Der3Al3arab

Actually bosses don't ignore specific dinos but they target the biggest tame in the arena first so if you have deinonychus (which is classified as small) or a shadowmane (classified as medium) and a yuty (classified as big) the boss will ignore them all and go for the large size classed dinos in this case the yuty and will ignore the smaller ones (deinonychus, shadowmane...) even if those smaller are attacking it as long as the larger Dino didn't leave the agro range of the boss, this doesn't apply on player bosses can ignore you Dinos when you are close enough to him