Dinosaw it. in Chunky giblets

So I finally got around to seeing Jurassic World last night. It was fine, pretty good actually, but can someone explain something to me? Why is it that the dinosaurs, whenever there’s a shot from behind, they have no assholes? Is this something about dinosaurs I never knew? Go watch that movie. Whenever you see a dino running in front of the camera, have a look for it’s asshole. It has no asshole! What the fuck?!?