Dinosaurs of the Lai family Dinosaurs of the Late Cretaceous period in the Heilongjiang Basin were reassessed

On July 11, the Journal of Vertebrate Paleontology (JVP), an international professional journal of paleontology, published an academic paper online entitled “Orthopaedic and Taxonomic Assessment of the Orunchun Heilongjiang Dragon (Dinosaur Duckbillosaurus) in the Upper Cretaceous Fishing Liangzi Group in Northeast China”. The research was done by a paleontological innovation team led by Zhang Yuguang, a researcher at the Beijing Museum of Natural History, and researchers from the Heilongjiang Geological Museum and the Jiayin Dinosaur Museum.

In this paper, researchers conducted a detailed orthopedic and taxonomic re-evaluation of the Orunchun Heilongjiang dragon (dinosaur-like Rydnosaurus subfamily) found in the upper Cretaceous (Middle Maastricht period) Yuliangzi formation found in the Wulaga site of the Heilongjiang River Basin in China.

Heilongjiang Long Pic .jpg

Ecological restoration of Amur dragon population in Ulaga region of northeast China Provided by Xinghai

Through a comprehensive comparison of the global platypus superfamily fossil materials, the authors gradually identified a series of dinosaur fossils of the subfamily Rydhaurus in the Ulaga region (previously mostly classified as Sahaliyania elunchunorum) and specimens from the contemporaneous Udur chukan formation in Blagoveshchensk, Russia. These shared orthopaedic features include a large lateral maxilla that is covered by the ventral end of the cheekbones junction, a narrow temporal area of the cheekbone (70% of the orbital width), an anterior third of the sagittal ridge of the parietal bone that descends along the dorsal abdomen, a wider maxillary tooth (1.2 teeth per centimeter) in a near-distant direction, a posterolasternal process slightly shorter than the anterior medial plate, and a slightly ventrally deflection of the intestinal tibabular anterior protrusion. In view of the contemporaneous sedimentation of the Yuliangzi Formation and the Udur Qiukan Formation in the Jieya-Breya Basin of the Heilongjiang River Basin and the above osteological similarities, the Orunchun Heilongjiang Dragon was identified as a secondary synonym of Amur Dragon of the Richteriform. Therefore, the abundance of duck-billed dragon species in the Late Cretaceous dinosaur biota in the Heilongjiang River Basin should be much lower than previously thought.

In the bone layer of the Ulaga site, about 70% of the complete Amurosaurus fibula is greater than 85 cm in length. These histological sections of the fibula all show moderate reconstruction of dense secondary bone units and weak vascularization of primary bone units of plasminous bone tissue outside the dense bone. This information confirms that most Ulaga fibula specimens should be in adulthood.


Skeletal reconstruction of Amur dragon (secondary synonym: Orenchun Heilongjiang dragon) Courtesy of Xing Hai

Based on the results of statistical analysis of bone histological observations and fibular bone measurement data, the researchers speculated that the Amurosaurus population in the Ulaga region was likely dominated by adult individuals. This situation differs significantly from the population structure of Amurosaurus at the Blagoveshchensk site in Russia, indirectly supporting the hypothesis that “large ornithischian dinosaur populations produced significant age segmentation between high and low latitudes”. Based on the largest minimalist phylogenetic analysis of the Lambeosaurinae subfamily, the researchers found a sister group relationship between Amurosaurus in the Heilongjiang River Basin and Rydonosaurus in western North America. The Lambeosaurini also obtained a high degree of resolution of branch relationships in this analysis.

The output of this research result benefits from the Strong Support and Funding of the National Natural Science Foundation of China, the Natural Science Foundation of Canada, the Beijing Municipal Natural Science Foundation, the Beijing New Century Million Talents Project, the Beijing Natural Museum New Museum Construction And Scientific Research Promotion Financial Project, the State Key Laboratory of the Ministry of Science and Technology and the special funds of the Department of Paleontology of the Canadian Museum of Natural History. (Source: China Science Daily Zhao Guangli)

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