The Giganotosaurus: Prehistoric Bolivia

The giganotosaurus (don't confuse giganotosaurus with gigantosaurus) lived in South America, specifically the very southern tip of the continent. Today that is Argentina. It was about 45 feet long and its name means "giant southern lizard". Its closest relatives were the Carcharodontosaurus and the Tyrannotitan. All of them were huge meat-eating dinosaurs that walked on their two back feet. The gigantosaurus was just as big, or even bigger, than the legendary Tyrannosaurus rex. It probably weighed more (about 8 tons) and was faster too; but the T-rex gets more attention because the first bones of the giganotosaurus weren't discovered until just recently in 1993.

No complete skeleton of a giganotosaurus has been found. It may have been big (the biggest carnivore in South America) but its brain was surprisingly small. It's main prey were sauropods (enormous long-necked herbivore dinosaurs). The giganotosaurus hunted in packs, and might have been the only predators the sauropods had to worry about. The giganotosaurus went extinct between 94 and 97 million years ago.