that dinosaur fossils were also found in the strata older than the formation where the chemical stone wall is located. What’s more, the newly discovered dinosaur fossils may fill the gap of dinosaur evolution sequence from late Early Jurassic to Middle Jurassic.
The Puan dinosaur fossil group in Yunyang, Chongqing, includes the xintiangou formation and Shaximiao formation, which belong to the early early Early Jurassic to the late Middle Jurassic, and few dinosaur fossils of this period have been found in the world before. The Puxian Emei dinosaur found in Shaximiao Formation of Yunyang dinosaur fauna is a new species of dinosaur found in Yunyang after two new species of dinosaur, Modaoxi Sanxia dragon and Puan yunyanglong, were found in xintiangou formation of Puan dinosaur fossil group in Chongqing. The Puxian Emei dragon discovered in this study is an individual dinosaur with a preservation integrity of about 40%. Puxian is a species name and belongs to the genus Emei dragon. The fossil specimens found include vertebrae, forelimbs and hind limbs preserved in some joints, as well as clavicles and ribs preserved separately.
The researchers found that the unearthed fossils of Puxian Emei dragon are different from the known Emei dragon in characteristics. They have their own unique characteristics. For example, all the anterior vertebrae and posterior fovea, the middle cervical vertebrae have complex air cavity structure, the lateral fovea of the dorsal vertebrae is separated by secondary diaphragms, the anterior coccygeal vertebrae extend backward through the spine end, the deltoid crest of the humerus points to the posterolateral side, and the ratio of ulna to humerus is 0.69. After restoration and installation, Puxian Emei dragon is a large adult herbivorous dinosaur with a body length of about 16 meters and a height of more than 8 meters above the ground when standing.
TAN Chao, a researcher of Chongqing 208 Institute of geological heritage protection, said that Emei dragon is one of the main representative dinosaurs in the Middle Jurassic. The discovery of a new species of Emei dragon in Yunyang, Chongqing indicates the expansion of the distribution of Emei dragon and the enrichment of a group of Emei dragon, which is of great significance to the study of the individual evolution, development and migration of Emei dragon.
A group of dinosaur fossils from Pu’an, Yunyang, Chongqing, emerged from a bone like stone found by a young local farmer in Laojun village, Pu’an Township in January 2015. After identification and on-site investigation, the experts heard that there might be a large dinosaur fossil group in the Jurassic period. After two years of excavation and protection, the world’s rare 150 meter long single dinosaur fossil wall was detected in Pu’an township. The fossil wall includes 17 fossil enrichment areas, and there are a large number of dinosaur fossils buried more than 20 meters deep under the fossil wall. What’s more, the dinosaur fossil outcrops in Yunyang span four towns, with a distribution range of up to 15 kilometers along the stratum trend. After conservation excavation, the largest and most characteristic large-scale single fossil display wall of the original Jurassic site in the world formally appeared in front of the world in 2017, and the Puan dinosaur fossil group in Yunyang, Chongqing was also identified as a world-class dinosaur group by the national paleontological fossil Expert Committee in that year.
Chongqing area is one of the important dinosaur fossil burial sites in China, but before that, many dinosaur fossil excavation sites were single site, single skeleton or scattered fossils in a single era, and there were no groups and multiple types of dinosaur fossils buried in one site. At present, nearly 10000 fossils have been discovered in Pu’an dinosaur fossil group, Yunyang, Chongqing, including sauropods, sauropods, theropods, ornithopods, stegosaurs, as well as aquatic reptiles such as plesiosaurs and turtles and vertebrates without vertebrae, represented by bivalves.
Why are so many dinosaur fossils buried together? Xu Xing, a researcher of the Chinese Academy of Sciences, preliminarily analyzed that between 180 million and 160 million years ago, Yunyang area was the edge of ancient lake (Shuhu lake, Cuba). Groups of different kinds of dinosaurs living by the lake died in one or more emergencies. A large number of dinosaur skeletons drifting with the water precipitated and formed fossils when the velocity of the river into the lake delta slowed down. Therefore, Puan dinosaur fossil site in Yunyang, Chongqing belongs to “group burial in different places”. It is the body of many dinosaurs who died in different places and were “transported” to the same area by debris flow and flood. This can also explain why the arrangement of fossils in the fossil group is relatively disordered, and the age span is very large, and dinosaur fossils are distributed in many strata in the early, middle and late Middle Jurassic.
At present, research and excavation have shown that Chongqing Yunyang is another large dinosaur burial site in Southwest China after Zigong in Sichuan and Lufeng in Yunnan. Relevant departments have officially planned to build “ Jurassic Park” with Puan dinosaur fossil group in Yunyang, Chongqing as the core, so that more tourists can experience dinosaur theme Exploration Tour in dinosaur museum and dinosaur fossil Heritage Museum in the park.