Prehistoric sloths were much larger then modern day sloths and roamed the north american continent in the Pleistocene era (ice age). I have since looked up a pic of one and data and found that the foot had claws for stripping bark, etc., a food source. So don't know, but it still looks like sloth. Send your pic to the one of several good universities in because, Simon Fraser is one, anthropology dept., and see what they come up with.
Good lucky find !