So I've been trying to tame one all morning, and I've come across this knowledge. Any type of armour is sufficient, I use chitin bc It's what I keep on me at all times. Use a Ptera, grab the Alpha, and fly it far from the pack. Set it down in an area that's open and scarce of other dino's, and park far away. Run up near it, but crouch before getting too close. Always stay behind it's butt, and crouching. If it turns, turn with it, staying behind it. 6 or so pets should do the trick, I have dogs ranging from lvl 20 to 140. Go for the highest level you can find, and ALWAYS stay behind it. After tamed, fly out w it to your base with the Pt. Good luck, and may the odds be ever in your favor.