Just before the end of the level, pass the big jump, then back up to the left 
end of the last platform to fall down. You will land in a hidden area. Note: You 
will crash if you do not land correctly. Stop very fast to avoid the large pile 
of bombs. This area has some primitive structures made from 2x4s of a deer and 
someone shooting at it with a bow and arrow. Get past the pile of bombs to find 
a wall drawing made from wood planks.