The Giganotosaurus was one of the largest carnivorous dinosaurs. During the late Cretaceous period, around 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, although even the Giganotosaurus is among the carnivorous dinosaurs that were discovered only recently.