Look if you can find one, who got stucked in a tree than try to knok him with some torpor arrows. But he needs a lot of narcotic. Look that you collect enought ore the better way: if you w8 until he got tamed take a parasaur and collect some berrys. Hope it helps you.
Pro Survival Tip:
Wild:Actually these damn things are terrifying animals but actually they are herbivores(a type who eat plants)if you want to tame it wait until you have tranquility weapons and so many biotoxins(they are found in cyan-bright jellifishes swimming in the ocean) and keep it in a pin or just ignore it if you're a low leveled player they won't hurt you if you don't get near them they are aggressive but they are peaceful if you don't get near them that's why they don't kill parasaurs or dodos nearby if they see them. I know that these things usually are in pack of 2-4 I've been killed by this once accidentally slides in a cliff and stopped by this thing and now I ran away but still I'm caught because they are fast.
Domesticated:After Hours of pain of taming this Theriznasaur using tranq and Bio Toxin you finally did it this things are Apex Killers and very fast will terrorize Other Dinosaurs or possibly PvP.If you have a saddle it can gather all resources you want.
They're almost impossible to tame, however definitely a must have, makes farming so much easier, even without saddle...
Set it in wandering, and wait jus few minutes, and you'd get tonnes of everything, including berries, wood, and even meet, without even knowing that it attacked some preys...
To get wood, use normal attack which is slashing with claws. To get berries, use bite attack. To use bite attack on mobile, change multi tap to alt attack 2 and tap with 2 fingers when riding the Therizinosaur. To get fiber, use the tickle with claws move. To use the tickle with claws move on mobile, jump when riding the Therizinosaur. Upbote so people can see!!!