You cannot knock these out don’t try you will just kill it I advise to take a megalosaurus and pick it up and put it and a stone two by six with walls three high and ceilings Then put a Dino gate on one side and feed it through the walls. GL happy taming
Easiest and safest way to tame this is to lure it under water. They stop aggro and you can tame as you please. Just make sure you come up for air every once in a while. Also be sure the water is deep enough.