Zigong dinosaur fossil group site was found in 1972. Many new dinosaur fossil genera and species have been found in this fossil group, including Mamenxilong, carnivorous dinosaur Yongchuan, short-bird-footed dinosaur and extremely precious primitive stegosaurus, which are really rare in Jurassic strata at home and abroad and have high scientific research value and sightseeing value, providing physical basis for studying the classification, ecology, physiology, evolution law, paleogeography and paleoclimate of dinosaurs and ancient reptiles. A total of about 130 dinosaur individuals were found in the excavation area of 2800 square meters, among which more than a dozen dinosaur bones were relatively complete. Therefore, this place is known as "the dinosaur cave, the wonder of the world" and "the national treasure of China" (Figure 2- 1).

Figure 2- 1 appearance of Zigong dinosaur museum (photography/Zhao Hongshan)

People can't help asking, why are there so many dinosaurs buried in Dashanpu, Zigong, Sichuan? In 1980s, Xia et al. (1988) thought that the dinosaurs in this area died suddenly due to arsenic poisoning, resulting in bone accumulation. Liang Bin and others (2009) think that Dashanpu in Zigong is a lake delta environment, where sandy shoals are developed, and dinosaur remains that died here and were transported from a distance by river water are buried by sand on the shoals. Body accumulation and sediment burial alternate. Later, after a long geological age, a sandstone layer containing fossils was finally formed (Figure 2-2).

Figure 2-2 Fossils Buried in Situ in Zigong Dinosaur Museum (Photo/Zhao Hongshan)