Omeisaurus

*Omeisaurus junghsiensis*

***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. It was 49.2 feet (15 meters) and weighed 15-20 tonnes. It was a long-necked Sauropod, probably a close relative of Mamenchisaurus. The long neck would have been useful to reach high into trees or to cover a wide area on the ground. Omeisaurus is primarily only known for its medium size and incredible neck.

It was discovered in 1939 by paleontologist Yang Zhongjian. The length of its neck, however, wasn't revealed until the 1980s, when a more complete skeleton was uncovered, and revealed.

## Discovery

*Omeisaurus* was first described in 1939. It was named after the sacred mountain Omeishan, which is where the first fossil example of *Omeisaurus* was found. Most skeletons of *Omeisaurus* were found in the 1970s and 1980s, during the great “Chinese dinosaur rush”. There have been six species of *Omeisaurus* named so far: *O. junghsiensis*, *O. changshouensis*, *O. fuxiensis*, *O. tianfuensis*, *O. luoquanensis*, and *O. maoianus*. All of these but the last were named after the locations where they were found. *O. fuxiensis* was the smallest species, measuring around 35 feet (11 m) long. *O. tianfuensis* had the longest neck of the genus, around 30 feet (9.1 m) long. The only dinosaur with a longer neck was *Mamenchisaurus*. A club tail fossil discovered in the same bone bed as the *Omeisaurus* fossils was thought to belong to this genus, but is now believed to belong to a large specimen of *Shunosaurus*.

Mounted skeletons of *Omeisaurus* are on display at the Zigong Dinosaur Museum in Zigong, Sichuan Province and at Beipei Museum, near Chongqing, both in China.

## Classification

It was once classified as a member of the Cetiosauridae family, which had long been a wastebasket taxon. The species *O. fuxiensis* is sometimes confused with *Zigongosaurus*, but the two are based on different material despite having the same species name.

*Omeisaurus* is presently counted as a member of the Omeisauridae, Mamenchisauridae, or Euhelopodidae. The general linkage of the genus with *Mamenchisaurus* et al. is the basic theme of including it in the omeisaurid or mamenchisaurid families. However, *Omeisaurus* is similar to many non-mamenchisaurid Chinese eusauropods classified as euhelopodids.

The cladogram below shows a possible phylogenetic position:

## Paleoecology

The Omeisaurus lived during the Middle, and possibly Early Jurassic Period in China. It shared its grazing marshes with more primitive Sauropods, like the Shunosaurus, and was probably terrorized by Gasosaurus, a 4-meter carnivore that lived alongside it. Gasosaurus may have been small, but for its time and location, it was probably one of the top predators.

## JPInstitute.com Description

Omeisaurus was a long-necked dinosaur that lived in what is now China. It is a well-known dinosaur to many Chinese, but not very well known elsewhere. It had a neck that was very long compared to some other sauropods, but other than that, it was just like other members of its family in that it had a long tail, stout legs and was really big.

Some scientists believe that this dinosaur may belong in the same family as Mamenchisaurus because of its extremely long neck. However, it is currently classified in the same family as Shunosaurus, which had a club on its tail. A club tail was found associated with the remains of Omeisaurus in a bone bed, but it is now assumed that the tail belonged to a large Shunosaurus specimen.

Many people don't realize that China is one of the most prolific areas for the discovery of dinosaurs. The Sichuan Province is perhaps the best place in the world to find Jurassic dinosaurs

## Links

http://web.archive.org/web/20031221145455fw\_/http://www.jpinstitute.com/dinopedia/dinocards/dc\_omeis.html