I've found 2 or 3 while playing ark.
I've found 2 or 3 while playing ark. They usually spawn in very dangerous areas such as the swamp or survival island(carnivore island). Best thing to do is to build a pen around them, but don't take them too far from where they spawned. They will despawn shortly after. I should know. I've accidentally killed one, then found another, brought it to my base, then a while later it despawned. Hope this helps and happy hunting!