Easiest way to tame one: go find one(I found a lot near the blue obelisk), pick off carno's with argy. Place behemoth gateway and gate, open gate, behind behemoth gateway place another behemoth gateway without gate this time.
Place a third behemoth gateway with a gate closed behind the one you just placed. (Make sure behemoth gateways are close to each other, I mean... CLOSE!) Place large beartrap inside the trap, then lead it into trap. Close gate and tranq. When done tranqing wait for it to starve (bring narcotics just incase) last step... feed it. Now it is yours. (Try to bring an empty cryopod)
It really is that simple though, they can't reach you or your flier on a big enough rock, so if you don't want to make a trap you can just shoot down from a rock or cliff once the carnos are dealt with. Be ready for a goose chase once it starts running.
If you have Desmodus, attach to a wall and fire one dart. The UT will fear roar but you won't detach and you can wait it out. After, just fire away until he runs, then detach from wall and chase and shoot. Took me about 15 minutes of chasing but he didn't fear roar after he started running. Used this after traps failed me
How to tame a Yuty with 3 large bear traps, a longneck and some tranqs:
1. Locate Yuty.
2. Align large bear traps in a straight line (each one has a bit of distance in between) a good distance away from the Yuty.
3. Clear area of large creatures, as they may fall into the traps.
4. Wait until the Yuty and it’s carnos move in to attack something.
5. Shoot the Yuty with a tranq after it has roared. The Yuty will then chase you while the carnos continue attacking their first target.
6. Shoot as many tranqs into the Yuty as you can while running back to the bear trap line set before.
7. Yuty will run over and become trapped in the bear trap, allowing the player to pump tranqs into it.
8. Kill the Yuty’s carnos, who were far too late in their task of defending their master, and feed the Yuty the carno meat >:)
9. Name it Abunga
NOTE: technically only 1 bear trap is needed if you perform perfectly, however I like to have backups placed in case a trap or two are tripped on accident, or it takes more than 1 trap for the Yuty to knock out (the higher the level, the higher the chance this will happen).
In my opinion this is way more resource and time efficient than a traditional stone wall trap. Hope this helps! :3