| Named By: | J. Lu, L. Xu, H. Pu, X. Zhang, Y. Zhang, S. Jia, H. Chang, J. Zhang & X. Wei in 2013 |
| Time Period: | Early Cretaceous, 125-100.5 Ma |
| Location: | China, Henan Province - Haoling Formation |
| Size: | Uncertain |
| Diet: | Herbivore |
| Fossil(s): | Partial post cranial skeleton |
| Classification: | | Chordata | Reptilia | Dinosauria | Saurischia | Sauropodomorpha | Sauropoda | Somphospondyli | |
Yunmenglong is an extinct genus of somphospondylan sauropod known from the late Early Cretaceous of Henan Province, central China. Its remains were discovered in the Haoling Formation of the Ruyang Basin. The type species is Yunmenglong ruyangensis, described in 2013 by Junchang Lu et al. on the basis of an incomplete postcranial skeleton. Yunmenglong shares some characters with Euhelopus, Qiaowanlong and Erketu, and a phylogenetic analysis places it as a sister taxon of Qiaowanlong, both grouped with Erketu in a position more derived than Euhelopus but basal to Titanosauria. Yunmenglong represents the first long-necked sauropod dinosaur recorded from central China to date.