Abelisaurus comahuensis (Bonaparte and Novas 1985; Campanian, Late Cretaceous, 80mya) was a South American abelisaurid, the first ever described, known from a partial skull. Note the large postorbital intersecting the tall orbit. The mandible is restored.

Majungasaurus crenatissimus (Lavocat 1955, Krause et al. 2007; Late Cretaceous, 70mya; 6-7m in length) is an abelisaurid theropod dinosaur. In the large reptile tree it is related to Carnotaurus.

Carnotaurus sastrei (Bonaparte 1985; Bonaparte, Novas and Coria 1990; Late Cretaceous, 70 mya; 7.5m in length) is an abelisaurid theropod dinosaur related to Majungasaurus. Carnotaurus had a shorter, upturned snout, a shorter mandible, a deeper jugal, a narrower skull (below the horns) and a down-turned naris. Originally the horns were considered frontals, but here they are identified as lacrimals + prefrontals.

Bonaparte JF 1985. A horned Cretaceous carnosaur from Patagonia. National Geographic Research. 1 (1): 149–151.

Bonaparte J and Novas E E 1985. Abelisaurus comahuensis, ng, nsp, Carnosauria del Crétacico Tardio de Patagonia PDF [Abelisaurus comahuensis, ng., nsp, Carnosauria from the Late Cretaceous of Patagonia]. Ameghiniana 21: 259–265.

Bonaparte JF, Novas FE and Coria RA 1990. Carnotaurus sastrei Bonaparte, the horned, lightly built carnosaur from the Middle Cretaceous of Patagonia. Contributions in Science. 416: 1–41. PDF

Krause DW, Sampson SD, Carrano MT, O'Connor, PM 2007. Overview of the history of discovery, taxonomy, phylogeny, and biogeography of Majungasaurus crenatissimus (Theropoda: Abelisauridae) from the Late Cretaceous of Madagascar. In Sampson SD & Krause DW (eds.). Majungasaurus crenatissimus (Theropoda: Abelisauridae) from the Late Cretaceous of Madagascar. Society of Vertebrate Paleontology Memoir 8. pp. 1–20.

Other Majungasaurus papers are also found in this memoir devoted to this taxon.

wiki/Majungasaurus
wiki/Carnotaurus
wiki/Abelisaurus