You have to hit the body. We hit the head the first time and it did that was a 145. We Found a 130 and shot the body and it ko. Use catapults with boulders. Cannon also works but it needs to be a high level (125+) it it will be a one shot kill. If using a cannon then aim for the head. Should knock out with first cannon shot. If not the second will ko it.
Tranq Arrows/Darts DO NOT WORK!!! To knock this out you need to use a catapult and shoot in only on it's back. If you shoot it on it's legs it will kill it. UP-VOTE SO EVERYONE KNOWS & TO GET DODODEX TO ADD THIS!!!