Acrocanthosaurus

Acrocanthosaurus ( ; ) is a genus of carcharodontosaurid dinosaurs that existed in what is now North America during the Barremian and early Cenomanian stages of the Early Cretaceous and Late Cretaceous, from 125 to 99.6 million years ago. Like most dinosaur genera, Acrocanthosaurus contains only a single species, A. atokensis. It had a continent-wide range, with fossil remains known from the U.S. states of Oklahoma, Texas, and Wyoming in the west and Maryland in the east. However, most of these remains are assigned to the species based on the assumption that Acrocanthosaurus is the only large carcharodontosaurid from North America during this time, and the possibility exists that some referred specimens could represent distinct taxa.

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 in length and in hip height and weighing about 7.5 metric tonnes (8.3 US tons) using a sail-backed model and 8.4 metric tonnes (9.3 US tons) using a hump-backed model. Large theropod footprints discovered in Texas may have been made by Acrocanthosaurus, although no direct association with skeletal remains has been found. Recent discoveries have elucidated many details of its anatomy, allowing for specialized studies focusing on its brain structure and forelimb function. Acrocanthosaurus was the largest theropod in its ecosystem and likely an apex predator that preyed on sauropods, ornithopods, and ankylosaurs.