Could T-Rex's Really Not See You If You Didn't Move?

[00:00:00]In the immensely popular movie Jurassic Park, there's the famous scene where the giant T-Rex is attacking a Jeep during a thunderstorm. As it attacks, Dr. Alan Grant, self-respecting paleontologist, yells, "Don't move! He can't see you if you don't move." Here's the thing, that's wrong. If that comes as a blow, you're definitely not going to want to learn these shocking truth about Velociraptors that we're going to be getting to in the bonus fact section.

[00:00:26]The Tyrannosaurus Rex not only could just see fine whether the object was moving or non-moving, which helps one not run into a huge number of things that exist in the world. There's also quite a bit of evidence that the T-Rex's sight was extremely good, very possibly better than modern-day hawks and eagles.

[00:00:41]This is perhaps unsurprising considering that birds are cellular Sauria theropods, which is the same subgroup that the Tyrannosaurus belongs to. In fact, one of the T-Rex's closest living relatives is actually the chicken. Going back to the film, this non-moving fact from the hit 1993 movie inspired a good deal of research into the subject afterwards. Professor Ken Stevens at the University of Oregon began the project Dynamorph in 1993. [music] His goal was to develop a means to create scientifically useful yet simplified digital models of dinosaur skeletons.

[00:01:13]Using digital technology, he wanted to recreate tangible visualizations of extinct animals including the T-Rex.

[00:01:20]After speaking at a conference in Toronto in June of 1993, the movie was released in the US on June the 11th, 1993. He paid a visit to the Royal Ontario Museum where he met with North America's leading paleontologist, Garfield Minott. He was working on a life-size reconstruction of a Tyrannosaurus Rex that provided Stevens with the lifelike head sculptures of seven different theropods, bipedal and primarily carnivorous dinosaurs including a T-Rex and Velociraptor.

[00:01:47]Using these models, a laser pointer, a glass plate, and taxidermic glass eyeballs, Stevens performed experiments to determine the visual field, depth perception, and binocular range, the area that can be viewed at the same time by both eyes of these dinosaurs. He published the results in 2006.

[00:02:04]Performing a test called inverse perimetry, Stevens evaluated how well a T-Rex would be able to see objects at various elevations and shapes. To quote him, "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." Stevens determined that a T-Rex's binocular range was 55°. Which is wider than even hawks. Stevens continued the research with other theropod dinosaurs and determined that most theropods had binocular ranges at least similar to modern-day raptorial birds, aka birds of prey. Another recent discovery also confirms that vision was an important sense for the T-Rexes.

[00:02:42]Scientists determined that the T-Rex's snout over time gradually grew longer and narrower. Cheekbones dipped more inward and their eyeballs grew bigger.

[00:02:51]While structurally, the T-Rexes' head and eyes seemed primed for great vision, the question still remains, well, how good were their eyes really? For that, Stevens took the known optics of distant relatives of the T-Rex, including the eagle, chicken, and crocodile and plugged them into the larger T-Rex eyeball. He was trying to determine visual acuity, clearness of vision, and greatest distance an object can be seen that still remained distinct. According to his findings, while admitting that these were best-case scenario determinations, the T-Rex may well have had a visual clarity up to 13 times better than a modern human. For reference, an eagle has about 3.6 times the visual clarity of a person.

[00:03:29]Additionally, it was determined that a T-Rex's vision allowed an object to remain relatively clear up to 6 km away.

