An easy way to tame the velonosaur is to make a boomerang and agro it. When it tries to shot you run up to it making sure your under flaps and spam throw the boomerang aiming to the ground so it will come back faster. If it switches to melee simply walk away till it switches back to turret mode. With that done you can continue boomerang spamming.

More Velonasaur Taming & KO Tips