Taming it is fairly easy. First they are unique passive tame. They do take rockarots as the second best feed from troodon kibbles. Thou the type of food you feed them doesn't affect the taming effectiveness, it's best to use their preferred food to reduce time spending on their back taming it. It's effectiveness depend solely on how many times you fall off its back. So, get sneaky and sneak up on them, put food in 0 shortcut slot. feed them the first one and move closer to ride. Look at the bottom left of the screen. When it promts to be fed again, press e to keep it calm. Beware, pressing e when it does not want treat will unmount the tame and you will lose effectiveness by a lot. It is recommened to use quetzel to bring it to your own taming pen. During the tame it will run pointlessly in any direction and may run into predators if taming in wild. If you happen to do so in the wild, take another tribe mate with you to take care of the surroundings.
Feed it then mount. You won't be able to control it until the tame is done, dismounting appears to lower taming effectiveness so make sure you have a good supply of carrots (preferred food) on you. When it starts to buck you off you have to hit enter to feed it again. If you pay attention to the bottom left corner of your screen there will be a tool tip that will pop up when you can feed it abs just before it starts bucking.
These guys are easy to tame low level but a 150! The tame percentage drops as the horse runs do good luck ever taming a high level one. Unless! You knock it out build a box around it wait for it to wake up and the tame to your hearts content. Vote up to help others!