Huge pain to tame. I suggest making a 2x2 trap 2 high with a ramp, use rare flowers to aggro the Gali into chasing you into the trap.

You could also use just a bear trap but something else might trigger the trap because everything around you will get pissed at you.

Do not even try chasing these buggers, they will run at high speed and will usually run straight into the mouth of a hungry Rex.