Allosaurus

Allosaurus is a genus of predatory theropod dinosaur that lived in Europe and North America during the Jurassic Period between 155 and 150 million years ago. It is known in the "new world" to be a fearsome predator that mainly hunts in packs, feasting upon medium to large prey such as Stegosaurus. The species was discovered by Othniel Charles Marsh in 1877.