South China Sea Culture Museum, Hainan Tropical Ocean University, Sanya 572022, Hainan, China

Total 960 tetrapod specimens from the Lujiatun bed, Lower Cretaceous Yixian Formation have been identified by the Paleontological Experts Committee of Liaoning Province since 2001. The relative abundance of 1 522 different tetrapod individuals is calculated, this fauna and its geological age is analyzed based on fossil and chronostratigraphic data. The Lujiatun bed is rich in volcanic debris, representing the abrupt volcanic mud flow at the margin of sedimentary basin. The geological age of the bed is roughly Valanginian to Hauterivian, Early Cretaceous. The tetrapods are autochthonous and dominated by terrestrial dinosaurs. Among them, Psittacosaurus is the dominant genus with relative abundance about 90%. Troodontids and Repenomamus is rich in the small theropod dinosaurs and mammals, respectively. Owing to the existence of several specimen which Repenomamus and Psittacosaurus were preserved together,they are considered predator and prey.This fossil community can be named as Psittacosaurus-Repenomamus Fauna.