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
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.
They're so annoying to deal with. Those things will rip through your flesh so quickly and never seem to have the will to be tamed as I found that out of the 50 I tried knocking out(Primitive Longneck) for an "experiment", 34 died.
They are also aggressive so... Yeah.
I found that the best way to kill one is to have them trapped in bollards or spikes and have X plants shooting them. DO NOT get in melee range unless with a rex, spino, giga, or another therizino. Most of the dinos I listed(all but giga) should have relatively similar levels or you risk losing them. I also seem to find an infestation of them wherever I go.