Monolophosaurus jiangi

A medium-sized theropod known from the Bajocian Epoch of the Middle Jurassic.  It is known from a mostly complete specimen that was about 5 meters (16.5) feet in length.  It's exact phylogenetic position in the theropod family tree is hard to place, with some considering it a basal Megalosaur, and others considering it to lie outside Megalosauroidea as a basal tetanuran.  It is known for a singular crest that runs along the length of it's skull.  It has been compared to the Proceratosaurid Guanlong in this similarity, and has even been suggested to be the adult form of the animal in the past, though it has generally been accepted that the two are distinct.  This crest may have been used as a display structure when it was alive.