That is a great point about the bones, but hear me out on this theory. If they are a higher primate and they travel in small bands then it would seem that they take care of their deceased. Relative to the size of the wilderness and the limited exploration of it by humans, juxtaposed with the relativelty few numbers of said primates, i am not lost on the idea completely that we haven't found any bones. Just a thought.
Anything's possible, but it seems mighty unlikely.