 Most accipitrids will supplement their diet with non-putrid carrion but, of course, none specialized with this as well as the 14-16 species of vultures, which have evolved very large bodies (which leave them equipped to fill their crop with carrion), weaker, less specialized feet relative to other accipitrids, large wingspans to spend extensively periods of time in flight over openings scanning for carcasses and complex social behavior in order to establish a mixed species hierarchy at carrion.The New World vultures have attained several similar characteristics, but only through convergent evolution and are seemingly not directly related to Old World vultures and other accipitrids.The lammergeier ("Gypaetus barbatus") is an aberrant cousin of the Old World vultures that has maintained strong feet in order to carry and drop large bones in order to crack them open to feed on bone marrow, their primary food, a technique they also sometimes use for live prey items, like tortoises.