You can find these in the radiation zone of aberation red . Just saying watch out for theses guys when exploring or getting first rock Drake egg because if you on your high level ravager and your getting chased by reaper queen then one of theses pops out and dismounts you and Stuns your pet. All I can say is your doomed.
One day, I was in the redwoods with my assault rifle killing terror birds, and then out of nowhere, this boy jumps out and scares the flip out of me. So I run back to Pterry Cruise, (my pteranodon) and fly as fast away as I could. I circled back and filled him with holes.