Name: Omeisaurus ‭(‬Omei lizard‭ ‬-‭ ‬after Omeishan Mountain‭)‬.
Phonetic: O-may-sore-us.
Named By: C.‭ ‬C.‭ ‬Young‭ ‬-‭ ‬1939.
Classification: Chordata,‭ ‬Reptilia,‭ ‬Dinosauria,‭ ‬Saurischia,‭ ‬Sauropoda,‭ ‬Mamenchisauridae.
Species: O.‭ ‬junghsiensis‭ (‬type‭)‬,‭ ‬O.‭ ‬changshouensis,‭ ‬O.‭ ‬fuxiensis,‭ ‬O.‭ ‬jiaoi,‭ ‬O.‭ ‬luoquanensis,‭ ‬O.‭ ‬maoianus, O. puxiani,‭ ‬O.‭ ‬tianfuensis.
Diet: Herbivore.
Size: Around‭ ‬10‭ ‬to just over‭ ‬15‭ ‬meters long.‭ ‬Full size depends upon the species.
Known locations: China‭ ‬-‭ ‬Sichuan Province‭ ‬-‭ ‬Dashanpu/Lower Shaximiao Formation.‭ ‬Possibly also the Upper Shaximiao though these remains are widely regarded as being indeterminate.
Time period: Bathonian/Callovian of the Jurassic.
Fossil representation: Many individuals.

       With its incredibly long neck Omeisaurus is both a relative and possible comtempory to the more famous Mamenchisaurus.‭ ‬However previous Upper Shaximiao Formation fossils of Omeisaurus are now considered indeterminate.‭ ‬If Omeisaurus really‭ ‬does‭ ‬only exist in Lower Shaximiao deposits,‭ ‬then it may confirm that Mamenchisaurus replaced Omeisaurus since the former is only known from the later Upper Shaximiao.‭ ‬The large number of individual Omeisaurus recovered indicates that it was a successful design that was well suited to its environment.
       Other sauropod dinosaurs active at the same time and location as Omeisaurus include Abrosaurus,‭ ‬Dashanpusaurus and the clubbed tail Shunosaurus.‭ ‬Other herbivorous dinosaurs in the same time period and general area include the stegosaur Huayangosaurus and the small bipedal ornithischian Agilisaurus.‭ ‬Numerous predatory dinosaurs also roamed the landscapes and these include Chuandongocoelurus,‭ ‬Kaijiangosaurus,‭ ‬Gasosaurus,‭ ‬Leshansaurus,‭ ‬Xuanhanosaurus and Yangchuanosaurus.‭ ‬The last one in particular is important to Omeisaurus since it could attain sizes where it would have been a serious threat to smaller Omeisaurus,‭ ‬and still dangerous enough to worry larger individuals.

Further reading
- On a new Sauropoda, with notes on other fragmentary reptiles from Szechuan. - Bulletin of the Geological Society of China 19(3):279-315. - C.-C. Young - 1939.
- New sauropods from China. - Vertebrata PalAsiatica 2(1):1-28. - C.-C. Young - 1958.
- [Dinosaurs from the Jurassic of Sichuan]. Palaeontologica Sinica, New Series C, Whole Number 162(23):1-136. - Z. Dong, S. Zhou & H. Zhang - 1983.
- [Omeisaurus tianfuensis—a new species of Omeisaurus from Dashanpu, Zigong, Sichuan]. - Journal of Chengdu College of Geology 1984(suppl. 2):13-32. - X. He, K. Li, K. Cai & Y. Gao - 1984.
- Omeisaurus maoianus: a complete Sauropoda from Jingyan, Sichuan 1-128. - F. Tang, X.-S. Jin, X.-M. Kang & G.-J. Zhang - 2001.
- [A new species of Omeisaurus from the Middle Jurassic of Zigong, Sichuan]. - Vertebrata PalAsiatica 49(2):185-194. - S. Jiang, F. Li, G.-Z. Peng & Y. Ye - 2011.
- A new species of Omeisaurus (Dinosauria: Sauropoda) from the Middle Jurassic of Yunyang, Chongqing, China. - Historical Biology. - C. Tan, M. Xiao, H. Dai, X.-F. Hu, N. Li, Q.-Y. Ma, Z.-Y. Wei, H.-D. Yu, C. Xiong, G.-Z. Peng, S. Jiang, X.-X. Ren & H.-L. You - 2020.


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