Metriacanthosauridae is an extinct family of carnivorous allosauroid theropod dinosaurs. They tended to be large predators, some growing to sizes of 10 metres (33 ft). Metriacanthosaurids are carnosaurs, and many were initially classified within Megalosauridae or Allosauridae. A gigantic tooth belonging to what most likely is a giant sinraptorid has been described by Xu and Clarke in 2008.