Mongolosaurus is a genus of titanosauriform sauropod dinosaur which lived during the Early Cretaceous of China.

[1] In 1928 a team from the American Museum of Natural History, headed by Roy Chapman Andrews, at On Gong Gol near Hukongwulong in Inner Mongolia, in Quarry 714 discovered a sauropod tooth.

Mongolosaurus was previously assigned to Diplodocidae, Titanosauridae and Euhelopodidae, though recent studies find it to be either a basal titanosaur or a non-titanosaurian somphospondylan.

They recovered Mongolosaurus as a derived member of the titanosaurian clade Lognkosauria, as the sister taxon to Jiangxititan.

The results of their phylogenetic analyses are shown in the cladogram below:[4] Diamantinasauria Xianshanosaurus Daxiatitan Australodocus Malawisaurus Aeolosaurus Rapetosaurus Isisaurus Saltasaurus Opisthocoelicaudia Alamosaurus Epachthosaurus Pitekunsaurus Tapuiasaurus Antarctosaurus Vahiny Jainosaurus Normanniasaurus Rinconsaurus Muyelensaurus Nemegtosaurus Mendozasaurus Argentinosaurus Futalognkosaurus Patagotitan Notocolossus Puertasaurus Jiangxititan Mongolosaurus