GEOGRAPHY

The Red River is the first fossil of the longest swollen ribosaur with a tail 200 million years ago


Long-tailed river dragon pattern specimen and sketch. (Courtesy of the research group)

Long-tailed red river dragon. (Courtesy of the research group)

Recently, a research team led by Xu Guanghui, a researcher at the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences, reported in the international academic journal Science Report that a new genus of marine reptiles, the long-tailed red river dragon, was about 244 million years ago. It is found in the early Triassic marine strata of Luxi County, Honghe Prefecture, Yunnan Province, China, with a total length of 47 cm, and its body shape resembles an aquatic lizard, and its extra-long tail is particularly special. Long-tailed red river dragon is the earliest definitive evidence of the family Plesiosaurus in China, representing the world’s longest tail (composed of 69 vertebrae) and the largest total number of vertebrae (121).

The research team has conducted more than ten years of continuous research on the Triassic marine strata in China’s Yunnan-Guizhou region, and Xu Guanghui, the first author and corresponding author of the paper, said, “When I first saw the red river dragon fossil, I asked the relevant experts for advice, but the defendant was that this was a Umong dragon fossil. I am skeptical of this, because Umenglong was found in the Panxian biota of Guizhou, which may have been slightly later than the Luoping biota, and the faces of the two biota are not the same. Considering the fossil’s potential biogeographic evolutionary significance, I decided to study it myself to solve the problem of its attribution.”

The study found that the red river dragon represented the transitional type between Umonglongosaurus and Qianlong, providing new fossil evidence for solving the phylogenetic relationships and biogeographic evolution within the Family Plesiosaurus. Judging from its long torso and slender front and hind limbs, the Red River Dragon mainly uses lateral fluctuations to advance in shallow sea environments, and its extra-long tail can further improve the efficiency of lateral fluctuations.

As early as 1854 , fossils of Ribosaurus were found in the Triassic marine strata of the European Alps. These European plesiosaurs are divided into five genera, all of which are classified into the family Plesiosaurus. The earliest named marine reptile in China was a species of swollen ribosaur called Hu Guizhou Dragon. It was discovered by Mr. Hu Chengzhi of the former Geological Museum of China in 1957 in Xingyi Dingxiao Luyin Village, Guizhou, and named by Academician Yang Zhongjian of the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences in 1958.

Zhao Lijun, a researcher at the Zhejiang Natural History Museum, a collaborator of the paper, said, “Hu’s Guizhou dragon was originally classified into the family Plesiosauridae, but later considering the differences with similar fossils in Europe, it was classified into the superfamily Plesiosaur family Guizhou Dragon family. The newly discovered Red River Dragon is 4 million years earlier than the Guizhou Dragon, closer to the European Leculosaurus, and represents the oldest fossil evidence of the Family Plesiosauridae in China. ”

After the extinction of organisms at the end of the Permian, the marine ecosystem underwent major changes in the Triassic, and reptiles radiated and evolved in the marine environment, forming marine reptile branches represented by ichthyosaurs, sea dragons and finnosaurs (including plesiosaurs, plesiosaurs, plesiosaurs and plesiosaurs). The Triassic marine strata in South China are widely distributed, and there are a large number of marine reptile fossils with rich phyla, which provides good conditions for studying the composition, food web and trophic level of marine ecosystems at that time. Liao Junling, a doctoral student at Guizhou University, a co-author of the paper, said, “The Red River Dragon is similar to the previously discovered Umong Dragon and Guixi Dragon, but its outer surface of teeth is relatively smooth, and the crown of the teeth is not significantly expanded, which is significantly different from the latter two, which may reflect the difference in eating habits between them.”

The research project has been funded by the Strategic Pilot Science and Technology Project of the Chinese Academy of Sciences and the National Natural Science Foundation of China. (Source: China Science Daily Cui Xueqin)

Related paper information:https://doi.org/10.1038/s41598-022-11309-2



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