Improvement for the reconstruction of paleoaltitude and paleoenvironment based on the Hipparion fossils in Mount Shisha Pangma region
In the first scientific expedition to the Tibetan Plateau,the discovery of the Hipparion fauna in the Late Miocene Woma Formation of the Gyirong Basin in the area of Mount Shisha Pangma became one of the most important pieces of evidence for the uplift process of the Tibetan Plateau.In the subsequent investigation,some new fossils of the Hipparion horse were discovered around Mount Shisha Pangma and other areas of the Tibetan Plateau,which still played a very important role in the study of the uplift process of the Tibetan Plateau.We studied the new Hipparion fossils collected from the Gyirong Basin in the area of Mount Shisha Pangma,that have the following morphological characters:the absence of longitudinal grooves on the labial side of the incisors and the hypocone contraction;the small protocone of the upper cheek teeth and the weak plications;the nearly rounded double knots of the lower cheek teeth with a shallow,wide and U-shaped linguaflexid;the shallow ectoflexid in the lower premolars.These characters are completely identical with the diagnosis of Hipparion forstenae,which was previously found in the Gyirong Basin.The diversity of the family Equidae has rapidly increased since 18Ma in the Miocene,as evidenced by the high adaptation of the forms with high-crowned teeth to radiation,and reached its peak with the spread of open grasslands.Since the migration of the Hipparion horses from North America to the Old World in the early Late Miocene,there has been a very prosperous distribution of the Hipparion fauna in many locations,among which the genus Hipparion usually had multiple species coexisting.Currently,there is only one species of Hipparion in the known Hipparion fauna from the hinterland of the Tibetan Plateau,which is a very rare phenomenon.In the modern Tibetan Plateau,the number of species vary with altitude,with the highest species richness in mid-altitude areas and a significant decrease in high altitude areas above 2500m.We compare the species diversity of Hipparion from the hinterland of the Tibetan Plateau with the northern and southern sides of the plateau as well as the eastern and western areas of the plateau in the Pan-Third Pole region.The results show that this phenomenon is due to the special terrain,climate and environment caused by the strong uplift of the Tibetan Plateau during the Neogene Period.
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万方数据
维普
