Monolophosaurus, meaning “single-crested lizard”, is a genus of carnosaurian dinosaur from the Middle Jurassic Period (170 million years ago) that lived in what is now China. It was named for the single crest on top of its skull. The remains were dug up in 1984 and were described by Currie and Zhao and their colleagues. This dinosaur was first known as Jiangjunmiaosaurus, but was later renamed as the species M. jiangjunmiaoi.
It was about 17 feet long as an adult, and stood nearly 6 feet high. It weighed up to 1,500 pounds. Monolophosaurus was initially believed to be a Megalosaur and has often been misinterpreted as an allosaurid. Some primitive characteristics show that this animal may have been a primitive tetanuran dinosaur.