Look out for them when traveling through the redwood forest, they sometimes spawn on trees and can jump, they dismount you from the dino and are dangerous to fight alone. Got dismounted by one from my argent, managed to survive but got separated from tje bird, took me 30 min to find it.
The redwoods are now basically a no fly zone, I lost a quetz, and a pter to these b******s. They jump out of the tree, rip you off your mount, and then pin you and your mastercraft armor to the ground and murder you.
They will jump on you and murder you even if you're on a fricking wyvern. You are not safe from them no matter what animal you have. Just accept your slow and tender death. I learned it the hard way lmao. Scared the fckng hell out of me
Wanna find one? Simply mind your own business flying through the redwoods and they'll find you! Just make sure you can take some fall damage and that your tame is set to passive so it doesnt kill the thyla. (I know this seems like a joke but this is legit the only way I know how to find them.)