Taming one won't be easy because if you fight one and there is others around they will kill you. So first check if there is no other ones. Then if it lands on the around quickly bola it and knock it out with a tranq arrow 1 time or with a wooden club. And give it the amount of fish the dododex says.
Yeah.. I don't recommend attacking them except tame em I had two one a level two and the other one is level three when I went out on my flyer I was getting stam and a t rex came up behind me and I just see at the top of my screen "your dimorph level TWO AND THREE killed a level 30 t rex I was so confused like what how????