My all time favorite mount!! Find a high level and make it yours.

Add the points to health, stamina and the rest in attack and he is good to go.

Tip for taming one:

Build a taming pin (at least 3 high), get your argy (or other flyer) and find the thyla you like. Shoot it 1 time with a tranq dart from enough distance so it will fall out of the tree without killing you, hop on your argy and pick the thyla up when he's running towards you and drop it in the pin. Tame it with cooked prime meat (they prefer cooked) and there you go! BTW, make sure you have enough narco to feed it while it's taming.