Acrocanthosaurus atokensis dinosaur, illustration. This species of dinosaur lived between 116-110 million years ago (Early Cretaceous) in what is now North America. Acrocanthosaurus was thought to be a very large bipedal predator. Its weight is estimated to have been up to 6.2 tonnes and it measured over 11 metres in length from head to tail. Fossils of Acrocanthosaurus show that it had a tall 'sail' made up of spines running along its vertebrae.