Jiutaisaurus

Jiutaisaurus (meaning "Jiutai lizard") is a genus of sauropod dinosaur from the Quantou Formation of Jilin, China. Jiutaisaurus was a sauropod which lived during the Cretaceous. The type species, Jiutaisaurus xidiensis, was described by Wu et al. in 2006, and is based on eighteen vertebrae. It probably lived alongside Changchunsaurus and Helioceratops.

Discovery and naming
In September 2003, a team from Jilin University conducted a fossil excavation in Xidi Village, Jiutai, and recovered 18 caudal vertebrae from a sauropod, as well as some other fossils. In March 2006, Wu Wenhao, Dong Zhiming, Sun Yuewu, Li Chuntian, and Li Tao described the vertebrae as a new genus and species, Jiutaisaurus xidiensis, named for the discovery site.

Fossil record
Jiutaisaurus xidiensis is known only from the holotype specimen, CAD-02, which was recovered from the Cretaceous-aged Quantou Formation. The specimen consists of 18 articulated caudal vertebrae, hypothesized to represent the 11th to 28th vertebrae of the caudal series, and 13 haemal arches.

Classification
In their original description, Wu and colleagues tentatively classified Jiutaisaurus as a titanosaur, also noting similarities to Huabeisauridae and Brachiosauridae. Subsequent authors have considered it to be an indeterminate titanosauriform. Wilson and Upchurch, in 2009, considered it a nomen dubium.