A new specimen of Acrocanthosaurus atokensis (Theropoda, Dinosauria) from the Lower Cretaceous Antlers Formation (Lower Cretaceous, Aptian) of Oklahoma, USA

A new skeleton of Acrocanthosaurus atokensis is the most complete specimen collected and has the only known complete skull. Aspects of the new skeleton are described in detail, with special attention directed to the morphology of the skull and forelimb. Although unquestionably one of the largest theropods ever found, it is smaller than Carcharodontosaurus, Giganotosaurus and Tyrannosaurus. Comparison with other theropods suggests that Acrocanthosaurus bears a strong resemblance to these taxa because of characters that are size determinate, and the evidence suggests Acrocanthosaurus is more closely related to Allosauridae than to Carcharodontosauridae. Three families (Allosauridae, Carcharodontosauridae, Sinraptoridae) are recognized in the Allosauroidea.