Hadrosaur fossils first discovered in southwest my country, was the Shu Road easy billions of years ago?

Author: Shi Xiangqi and Li Chuanfu

In the long history of life on Earth, dinosaurs are undoubtedly one of the most fascinating chapters. And in China, the discovery of dinosaur fossils always attracts widespread attention and research enthusiasm. On September 10, 2024, an exciting news came from Chongqing: Chinese scientists discovered the first duck-billed dinosaur, Qianjiangsaurus changshengi, in Qianjiang District, Chongqing. This discovery not only adds a strong stroke to the dinosaur fossil record in the southwest region, but also provides valuable evidence for studying the exchanges between dinosaur faunas in the Late Cretaceous of East Asia.

Excavation and restoration of Changsheng Qianjiangsaurus Source: Department of Earth Sciences

Hadrosauroids, also known as duck-billed dinosaurs, are a diverse and highly specialized group of ornithischian dinosaurs. They are known for their duck-billed skulls and complex tooth patterns. This group evolved from the iguanodonts and lived from the late Early Cretaceous to the end of the Late Cretaceous, on almost all continents around the world. The hadrosauroids have a unique head structure and chewing method, which makes them unique in the world of dinosaurs.

The lower jaw fossil of Changsheng Qianjiangsaurus Source: Department of Earth Sciences

The discovery of Changsheng Qianjiangsaurus is not only the first ornithopod dinosaur officially named in Chongqing, but also the first duck-billed dinosaur discovered in southwest China. The naming of this new genus and species not only reflects the regional characteristics of the fossil specimen production area, but also pays tribute to Mr. Wang Changsheng, the paleontologist who first reported the Qianjiang Cretaceous dinosaur fossils.

Restoration of Changsheng Qianjiang Dragon Source: Department of Earth Sciences

Changsheng Qianjiangsaurus exhibits a series of typical features of non-hadrosaurid hadrosauroids, such as a laterally wide U-shaped predentary and an almost vertical coronoid process of the dentary. At the same time, it also retains some "progressive" features commonly seen in hadrosaurids, such as the predentary marginal denticles being nearly trapezoidal, and each tooth socket accommodating at least 5 teeth. The combination of these features indicates that Changsheng Qianjiangsaurus is a late-branching non-hadrosaurid hadrosauroid dinosaur.

The discovery of Changsheng Qianjiangsaurus is not only of great significance in paleontology, but also provides biogeographical evidence of the exchange of dinosaur faunas in East Asia during the Late Cretaceous. By comparing it with the dinosaur faunas in southern Mongolia, the researchers found a close ecological correlation between the two in terms of dinosaur assemblage features, indicating biogeographical connections and dinosaur fauna exchanges between southern China and southern Mongolia during the late Late Cretaceous.

The discovery of Changsheng Qianjiangsaurus is an important contribution to the study of paleobiodiversity in China and even the world. It not only enriches our understanding of hadrosauroid dinosaurs, but also provides new clues for studying the evolution, distribution and paleoecology of dinosaurs in the Late Cretaceous. With the discovery and study of more fossils, I believe we will be able to uncover more mysteries about these prehistoric giants in the future.