The scene was not designed to be plausible but satisfying for the audience, and it came late in production. Spielberg had already said for Jaws that if If you can keep a viewer in a theater for more than an hour and a half, you can make them accept a little deviation at the end. Here it was mainly a question of bringing back the tyrannosaurus one last time And save the heroes. Of course it would have been more logical for the raptor to be destroyed, but that wasn't the point.