Monolophosaurus (/ˌmɒnoʊˌlɒfoʊˈsɔːrəs/ MON-o-LOF-ə-SAWR-əs; meaning "single-crested lizard") is a genus of tetanuran theropod dinosaur from the Middle Jurassic Shishugou Formation in what is now Xinjiang, China. It was named for the single crest on top of its skull. Monolophosaurus was a mid sized carnosaurian carnivore at about 5 metres long.