 David K. Smith , examining Allosaurus fossils by quarry , found that the Cleveland Lloyd Dinosaur <unk> ( Utah ) specimens are generally smaller than those from <unk> Bluff ( Wyoming ) or <unk> Young University 's Dry Mesa <unk> ( Colorado ) , but the shapes of the bones themselves did not vary between the sites . A later study by Smith incorporating Garden Park ( Colorado ) and Dinosaur National Monument ( Utah ) specimens found no justification for multiple species based on skeletal variation ; skull variation was most common and was <unk> , suggesting individual variation was responsible . Further work on size @-@ related variation again found no consistent differences , although the Dry Mesa material tended to clump together on the basis of the <unk> , an ankle bone . Kenneth Carpenter , using skull elements from the Cleveland Lloyd site , found wide variation between individuals , calling into question previous species @-@ level distinctions based such features as the shape of the horns , and the proposed differentiation of " A. jimmadseni " based on the shape of the jugal . 
