 During this time , the area preserved in the Twin Mountains and Antlers formations was a large floodplain that drained into a shallow inland sea . A few million years later , this sea would expand to the north , becoming the Western Interior Seaway and dividing North America in two for nearly the entire Late Cretaceous . The Glen Rose Formation represents a coastal environment , with possible Acrocanthosaurus tracks preserved in mudflats along the ancient shoreline . As Acrocanthosaurus was a large predator , it is expected that it had an extensive home range and lived in many different environments in the area . Potential prey animals include sauropods like Astrodon or possibly even the enormous Sauroposeidon , as well as large ornithopods like Tenontosaurus . The smaller theropod Deinonychus also prowled the area but at 3 m ( 10 ft ) in length , most likely provided only minimal competition for Acrocanthosaurus . 
