Giganotosaurus (meaning 'giant southern lizard', derived from the Ancient Greek gigas/γίγας meaning 'giant', notos/νότος meaning 'south wind' and -saurus/-σαύρος meaning 'lizard') is a genus of carcharodontosaurid dinosaur that lives in the Rainy Basin. It is one of the largest known terrestrial carnivores, slightly larger than Tyrannosaurus.


Giganotosaurus is slightly larger than T. rex, but has a brain only about half as big as those of tyrannosaurids. The teeth of Tyrannosaurus are longer and wider, but more variable in size. The teeth of Giganotosaurus are shorter, less variable and narrower than those of Tyrannosaurus, and are more adapted for slicing flesh. A well-developed olfactory region means that it has a good sense of smell. Its skull, although large, has a slender build.


Giganotosaurus, along with relatives like Acrocanthosaurus, are members of the carnosaur family Carcharodontosauridae.