[00:03:36]For humans, it's only about 1.6 km for the same clarity. As Stevens put it, "With the size of its eyeballs, the T-Rex couldn't help but have excellent vision." Of course, in the movie, and to a greater and more detailed extent in the [music] book, it is stated that in order to bring these dinosaurs back to life, the scientists needed more DNA to fill the gaps. In the book, they decided to splice dino DNA with bird, lizard, and frog DNA. In the movie, they only use frog DNA to hammer home the plot device that certain species of frogs [music] can change sex when there is significantly less of one sex in the wild. So, given this, it may be the dinosaurs in the movie are more frogs than actual historic dinosaurs. So, if that's the case, while a bit of a stretch, the question that can be asked is was the statement made by Dr. Grant in the movie actually more about a frog's vision than a T-Rex's? Digging a tad deeper, this quote from the movie by Dr. Grant gives us a clue to what species of frog they may have used. They mutated the dinosaur genetic code and blended it with that of a frog's. Now, some West African frogs have been known to spontaneously change sex from male to female in a single sex environment. The most common West African frog that has a tendency to change gender is the African reed frog. These frogs see quite on par with other species of frogs with their horizontal pupils, although they cannot see in the red spectrum. Yes, it is documented that frogs have a hard time seeing prey that doesn't move, but not significantly so such that they'd be blind to the prey. Plus, humans and really all other prey do move even when they think they are standing still, breathing, trembling, involuntary jerks, this is all in movement. Additionally, as Kent Stevens said in a response to this moving myth question, if you're sweating in fear 1 in from the nostrils of T-Rex, it would figure out you were there anyway. Besides great vision, the T-Rex also had a great sense of smell and had good hearing. In fact, their large olfactory bulbs and nerves relative to their brain size indicates they may have had a sense of smell about equivalent to modern vultures which are able to smell dead things from as far away as a couple of kilometers. So, whether scavenging or hunting, the T-Rex was good at finding things to eat. That said, there is some debate as to just how fast they were with most scientists today thinking they only had a max speed of about 70 to 25 mph. In the film itself, the character of John Hammond states, "Well, we clocked the T-Rex at 32 mph." Even at that speed, it would have made the Jeep chase scene quite a bit less dramatic than what was depicted. Let's get into that bonus fact. If you thought Velociraptors were slightly bigger than a human, reptilian-looking, hunted in packs, were found in what is now the United States, were ridiculously intelligent, and had a thing for Chris Pratt, well, literally none of that is true except for the last one. I mean, who doesn't love Star Lord?

[00:06:24]In truth, Velociraptors were actually only about the size of a domesticated turkey, being about 3 ft tall and 6 ft long with most of the length coming from the tail, and they weighed in at about 20 to 30 lb fully grown. More than that, they also looked somewhat like a turkey as well, but with a long tail. It turns out that Velociraptors were very similar to birds in a lot of ways. They had hollow bones, feathers, they built nests for their eggs, and are thought to have behaved very similarly to birds. As Mark Norell, curator of fossil reptiles, amphibians, and birds at the American Museum of Natural History stated, "The more we learn about these animals, the more we find that there is basically no difference between birds and their closely related dinosaur ancestors like Velociraptor. Both have wishbones, booted their nests, possess hollow bones, and are covered in feathers. If animals like Velociraptor were alive today, our first impression would be that they were just very unusual-looking birds. More than that, it's generally thought Velociraptors were solitary creatures rather than hunting in packs as depicted in the films. Next up, the Velociraptor was not found in the United States as the film suggested where the paleontologists in the film dug up the Velociraptor skeleton in Montana. In fact, they are typically found in Central Asia around Mongolia. So, were they intelligent? Well, for a dinosaur, it's thought they were somewhat intelligent due to their brain size relative to their body size, but it's not thought they were particularly intelligent overall, and certainly not smarter than dolphins, whales, and some primates as Dr. Alan Grant in Jurassic Park 3 suggests. So, [music] what were they thinking in Jurassic Park? Well, basically, they modeled what they called the Velociraptor in the movie after Deinonychus. The Deinonychus were also raptors, but were significantly bigger than Velociraptors, coming in at about 12 [music] ft long and about 6 ft tall and weighing about 150 lb fully grown.

[00:08:12]Pretty much picture the Velociraptor in Jurassic Park, and you get a good idea of what [music] these dinosaurs were thought to have looked like, although they also likely had feathers. The Deinonychus also were thought to have occasionally hunted in packs to bring down larger prey and were thought to have been very fast. Their habitat was also in the forests of North America. On to the intelligence bit, they were also not thought to be very intelligent compared to dolphins, primates, and the like. However, clearly they were smart enough to work together to bring down larger prey when the need arose. As to why the Velociraptor name was used even though the creatures were loosely based on Deinonychus, according to Michael Crichton, this was simply because the word Velociraptor was, to quote, more dramatic.