Mei's rhinoceros jaw and lower buccal teeth (courtesy of Chen Shaokun)
Mei's rhinoceros cheek teeth (courtesy of Chen Shaokun)
It is mainly distributed in the Palearctic fauna, and is more common in Europe, Siberia and northern China, and is generally considered to be a representative species of the temperate environment in the north. Chen Shaokun and Huang Wanbo of the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences found fossils of Mei's rhinoceros or stephanorhinus kirchbergensis in a late Pleistocene paleoanthropology site in Labyrinth Cave, Wushan County, Chongqing, about 13,150 years ago, including skull fragments, jaws, teeth and several post-head bones. The study was published in the latest issue of the Journal of Anthropology (Vol. 31, No. 4). This finding is of great significance for the study of the paleoclimate environment of the late Pleistocene in the Three Gorges region.
Labyrinth Cave is located on the east bank of the Baolong River on the south bank of the Yangtze River, 12 kilometers away from the confluence of the Baolong River and the Yangtze River, and the administrative division belongs to Xinjian Village, Heliang Town, Wushan County, Chongqing City, with geographical coordinates of 30°32′n; 108°52′e, and the entrance to the first cave is 165 meters above sea level. From November to December 1999, Huang Wanbo and others conducted a test excavation at this site and found a large number of human and mammal fossils and Paleolithic tools. The rhinoceros fossils were identified as dicerorhinus sp., which were identified as two-horned rhinoceros due to their small number, but in fact, before the labyrinth hole was excavated, the workers who developed tourism in this cave had excavated a batch of fossils, and in 2008, because they learned of the importance of this batch of fossils, they were handed over to Professor Huang Wanbo and others who were investigating here. Based on these fossils, the rhinoceros material of the labyrinth hole was further identified as a Meseria rhinoceros.
According to Chen Shaokun, the first author of the article, the fossil rhinoceros of Chongqing's Wushan Labyrinth Cave was identified as a Mei's rhinoceros due to the loss of lower incisors, the sub-high crown of the buccal teeth, and the significant contraction of the original tip of the upper molar, which is the latest fossil record and the most southern distribution of this species found in the world. Mei's rhinoceros is an animal that prefers a warm and cool environment, and if it is normal to appear in the range of Shennongjia at an altitude of more than 2,000 meters, the appearance of Mei's rhinoceros in the labyrinth cave has a more important paleo-environmental significance, indicating that during the last glacial period, the climate in this area may be more similar to that of today's North China.
Based on labyrinth caves and other Mei's rhinos in the Yangtze River Basin, the researchers believed that there were more or less differences in the morphology of cheek teeth in the southern, northern and European Mei's rhinoceros in China, thus dividing this species into three types. The main differences are in size, primary tip contraction, degree of development of small spines, and morphology of the posterior valley of the lower anterior molars.
From the perspective of distribution range, the current southern type of Rhinoceros is only found in the Three Gorges and the Yangtze River Basin east of the Three Gorges. Based on the specimens that can be observed so far, the researchers believe that this type migrated from the north, but spread southward only to about 30° north latitude, and did not spread south. Based on this, the researchers speculate that the emergence of the ice age in the Pleistocene period forced the Mesquite rhinoceros, which adapted to the temperate climate, to move south, gradually adapt in the diverse woodland environment of the Yangtze River Basin, and evolve some unique morphological characteristics.
The research was funded by the National Key Basic Research and Development Program of China and the National Natural Science Foundation of China