An extremely recent find, Dreadnoughtus ranks among the largest land animals of all time. Adults measured in at some 80-85 feet in length and could weigh over 60-70 tons. It's skeleton is one of the most complete of the extremely large sauropods ever found. It was so huge, it would have had few, if any, predators. Dreadnoughtus lived in South America roughly 65-85 million years ago.