Abstract:
The main marine reptiles spread the eastern Paleotethys and western Panthalassa Ocean during the biotic recovery in the Early Triassic. The Nanzhang-Yuan'an fauna is one of the earliest marine reptiles in the Early Triassic. However, the specific survival time of this fauna and the fossil-bearing Jialingjiang Formation are still not well defined. Here, we conducted litho-stratigraphy and isotopic dating on the Nanzhang-Yuan’an fauna in the Nanzhang-Yuan’an area of Hubei Province. The fauna is documented in the laminated limestone of the upper Jialingjiang Formation, with a SHRIMP II U-Pb age of 247.8 ± 1.2 Ma. The stratigraphic framework for the upper part of the Jialingjiang Formation was established, proving that the Nanzhang-Yuan'an fauna lived in the late Spathian stage of the Early Triassic.