Acrocanthosaurus was the largest predator in all of Early Cretaceous North America. This giant was 36-40 feet long and weighed 3-5.5 tons. While a carcharodontosaur, Acrocanthosaurus had a sail like the spinosaur family, though it was more of a muscular ridge. The exact function of this ridge is unknown, though the extra muscle attachments likely made the animal more powerful. Acrocanthosaurus lived about 115 million years ago.