As only the skull is known, it has proven difficult to provide a reliable size estimate of
Abelisaurus. It has transpired that abelisaurids have relatively short heads. In 2010,
Gregory S. Paul estimated its body length at , its weight at . In 2016, its length was estimated to be in a comprehensive analysis of abelisaur size. Others authors gave a similar size at 7.2 metres (23.6 feet) and 1.65 tonnes (1.82 short tons). Skull length was estimated at in 1985. The skull is relatively deep. Although there are no bony crests or horns, like those found in some other abelisaurids, such as
Carnotaurus, rough ridges on the snout and above the eyes might have supported some kind of crest made out of
keratin, which would not have become fossilized. The skull roof is thickened. There are also very large
fenestrae (window-like openings) in the skull, which are found in many dinosaurs and reduce skull weight. One of these is a large triangular
antorbital fenestra in the side of the snout. The eye socket behind it is rather high. It is constricted in the middle by bony projections of the
lacrimal bone in the front and the
postorbital bone at the rear. The eye was located above the constriction. Behind the eye socket a large triangular
infratemporal fenestra is present. Its form reflects a strong forward inclination of the back of the skull. The front snout bone, the
premaxilla, bore four relatively small teeth. The
maxilla behind it had at least seven, but perhaps as many as thirteen, larger teeth. ==Classification==