Known from a 85 cm long incomplete skull (about two-thirds of the MC 11098 holotype is known), lacking tip of snout, much of jaws, & parts of roof Abelisaurus was named in honor of Robert Abel (director of the Museo de Cipolletti, Cipolletti, Argentina, who found the specimen).

Abelisaurus ("Abel's lizard") was a primitive theropod that was roughly 21 to 25 feet (6.5 to 8 m) long, weighing roughly 1500 kg. Details of Abelisaurus bones prove it was related to Carnotaurus, although Abelisaurus had no horns, a longer head, and a hooked nose.

The antorbital and infratemporal fenestrae are exceptionalle large, diagnostic tyrannosaurid features are absent. Rather than projecting rostrally into the infratemporal fenestra, the slender descending process of the squamosal lies adjacent and parallel to the tall quadrate. The supratemporal recesses are not confluent but separated by a sagittel crest that is broad rostrally. The skull roof elements are thoroughly fused.