Acrocanthosaurus - Paleoecology

Paleoecology

Definite Acrocanthosaurus fossils have been found in the Twin Mountains Formation of northern Texas and the Antlers Formation of southern Oklahoma. These geological formations have not been dated radiometrically, but scientists have used biostratigraphy to estimate their age. Based on changes in ammonite taxa, the boundary between the Aptian and Albian stages of the Early Cretaceous has been located within the Glen Rose Formation of Texas, which may contain Acrocanthosaurus footprints and lies just above the Twin Mountains Formation. This indicates that the Twin Mountains Formation lies entirely within the Aptian stage, which lasted from 125 to 112 million years ago. The Antlers Formation contains fossils of Deinonychus and Tenontosaurus, two dinosaur genera also found in the Cloverly Formation of Montana, which has been radiometrically dated to the Aptian and Albian stages, suggesting a similar age for the Antlers. Therefore Acrocanthosaurus most likely existed between 125 and 100 million years ago.

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 Paluxysaurus or possibly even the enormous Sauroposeidon, as well as large ornithopods like Tenontosaurus. The smaller theropod Deinonychus also prowled the area but at 3 meters (10 ft) in length, most likely provided only minimal competition for Acrocanthosaurus.