Omeisaurus
A large herbivorous sauropod from Jurassic China.
Omeisaurus is a genus of sauropod dinosaur from the Middle to Late Jurassic Period of what is now China. Its name, meaning "Omei lizard," derives from Mount Emei, where it was discovered in the lower Shaximiao Formation of Sichuan Province. Like most sauropods, Omeisaurus was herbivorous and large, with the largest species reaching up to 20.2 meters in length.
Quick Facts
- Type species
- Omeisaurus junghsiensis
Facts from the source article.
Discovery and species
The initial discovery of Omeisaurus occurred in 1936 when Charles Lewis Camp and Yang Zhongjian collected a partial skeleton from the Shaximiao Formation in Sichuan. The material was prepared at what is now the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing. Yang Zhongjian named the skeleton Omeisaurus junghsiensis in 1939, based on a partial postcranial skeleton including four cervical vertebrae; the species name referenced the locality, and the genus name the sacred mountain Omeishan. In 1955, Xuanmin Li and colleagues collected sauropod remains from the same strata in Changshou during reservoir construction. Youling Su led the excavation, finding eleven vertebrae and several appendicular elements (IVPP V930). Yang Zhongjian described this specimen in 1958 as a new species, O. changshouensis. During construction of the Wujiaba Dam in Zigong in the mid-to-late 1970s, crews discovered many sauropod remains from the Upper Shaximiao Formation. The Chongqing Museum of Natural History collected the material over five years, which included many partial skulls and skeletons from thirteen to sixteen individuals; two composite skeletons were later mounted. A fragmentary partial skull of another species, Omeisaurus fuxiensis, was described by Zhiming Dong and colleagues in 1983.
Classification
Omeisaurus was once classified within Cetiosauridae, a wastebasket taxon. The species O. fuxiensis is sometimes confused with Zigongosaurus, though they are based on different material despite sharing the same species name. In 2021, John D'Angelo determined that all Omeisaurus species except O. maoianus were valid and likely belonged to the same genus, with O. junghsiensis as the most basal species.
Paleoecology
Omeisaurus lived in dense forests. Different species sometimes shared habitats, such as O. junghsiensis and O. tianfuensis. In the Xiashaximiao Formation, Shunosaurus and Datousaurus are also known, while Mamenchisaurus is present in the Shangshaximiao Formation. The large theropod Yangchuanosaurus from the Shangshaximiao probably preyed on sauropods, and the smaller Xuanhanosaurus was also present. In the Xiashaximiao, the theropod Gasosaurus and the herbivorous stegosaur Huayangosaurus were present; the latter likely did not compete with sauropods for food.
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