It's called the chicken from hell: a birdlike dinosaur some 7 feet tall that weighed around 500 pounds when it roamed western North America on its long, slender hind legs. It had a toothless beak and a crest on its skull like a rooster's comb, combined with long arms and sharp claws up to about 4 inches long. It apparently also had feathers over much of its body. The dinosaur lived some 66 million to 68 million years ago in a hot and humid landscape, rather like the Louisiana bayou. It ate plants and maybe small animals when it wasn't fleeing from a hungry and much bigger T. Rex.. The reason it is called chicken from Hell? It was found in the Hell Valley area of North and South Dakota.