Reference collections of modern animal bone are an invaluable tool for identifying archaeological animal remains. Comparing the bones of known animal species to unidentified bones helps in determining class, family, species, and element. Identification of specific elements also aids in figuring how many animals are represented. For example, if the white-tailed deer bones from a site include two distal ends of right femurs, that means at least two animals are represented. Pictured is an underside view (ventral) of a bison skull that died of natural causes.