Yesterday i tried killing one for xp and got killed 8 times. It also killed my argie. I got mad, threw a stone at him and flew away on my ptera. I was so disappointed and bored, so i spent rest of my day finding explorer notes. And guess what, i found two of these guys together near Central cave, then one on herbivore Island, and then one near whitesky peak. All these in just 1 day (real time).