It is 66 million years ago in the warm and humid forests of Late Cretaceous South America, and the megaraptorid dinosaur Joaquinraptor casali is on the hunt. Growing at least 23 feet in length, this relatively slender creature would have probably been the apex predator of its region around the same time that T. rex stalked North America. Its most prominent weapons would have been the enlarged talons on its forelimbs.