If you're ever strolling through redwoods, make sure you're dinosaur is on aggressive so they can attack the Thyla. And if your emotionally attached to your shoulder mount like I was, make sure it's on passive flee to it can run away.
So after hearing about things in the redwoods that take you off your mount I went flying about for literally days with no issue what so ever, I’m thinking what’s the big deal? I start hunting for some prime meat and hide to take back to base in time for imprinting and suddenly out of nowhere I’m flying backwards off my argent and am chomped by this guy, lvl 10, I fight back and get released, I am lvl 98, tho I’m quickly killed before I can draw my mastercraft crossbow. My only imprinted bird and my xbow are now with my corpse near the edge of the redwood. My lvl 220 spino munched the tree hugger and I got my bird back after a second trip back to search. Moral of the story, these guys are legit savage and need be tamed ASAP
Best tactic I've come up with is to (double check before entering red woods) have your flyer following you and on Neutral/Attack your Target. When you're pounced off your mount, use a melee weapon in quick slot 1 (sword works perfectly) while your flyer backs you up in a few seconds, you'll almost certainly make it :P
I was going over the mountains and through the woods to my grammas house and litererally got shredded to pieces. Got killed again trying to get my stuff so than I couldn't find that location again...bout a week later I stumbled upon my argent that fortunately was in passive mode and fled from my killer.