Would a T-Rex see me if I stood still?

By Rhys L Griffiths

“Don’t move, he can’t see us if we don’t move.”

We’ve all heard these words muttered by Dr Alan Grant as the T-Rex break free from it’s enclosure and starts sniffing around the jeeps. That is unless you’ve never seen Jurassic Park and in which case, stop what you’re doing and go watch it immediately!  But what if Dr Alan Grant was wrong? A ludicrous idea I know, but how did a T-Rex see?

Well after the film came out in 1993 a researcher at the University of Oregon, Professor Kent Stevens, began a project called DinoMorph with the goal to develop “a means to create scientifically useful yet simplified digital models of dinosaur skeletons”.  By doing this he was able to map the binocular field of view and depth perception of certain dinosaurs, including the Tyrannosaurus rex.

In order to do this, Stevens reworked a technique used to measure and assess visual fields and using a glass plate, a laser pointer and taxidermic eyes, he was able to estimate whether certain objects can be seen at different elevations. Publishing his results in 2006, he claimed that the wider an animal’s binocular range is, “the better its depth perception and capacity to distinguish objects – even those that are motionless or camouflaged.”

The main indication that the T-Rex actually had good eyesight is that both it’s eyes are forward facing in a narrow skull meaning there would be an overlap in the fields of vision giving it some sort of depth perception. Through Steven’s research it was determined that most theropods (2 legged dinosaurs that include the T-Rex) had binocular ranges similar to modern day birds of prey. But in order to get an idea of how clear the Tyrannosaur’s vision was, he took the known optics of extant animals with different seeing abilities, such as alligators, ostriches and eagles, to help make his estimates more accurate. From this he estimates that the T-Rex had excellent vision being able to keep objects relatively clear up to six kilometres away, compared to Humans which is about 1.6 kilometres.  With three inch eyeballs, dipped cheek bones and a long narrow nose, best case scenario sees the Tyrannosaur having visual clarity up to 13 times better than a human.

So where did this motion based eyesight myth originate from?

Well there are some species of frogs that can’t see in the red spectrum, meaning they have trouble seeing their prey when it’s not moving. Not to the extent that they are blind without the movement, it’s just not as clear. In the book of Jurassic Park (and briefly in the film) it’s mentioned that in order to bring the dinosaurs back to life they needed to fill gaps in the DNA so they used DNA of frogs. So if you ever find yourself face to face with a T-Rex, staying still may not be the best idea.  You could try running, however that may not be such a great plan either. Read ‘Could I Outrun a Dinosaur?’ to find out why.
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Posted in Biology