"Microdontosaurus" (meaning "tiny-toothed lizard") is the name given to an as yet undescribed genus of sauropod dinosaur from China. It was named from fossils from the Middle Jurassic-age Dapuka Group of Xinjiang, and assigned to the Homalosaurpoidea, an outdated classification of diplodocids and titanosaurs. The intended type species is "M. dayensis." As with other informal names created by Zhao in 1985 or 1983, it has not been used since then, and may have been redescribed under another name.