Abstract:

A large number of continental basins in northeastern and northwestern China contain abundant vertebrate fossils in lacustrine deposits. Among them, the Wuerho Pterosaur Fauna from the Junggar Basin on the north side of the Tian Shan Mountains, the Hami Pterosaur Fauna from the Turpan-Hami Basin on the south side of the Tian Shan Mountains, and the Jehol Biota of western Liaoning, all bear rich pterosaur fossils. The former two faunas of northwestern China shared similar prosperous time and were both discovered in the Lower Cretaceous Tugulu Group. Pterosaur diversity of these two faunas is low but the faunas included abundant individuals. Fossils of the Wuerho Pterosaur Fauna, preserved mostly in the fine-sandstones and siltstones of the semi-deep lacustrine deposits, were relatively complete and formed by normal death. The fossils of the Hami Pterosaur Fauna were largely preserved in the tempestites of the event deposits of a shore-shallow lake. The disarticulated bones were complete after the short-distance transport by storms and a fast burial. By contrast, the pterosaurs of the Jehol Biota of northeastern China have high diversity as well as an association with fishes, amphibians, dinosaurs and other reptiles, and birdsand mammals, They were mainly preserved in the semi-deep to deep lacustrine shales. The skeletons are relatively complete, as a volcanic eruption caused massive death and fast burial (by volcanic ashes) creating a very different outlook from that of the two northwestern faunas. Based on the preliminary comparison of the pterosaur faunas from the south and north sides of the Tian Shan Mountains, we inter that the dominant pterosaurs on the north side, dsungaripterids, are distributed in the Junggar Basin and neighboring western Mongolia, that they have a distant relationship with the only known taxon, Hamipterus, from the faunas from the south side. Hence, we have proposed that the Tian Shan Mountains rose to a relatively high level in the Mesozoic, blocking the migration of the faunas from both sides of the mountains. In western Liaoning and its neighboring regions, the destruction of the North China Craton caused abundant volcanic eruptions, which created a highly diversified ecological environment with rapid replacements of creatures thus resulting in unique biodiversity in the Jehol Biota. However, the continental basins in northwestern China, which experienced no volcanic eruption, have low diversity but high abundancy of pterosaurs. Therefore, we proposed that the frequent and intense volcanic eruptions caused by the destruction of the North China Craton played an essential role in the varying diversity between the pterosaur faunas of northeastern and northwestern China.

Key words: Wuerho Pterosaur Fauna, Hami Pterosaur Fauna, Jehol Biota, biodiversity, Early Cretaceous, China