The giant predator Giganotosaurus attacks the sauropod Limaysaurus in South America 97 million years ago.. . Giganotosaurus is among the largest of all known land predators (43-46 feet long). It was longer than T-Rex, but not as heavy, but maybe quicker. Here it is attacking a sauropod of the time and region called Limaysaurus. Limaysaurus is actually related to Diplodocids rather than Titanosaurs. They are estimated at 50-60 feet long.