Valguero aberrant area, specifically in the radiation zone now spawns aberrant versions of these guys. Up _vote so people can see!

A tip for beginners:
If you attack these guys with your dinosaur be warned...
Even during riding your Mount, they will kill you first, not your dinosaur…
And they do tons of damage and are not that easy to hit with smaller dinosaurs (small hitbox)
Try to avoid them early game

Quick hint, leave small packs of these guys alone, or you dead.

If you accidentally hit one, get on a pteranodon and barrel roll until the hole flock dies.

Don’t underestimate them. They can kill Rexs easily by exploiting the turning radius and hit the rider on mounted creatures.