The MOST effective and EASIEST way to tame a therizino is to use 4 METAL bill boards which is cheap to make. Make a box form with 3 bill boards. Have it follow you into it. Carefully place the 4th one to complete the box 💢 somewhat like that 👈🏽 And it’s trapped. Then tranq and tame it. No major farming of stone, no major building structures. Quick and to the point. Small gaps don’t matter just make sure it’s close enough that it can’t get out.
Pro tip: kill everything in the area and make sure nothing hits it. Do not let your guard down the game will spawn random stuff in if you do and in the blink of an eye you now don’t have a perfect tame and may lose kibble if it gets killed.
Use 4 bill boards (metal ones) put 3 in a box form and have it chase you in there using a high health argy. Once it’s in the square very carefully place the fourth bill board, small cracks don’t matter it won’t be able to get out. Big gaps may get you killed. If that happens just grab your stuff again and try to get it in better. Make sure to bring extra bill boards in case you screw up. Then once it’s stuck tranq it and proceed to tame. Be careful with other predators, for some reason any time I go to tame something, the coast may be clear but, something always spawns to try and ruin my taming effectiveness so be alert for any nasties and kill them before they hit your knocked out tame. The metal bill board method works with allosaurus and Dino’s of that size generally.