The easiest way to tame is to bring a high lvl Argie, a spyglass, some food, and a crossbow or longneck with tranqs to carno island. Kill everything near the Rex including all of the lower level rexes, leaving only the highest level Rex. Then, aggro it and fly up to the center piece of the island and find a safe perch to dismount. Shoot it from there, and when it runs away get on the argie, fly closer, land, dismount, and continue shooting until it is too far, then remount and repeat. Once it is tranqued, get some prime from whatever is near, and put it in the Rex. Take your argie and fly it above the Rex, and just keep an eve out for anything that might attack it. Once it’s tamed, cryopod and fly back to the nearest allied base. You can repeat this and get a different gender, and begin building up an army. Fair hunting a good day to you.

It's usually takes about 10 to 30 tranq darts to knock out a rex so you shouldn't use tranq Arrows unless it low level and desperate. And it also takes 10 to 100 narcotics to keep it asleep until you tame it

The easiest thing to use to tame it is prime fish 🍖.

So get a shark first and finally the best tip of always over prepare and use more tranq darts than necessary.

The best place to find a Rex is on the volcano in the middle of the map.

So, in the story of Atalanta's death you will see we tamed our first rex. This is how we did it.

Just find the rex. Don't engage just see where it is and locate any near predators. The make lots of tranque arrows and narcotics(narcoberries will do fine.). Make a crossbow. Then go and fight the rex. Wait for it to attack a big herbavore like a trike. Wouldn't suggest a parasaur because if you hit it it will run. We had it fight a steggo. Stand and shoot it in the butt and hope it won't see you. It shouldn't run too fast but it will disapear in trees. Once it's down watch its torpor. Once tamed, enjoy!

-Jedi

I just tamed one in single player and it's easy

Just build a stone trap "4 foundation and 16 doorway frame with 4 wood ramp" then bring the rex in it and shoot tranq arrows then put narcotics inside it's inventory with raw meat. Just make sure to feed it narcotics time by time. Boom there you have a rex. I saw it in Glock9 video

For ppl that say you dont need trap, movement speed is a waste of level points because you’ll have a mount anyways so upgrade health and wait, use extra points for melee, movement, oxygen, after you have 800 weight and 1k health. Trust me i made the mistake

Its more fun to fight than runaway