Make a 3x3 stone floor surrounded with 2*height double door frame. This will make a cage that you can enter and get out simply but not the therizino. Then add some rams/stairs leading into the cage. Lure the therizino into the cage and knock it out easily with tranquil arrow. This cage trap can be built on a raft as well.
Its the most aggressive herbivore, so be careful ! It's a classic knock out and it eats berries or megalosaurus kibble which I really recommend because the tame takes a veeery long time. It also loses torpor quite fast so you're gonna need a lot of narcotics. But once it's tames, you got a real beast: it can mess up against the rex and is a farming machine. Leftclick for wood and thatch, rightcklick for fiber and "c" for berries. It's the first herbivore that harvests bodies: leftclick for meat and hide etc. And "c" for only hide. You can increase the amount of gathered ressources by leveling up, similar to the moschops.
Get on a rock that’s high enough that it can’t reach and too difficult to get on by yourself (with the use of jumping or any flying creature) then tranq arrow it until if goes unconscious, if you can get up on the rock easily so can any creature (this works with any aggressive creature that will attack you if you attack it) u p v o t e so people can see this tip
Make sure you hold it in quetz arms or taming pen because it does a lot of damage, lvl 105 did 135 damage before tamed. Uses not that much torpor but stay alert! Normal KO strategy. Mid-end game tame, usefull early game but hard to tame!
Best way to tame or kill is stone battlement and crossbow. Steps. Build stone battlement. Arm crossbow with desired ammo. Build ladders to top of battlement. Climb said ladders. Take aim and fire. Easy. Just be careful not to fall off the battlement. Don’t say that I didn’t warn ya.
As a low level or beginner who isn’t up to par with materials or leveling to fight these brutes, I have a simple trick!
First, strip completely naked and put all your items into a tame’s inventory.
Then, run up to the asshole, and punch it. Let it follow you, AND DONT TURN AROUND! Lead it far away from your base until it or something else catches you.
Respawn, and done! Rinse and repeat until you can kill it!