Appalachiosaurus is a genus of tyrannosauroid theropod dinosaur from the Late Cretaceous period of what is now eastern North America. It was a basal member of the clade Eutyrannosauria, meaning it was rather close in relation to the true tyrannosaurids such as Tyrannosaurus. Like most theropods, it was a bipedal predator. Only a juvenile skeleton has been found, representing an animal approximately 6.5 metres (21 ft) long and weighing 623 kilograms (1,373 lb), which indicates an adult would have been significantly larger.