If you have a tribe-Have a friend carry you on an argentavis, and shoot it till it goes down.
If you're alone- you can: make a trap out of wood or stone with a bethemoth gate with a box inside so you can shoot it safely.
Or you could: make a ballista and a chain bola to subdue it then shoot it down.
Or wildly shoot it and run and hope for the best :)
I have figured out a new way to tame dinosaurs cut off the dinosaurs meat wise in the area try and keep the dinosaur in the area and send a dodo bird out to attack the tea Rex with bunches of Botox in and it had the tea Rex eat the Botox and it’ll knock it out you go feed it meet make sure you have plenty of Botox in and you’ll have a pet your ex and no I would not recommend trying this whenever your level one side effects may be dead dodo bird hey might find you and run but seriously You better find a good hiding spot