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.
I found out that Allosauruses gain an attack bonus against large creatures. I found this out because I was using my level 220 Allo to hunt and I targeted a Diplodocus and the damage was meant to be about 125 but instead my Allo was doing about 550 damage. I then made a theory that anything larger than an Allosaurus will take additional damage so I then tested this theory on a Paracertherium and my Allo did additional damage. I can confirm that Paracers and Diplos take additional damage and I think it applies to Brontos aswell because I saw a low level pack of Allos take down a high level Bronto so it would be reasonable to assume that it works. I have never seen ability said anywhere so I thought I should mention it. Theres also a pack ability where if there is at least 3 Allos then they will gain a pack bonus which will give the leader (the highest level of the 3) an additional attack which inflicts a bleed effect. Hope you found this helpful.
The Allosaurus is a pack-hunting theropod that's smaller but faster than Rex. When in packs of 3 or more, the highest level Allosaurus will become the pack leader, emitting a red aura and making it stronger in battle.~Steel Cookie 123