spurs have always been the rule.although theres no real way. the spurs depend on the land. rocky soil country,a 3 yr. old may have worn off 1/2" to 3/4". where as a 2 yr. old in Fl. with sand may have 1 1/2" hooks. the beards wear off with dragging them and fires.
maybe a biologist may tell by the bones. can't say.