Tamed passively. As soon as it eats your dropped honey, approach and ride it. In order to build up the taming meter, continuously press the indicated direction key (left or right). Don't click it just once, but press the button as long as it's green. Stop once the arrow turns red and wait a moment. Be careful when it throws you off. Wearing ghillie helps. When thrown off, you have to lure it again with another piece of honey to continue.

More Andrewsarchus Taming & KO Tips