Abstract:Coprolites are important vestigial fossils, which can provide information on dietary structure and population diversity of organisms, as well as reconstruct nutrient structure and energy flow models of ancient ecosystems. However, coprolites are often found in separate locations, and rarely regional continuous coprolites layer has been reported. This paper reports for the first time on the fossil horizons of coprolites, associated with leptodonts, phyllopods, alamites and reptiles found in the Dongyuemiao Member of the Ziliujing Formation in Yubei, Beibei, Wanzhou of Chongqing and Linshui of Sichuan in the early Jurassic, and samples the coprolites in the fossil beds. According to the morphological observation and thin section characteristics of coprolites, it is concluded that: (1) the collected coprolites are divided into four types, and their animal sources are mainly reptiles, bony fishes and cartilaginous fishes with different feeding habits. (2) during the Dongyuemiao period, the ancient Bashu Lake formed a complex ecosystem composed of lush plants as producers, bivalves and ostracoda as primary consumers, and fish and reptiles as medium-high consumers. (3) a small anoxic event occurred in the ancient Bashu Lake during the Dongyuemiao period, which led to the death of a large number of fishes in a cluster, and reptiles may were spared the trouble because they could breathe out of the lake. This anoxic event may be the prelude to the oceanic anoxic event of the Toar Period.