First record of predatory fish Saurichthys from the late Early Triassic Nanzhang-Yuan’an fauna, South China

In the Early Triassic Nanzhang-Yuan’an fauna from South China, the occurrence of highly diverse marine reptiles suggests that by the late Spathian, the marine ecosystem already exhibited signs of recovery. However, there is currently no record of macrofossils other than marine reptiles found in this fauna. Here, we report the discovery of predatory fish Saurichthys from this fossil assemblage. The new Saurichthys materials are characterised by the derived saurichthyid character, i.e. highly reduced squamation of the trunk and large median scutes on the caudal peduncle. The adaptive features present in these new Saurichthys materials are crucial in generating thrust during rapid swimming or sudden acceleration, and therefore enhancing prey efficiency and evasion capacity, in consistence with the high predator pressure present in the Nanzhang-Yuan’an fauna. The discovery of Saurichthys in Nanzhang-Yuan’an fauna suggests that the trophic structure of Nanzhang-Yuan’an fauna is more complex than previously assumed.