Giganotosaurus was one of the largest carnivores that ever lived in the Southern Hemisphere. It was up to 40-43 feet long and 6-8 tons in weight. Unlike T.rex, Giganotosaurus was a more lightly built carnivore, built for speed and agility over power. This carnivore had teeth that were designed like steak knives. At 6 inches long, they were perfect for tearing flesh. Giganotosaurus may have hunted in packs to bring down giant prey. They lived in South America 90 million years ago.