Allos stay alone until another allo gets close enough. When an allo finds another allo they will join forces and form a pack. The highest level allo becomes the leader once the pack reaches a size of 3 allos. A pack of allos will always follow each others no matter what. They usually follow the leader, but can follow a different allo if say a player calls over that specific allo to follow him . If they wander too far from each other the bond will be broken and the allos will set off on their own until they find each other again or other allos. Once a pack reaches a certain size the allos will stop accepting other allos in their pack. The same goes for tamed allos. Once they reach the max pack size of 15 and more allos are introduced your original 15 allos and the new allos will form different packs. Hope this helps you understand allosaurus pack behaviors. Thanks for reading.
Fun Fact: Allosaurus had a bite force no better than a lion, but it could gnash it’s prey, instantly killing them. It was around the same power as the T. Rex’s bite force, so the gnash ability in ARK is super realistic!