If u just started ark and tamed some dodos and see a rex rushing at u just grab ur dodo and yeet it at the rex and run

If you run into one of these, stand perfectly still. Rexes can’t see you if you don’t move. I saw it in a movie once.

Since when can Rex's climb cliffs like spider man

Bring a wooden club and a dodo

When encountering a rex make sure u have a large-ish tame because small tames like raptors or wolves will get stunned and u will be unable to ride them for a couple seconds.