Herrerasaurus was one of the first dinosaurs that ever lived. It was also quite large for it's time. It measured at least 10 feet long and weighed about 350 pounds, though some evidence suggests it was able to reach 15 feet in length and weigh over 1,000 pounds. Though there were other large carnivores that lived alongside Herrerasaurus, it was easily the biggest carnivorous dinosaur, some 2-3 times bigger than it's counterpart Eoraptor. Herrerasaurus lived in South America roughly 230 million years ago.