The Giganotosaurus was one of the largest carnivorous dinosaurs. In the Late Cretaceous, about 99.6 to 97 million years ago, it roamed what is now Argentina. For a long time, the T. rex was considered the largest carnivorous dinosaur. Today, it is believed that the Giganotosaurus was slightly larger than a T. rex, even though the Giganotosaurus itself is one of the more recently discovered carnivorous dinosaurs.