Start with a two by three foundation, either side have stone Dino gates, on the sides have stone door frames 3 across and three high with doors in the gaps at the bottom. Use wooden ceiling on the top as the attention of the Dino will be on destroying them first. Once built lead the Dino into the trap,run out through one of the side doors and loop to the back and shut the Dino gate, rex is done for, shoot the living **** out of it until it is ko. Spiked wooden walls will be needed as it falls out the side but this is an extremely effective method. Works with pretty much any Dino including birds but obviously not including gigas, you need metal for that sheet. Hope this helps and good luck ;)

With an argy you trust, fly out of range and shoot it from afar with tranq arrows from a crossbow..this is best done when the rex is feeding because it won't notice the arrows in its ass...you will know when you are out of range because you will have to aim over the rex when you fire to actually hit it...

Get on quetz and have a buddy in the back and fly low and he will follow ur bud in the back while he continues to shoot him keep in mind rexes do run away after a certain amount of shots so have it close to big rocks to get stuck on if not get some gates n trap it or do a hard core way with a turtle/doedic with high health and saddle and keep getting hit while ur tribe shoots the Rex works great

Taming these amazing dinos is pretty easy, as they are slow and don't bits as fast as a spino. If you have a Bird with 2k health or more you can use it to tank the rex and shoot tranq arrows. Or if you have 126% speed you can just run and shoot (which is what i do). if you're at a place with q lot of Rocks i would suggest running behind the larger Rocks and then tranq. Once it's down you shouldn't have to wordt about anything as their torpor drops very slowly and nothing But allos attack them when their down. When you get a 110+ put your first points info health until 15k, then 2k stam and the rest into melee and you have yourself a alpha Slayer.

I myself have leveled my movement speed to 138 which is able to outrun wild rexs even raptors and a lot of other stuff. And I did that for the sole purpose of taming stuff like a rex cause I just shoot it 1 time then reload as I'm running then just repeat till down. It's actually easy to solo tame one if ur movement speed is high enough. And you only need 125 speed to out run a rex so if your tribe is looking for Rex's but not on a lot like you are do this and an easy solo tame with enough resources