The biggest dino in Ark is the Giganotosaurus. It is a massive theropod dinosaur that lived during the late Cretaceous period. It was first discovered in South America in the early 20th century and was one of the largest land predators ever discovered. The Giganotosaurus was about 40 feet long and weighed around 8 tons. It had a large head with sharp teeth, and its arms were relatively small compared to its body size.