A palaeontologist has argued that T-rex could not have been a predator. He says this because few predators have small eyes needed to see prey, small arms needed to hold prey, and huge legs meaning slow speed, all of which are true of T-rex, and that there is no evidence for predation such as bones with T-rex teeth embedded in them. Instead, he argues it must have been a scavenger, as its skull shows it had a good sense of smell and its legs were suited for walking long distances. Other scientists disagree, pointing out that many predators do not use forelimbs in hunting and that the speed of any dinosaur is very hard to assess.