Yeah, that's got me wondering if the iRex is acting like a queen or leader. driving all the other dinosaurs to stop being so relatively docile (especially since we see one of the semi-tame raptors attacking a guy).
That would be utterly terrifying. Ever been at the aquarium when a shark decides to take a run at the glass for whatever reason? That's enough to make you jump, but imagine the Mosasaur doing that... Even if the glass/transparent steel/whatever doesn't break, I think I'd have a heart attack.