Omeisaurus (meaning "Omei lizard") is a genus of sauropod dinosaur from the Middle Jurassic Period (Bathonian-Callovian stage) of what is now China. Its name comes from Mount Emei, where it was discovered in the lower Shaximiao Formation of Sichuan Province. Like most sauropods, Omeisaurus was herbivorous and large. The largest species, O. tianfuensis, measured long, and weighed . Other species were much smaller, as the type species O. junghsiensis reached a size of in length and in body mass, and O. maoianus reached a size of and . Discovery and species Initial discovery and O. changshouensis The initial discovery of Omeisaurus was in 1936 when Charles Lewis Camp and Yang Zhongjian collected a partial skeleton from strata of the Shaximiao Formation in Sichuan, China. The material was taken to and prepared in what is now the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing. The skeleton was named Omeisaurus junghsiensis in 1939 by Yang Zhongjian, the skeleton consisting of a partial postcranial skeleton that included four cervical (neck) vertebrae. It was named after the sacred mountain Omeishan, which is near where O. junghsiensis was found, and the species name after the locality. The skeleton of O. junghsiensis was lost during WWII. In 1955, Xuanmin Li and colleagues collected several Sauropod remains from the same strata as O. junghsiensis in Changshou during construction of a reservoir. The IVPP sent Youling Su to conduct the excavation in Changshou, the crew finding eleven vertebrae and several appendicular elements (IVPP V930). The specimen was described later in 1958, also by Yang Zhongjian, as a new species, O. changshouensis. Discoveries at Wujiaba During the construction of the Wujiaba Dam in Zigong during the mid-to-late 1970s, crews discovered many large Sauropod remains from strata of the Upper Shaximiao Formation. The amount of material was vast and was collected by the Chongqing Museum of Natural History over five years, and was prepped and briefly described. The material consisted of many partial skulls and skeletons, consisting of between thirteen and sixteen individuals and 2 composite skeletons were later mounted in Chongqing and Zigong. Wujiaba also saw the collection of a fragmentary partial skull of an additional species of Omeisaurus, Omeisaurus fuxiensis, that was described by Zhiming Dong and colleagues in 1983. Dashanpu Quarry finds The next and most bountiful Omeisaurus discovery came in the 1980s when many dinosaur remains were found at Dashanpu in Zigong, these remains including