I find bones all the time, and occasionally carcasses. In the winter, carcasses seem to last much longer. There are some exceedingly rare animals in North America, and people still seem to find evidence of them from time to time...yet never any proof of big foot.

Therefore I think there's a lot of validity to the argument that if there was an 8-ft beast running around in the woods, someone would have produced proof of it by now. They don't exist.