I got DESTROYED by a mate boosted level 125 while wearing Ascendant & Mastercraft Flak Armor (1500 Total Armor). Avoid these on foot at all costs. If your character doesn't have high movement speed, you probably won't survive. The Ark Freddy Krueger
These guys are aggressive up close, also don't hit them, all other therizinosaurs near will help out and attack you. About 5 therizinosaurs killed my pteranodon because I accidentally hit one and was low on stamina. Just don't get close to this guy if you are new.
SNEAKY as hell. I had 3 of these bastards (seperately) try to attack me and my mounts. Very common on cliffs so do not perch a flying mount there for too long. They will quietly slay yo ass. Also, be careful on beaches, they frequently camoflauge between trees and then animate when you walk by, like it's YOUR fault.