Just shoot it with arrows while its killing stuff. Make sure you dont get killed while shooting it on the ground and try not to knock it out while its killing something that will kill it if the rex falls asleep. Not a lot of stuff tries to attack a rex for obvious reasons so you should be fine not putting protection around it like spikes or walls. Just bring a flier just in case it starts running at you. They have a short attention span and have bad mobility. I recommend using kibble as it wont take as long and will give it a level boost.

How to tame a rex

WHAT YOU NEED: a ton of tranq arrows, a ton of meat, a pternodon with saddle (2 players) or a quetz with platform saddle ( single player) and a crossbow

HOW TO DO IT MULTIPLAYER: pick up your buddy, armed with a crossbow and tranq arrows pterno, fly over to rex, tranq it a ton till it gets knocked out note they'll run away at high torpor, then feed, you'll need loads of meat + narcotics, be ready. HOW TO DO IT SINGLE PLAYER: literally, just go on quetz platform an shoot, once you knock it out, of course you gotta feed it!

Good method is a decent thylacoleo,cause he's a bit tanky,can reach places than the rex cannot,and you can shoot when mounted,IF not latched to a wall with it.

Also quite useful to kill everything around your unconscious rex and collect prime meat in a pinch.

Remember to bring extra supplies and put down a bed in a safe place in case something goes wrong!!

Easy tame.... Just make a 2x3 stone foundation and cover 3 high with doorframes on the sides. And 2 high on either end. Place wooden ramps (They're temporary but easy to make and repair) just get aggro and run inside the trap. Takes about 30-45 tranq arrows from a mastercraft longneck. On mobile the kibble is easy enough to make. Get a fast mount with knockback. Go to fars peak and run around pulmonoscorpions to find their eggs. The kibble needs prime jerky and longrass so if you have that set up, rush a few caves give it a soothing balm and under level 70 only needs one kibble. So that's a convenient benchmark. It's expensive to build the trap big enough to get the red out so once tamed just request it back to base. Unless a Giga or enemy tribe shows up it will be untouched if left alone.

Whether you want to tame or kill this strategy works. You need four people two Tapejares. Two people fly two people get on the back and shoot it. one person circle the Rex and one rests swap out now and then so you can keep you stamina up, or if you feel bold both circle it and shoot it.

So I see all these tips on how to tame a Rex. I was able to tame one by standing on a cliff and using about 40 tranquilizer arrows. Once it starts to run away, DO NOT BE AFRAID. Just chase after it and keep shooting it. IT WILL NOT CHASE YOU (at least it never does me). Once it becomes unconscious, dont just use any meat. Use Pulmonoscorpius kibble. I only needed 3.

The Rex said that the torpor rate I drop is high. I disagree. I have tamed two rexes with raw meat and I did not need to use any extra narcotics or narcoberries. All u need is a bow with around 40 to 50 tranq arrows, and meat of any kind. Find a rock that is high enough for u to shoot the Rex and knock it out,