A basic, medium-sized Carnosaur that bears outward resemblence to Dilophosaurus, Monolophosaurus actually bears an interesting evolutionary convergence; A crest atop its head, like that of the crested Coelophysids. Monolophosaurus' crest, however, differed in that it was hollow, like the Lambeosaurine crests. The hollow canals in the crest led to the nasal passage, suggesting Monolophosaurus could sing through its crest, again just like the Lambeosaurines.

Monolophosaurus was discovered by paleontologists Currie & Zhao in 1994, the head & neck were found. There was also a discovery of pelvic fossils at a later date in Thailand. It is sometimes considered that Monolophosaurus was related to the Allosaurids, though there is little evidence to support any connection to any family, other than the obvious theropod ones. Monolophosaurus lived in China during the Jurassic, where the skull was found to have pre-mortem water indications. This is used as evidence to support the theory that Monolophosaurus was a partially aquatic dinosaur, using its crest like Parasaurolophus was thought to when first discovered.