Acrocanthosaurus ('high-spined lizard') is a genus of carcharodontosaurid dinosaurs that existed in what is now North America during the Aptian and early Albian stages of the Early Cretaceous, from 113 to 110 million years ago. Acrocanthosaurus was a bipedal predator. As the name suggests, it is best known for the high neural spines on many of its vertebrae, which most likely supported a ridge of muscle over the animal's neck, back, and hips. Acrocanthosaurus was one of the largest theropods, with the largest known specimen reaching 11–11.5 metres (36–38 ft) in length and weighing about 4.4–8.4 metric tons (4.9–9.3 short tons).