If you want to tame, all you need are 15 tranq arrows, a bow, crops/berries, 80 bio toxins and a tank tame (optional).

First, if you brought a tame with a lot of health, place it near the theri on passive mode and run. Once the theri sees your tame, it will start attacking it, hence why I said to bring a tank. Start shooting it with tranq while it's distracted. If you did this right, the theri will not go after you. Once it falls, the long wait starts. Load it up with rockarrots, berries, biotoxins (bc it's torpor falls very fast) and voila! You have a theri.

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