Buzz
A few weeks ago, I rewatched Jurassic Park, and from the plot to the visual effects, it still holds up remarkably well. Yet, there's one detail that's stuck with me since the first viewing—something that's deeply embedded in our cultural understanding of dinosaurs: the claim made by protagonist Alan Grant about the Tyrannosaurus rex's vision and what it can and can’t detect.
In the iconic scene where the T. rex escapes and threatens a group of humans, Grant tells Lex, “Don’t move. It can’t see us if we don’t move.” Sure enough, the dinosaur approaches them without noticing their presence right after that line. Interestingly, Michael Crichton, in the original Jurassic Park novel, elaborates on how the amphibian DNA used to resurrect the dinosaurs impaired their vision centers. Unfortunately, Steven Spielberg and the film’s writers missed a major opportunity by not including this explanation in the movie. As a result, Grant’s statement seems more like an established fact about dinosaurs.
Sci-Fi vs Reality
No, he's not. In recent years, paleontologists have shown that Dr. Grant was mistaken. In 2006, Kent Stevens from the University of Oregon conducted an experiment based on that very scene to determine the binocular range (the area both eyes can see at once) of the T. rex. The wider the range, the better an animal’s depth perception and ability to detect motionless or camouflaged objects.
Stevens created a scale model of the T. rex’s head and inserted taxidermic eyes inspired by the eyes of three animals closely related to T. rex—alligators, ostriches, and eagles—and tailored for environments that dinosaurs would likely have faced. As he explains on his website, Stevens employed a method known as “inverse perimetry” to determine whether a given object would be visible by checking if there was an unobstructed view of the pupil along a direct line of sight, and then mapped the field of view of the model.
Stevens' findings suggest that the T. rex had a binocular range of approximately 55°, which is better than that of modern hawks and eagles. And its vision would have improved further. Fossil records show that over time, the T. rex’s eyes became larger and its snout grew narrower and lower, providing even clearer sight lines than those predicted by Stevens' model.
For more about dinosaur vision, check out Stevens' web page and his study. For other JP inaccuracies that drive dinosaur enthusiasts crazy, take a look at this Wikipedia list.
