The only discovered fossil of Abelisaurus is an incomplete skull. A large part of the right side of the skull is missing as well as most of the roof of the mouth. The skull itself is over 33 inches long, leading scientists to estimate that the Abelisaurus could reach lengths of up to 23 to 30 feet. Contrary to other Abelisaurs, there are no bony crests or horns on the skull, although there are rough ridges on the snout and above the eyes which may have supported a crest. The skull also has several large openings which are thought to have evolved in the skull of the Abelisaurus in order to lighten the weight of their massive skull.