Mapusaurus was a genus of large carnivorous dinosaurs. Like its cousins Giganotosaurus and Carcharodontosaurus, it was an allosaur in the family Carcharodontosauridae, and from South America in the Cretaceous Period. It was a contempory of Giganotosaurus and the two form the sub-family Giganotosaurinae within Carcharodontosauridae. The type and only species is Mapusaurus rosae.
The fossil remains of Mapusaurus were discovered in a bone bed containing at least seven individuals of various growth stages. Coria and Currie speculated that this may provide clues about theropod behavior. Other known theropod bone beds include the Allosaurus-dominated Cleveland Lloyd Dinosaur Quarry of Utah, an Albertosaurus bone bed from Alberta and a Daspletosaurus bone bed from Montana.
Mapusaurus was similar in most respects to Giganotosaurus, but there were a few differences. It was slightly longer but less heavy, with narrower jaws and a few other differences in the bone positioning and size. Like Giganotosaurus, Mapusaurus had widely splayed feet, wider than the feet of most theropods. This probably meant Mapusaurus made less noise when walking than most theropods, such as Tyrannosaurus Rex and Spinosaurus. The widely splayed feet may also have given Mapusaurus better balance and enabled it to walk on loose surfaces, such as sand.
Mapusaurus was likely a large Theropod, probably even longer than Giganotosaurus and Tyrannosaurus, but likely less sturdily built. But at 12.2-13.6m long and 5-8t in weight it was a big Theropod. Its skull measured around 1.8m long, the same length of the holotype Giganotosaurus skull.