First, for low levels, I suggest finding one that is stuck in between two trees which is surprisingly common. I used a crossbow, but you could just use a bow. Craft tranq arrows. Shoot at the belly, and try to do it quickly before it can get free. I suggest 4-6 tranq arrows, maybe more for a higher level. I brought a few narcotics just in case, but I didn’t use any so you don’t necessarily have to. Bring about 20-40 berries, probably more, and you’ll most likely have extra. Put it in the triceratops’s inventory and wait (in my experience it went up by 2%, so make sure you’re ready for a wait). If you leave it’s side the taming will still go up. After it is tamed, name it!
Extra: bolas will NOT work, if you use them they will start to attack.
Uses: they can be extremely strong (I have seen a group of 2-3 trikes kill a sarco, which is a much more high-level tame). Once a saddle is crafted, they are not very fast but they do collect thatch easily from trees as well as short amounts of wood. They get much more berries from a single bush than you can. They do not jump when you’re riding.
Thanks for reading! Sorry it was so long. Please up for the noobs to see! And of course, have a nice day.