Aucasaurus was a mid-sized abelisaur. This predator was roughly 16-20 feet long and weighed about 1 ton. Aucasaurus is the best understood abelisaur yet. This is because of the extremely complete skeleton that has been found. The skull however was damaged, leading some scientists to believe this individual was involved in a fight before it's death. Aucasaurus lived in South America about 80 million years ago.