I didn't know about anyone else but be careful. My first encounter way by a river and one of these game out of the woods and attacked my Parasaur at same time a raptor worked with it and took me off my mount and killed me. Never thought I'd see two different species work together.
Me: let’s go get some fish!
Me: sees spino.
Me: oh no! Goes the other way.
Caro: zooms in from nowhere.
Carno: is speed.
Diplodocus: AAAAAAAAAAAAAAAAAAAAA CARNO FIGHT ME INSTEAD
me: thank you massive dino.
One morning when I woke up (in the game), there was a level 150 Alpha Carno standing just outside my base, it just ran through my defense, as was it nothing) and killed half of all my animals inclusive my lvl 192 raptor, these bastards will destroy you. A tip for other unlucky players, lure them away from your base, if possible.