Acrocanthosaurus
Acrocanthosaurus' was a genus of theropod dinosaur that lived in North America during the Early Cretaceous period. Its classification is uncertain. It was originally classified as a spinosaurid, because the spines on its back resembled those of 'Spinosaurus'. However, 'Acrocanthosaurus' is now classified as a carnosaur. Most paleontologists believe that it was a carcharodontosaurid. Acrocanthosaurus' was 39 feet long, almost as large as 'Tyrannosaurus rex'. It was the largest theropod in North America before the evolution of the tyrannosaurids. There is a famous trackway in Paluxy, Texas that shows an 'Acrocanthosaurus' stalking its prey, a 'Paluxysaurus'.