Datousaurus, meaning either "Chieftain lizard" or "Big-head Lizard" (from the Malay datou "chieftain" or Chinese da tou "Big Head" and Greek sauros/σαυρος "lizard") was a dinosaur from the Middle Jurassic. It was a sauropod collected from the Lower Shaximiao Formation in Dashanpu, Zigong Sichuan province, China. It shared the local Middle Jurassic landscape with other sauropods Shunosaurus, Omeisaurus and Protognathosaurus, the ornithopod Xiaosaurus and the early stegosaur Huayangosaurus as well as the carnivorous Gasosaurus.
Datousaurus was named by Dong Zhiming and Tang in 1984. To date, only two partial skeletons have been discovered. Neither had an articulated skull, although one skull has been discovered that has been attributed to the genus.
D. bashanensis is the only established species.
Datousaurus was about 15 metres long and herbivorous. It had a deep large skull for a sauropod. The rarity of its fossils suggest that it may not have been as social as other sauropods, which are often preserved in large numbers in a single deposit.
Datousaurus and Shunosaurus were both closely related animals with similar anatomies. However, Datousaurus's elongated vertabrae gave it a higher reach and its teeth were more spoon shaped. This may be a sign that these contemporaries fed on different plants and/or at different heights in the trees. This strategy may have reduced competition between the two genera. A similar pattern of height difference possibly associated with feeding behaviors is found in the diplodocids.