Characteristics and significance of Nanzhang/Yuanan Fauna, Hubei Province

Abstract: Nanzhang/Yuanan Fauna, which is yielded in the laminated limestone and micrite at the top of 3rd member of Jianglingjiang Formation, is characterized by marine reptiles, together with some Homoneneae and mollusk. The age of Nanzhang/Yuanan Fauna is late Olenekian Spathian of Early Triassic. The assemblage of marine reptiles in this fauna comprises Hupehsuchia, Ichthyosauria (Chaohusaurus), and Eosauropterygia (Hanosaurus, Keichousaurus, and Nothosauridae). Compared with other marine reptiles, Hupehsuchia has most abundance and diversity in this fauna. The high specialized skeleton of Hupehsuchia indicates that this animal should exist at the bottom of marine reptiles’ food chain. A lot of marine reptiles lived in Nanzhang/Yuanan Fauna, which indicates that marine ecosystem should begin recovery in late Spathian after late Permian mass extinction.