Hello and welcome back to Mike of the Mesozoic! It’s been a while since the last post – it took me quite a time to really get to the essence of what I wanted to say about Jurassic Park‘s Tyrannosaurus rex scenes. T. rex is probably one of the best-understood dinosaurs in all of palaeontology, and therefore much that can be said about it. So let’s continue our adventures in affectionately analysing the movie through the lens of modern science, and get right down to it!
First of all, we’d better address the big, scaly elephant in the room, and tackle the feather controversy. This seems to be an emotionally charged issue for some reason, as if a forty-foot-long predator that weighed seven tons and had one of the most devastatingly powerful bite forces of all time could be made not cool by putting a feather coat on it. I’d better mention the news story that was circulated pretty widely this summer about the discovery of T. rex scale impressions, prompting newspaper stories that were largely variations on a theme of “turns out Jurassic Park was right all along, nyah nyah.”
(Image nicked from Biology Letters)
Well… maybe. It’s certainly possible that Tyrannosaurus was entirely scaly, of course. But can we say that for a fact? The impressions found were from the neck, pelvic region and tail of a specimen nicknamed “Wyrex” that was recovered from Montana in 2003, and I should probably point out how absolutely tiny some of them are – shown life-size, the impression pictured above would be a little larger than your fingernail. Some of the others are bigger – the largest is perhaps the size of a tea tray – but it’s important to remember that we’re talking about an animal that stood twelve to thirteen feet tall at the hips. I’m not trying to pooh-pooh the scale impression study in any way – it’s a very important and interesting development. I’m just saying that it’s important to remember that a lot of T. rex‘s taxonomic relatives were absolutely, definitely feathered in some way, and that we shouldn’t be surprised if it eventually turns out that it did in fact have a bit of feather action going on somewhere, or in the juveniles. What this means, of course, is that as far as I’m concerned it’s currently impossible to pronounce the Jurassic Park rex definitively right or wrong on the feather issue, and the movie depiction is at least as good a hypothesis as any you’ll find at the moment.
Less controversially, we can talk about eyesight. “Keep absolutely still,” Dr. Grant famously says in the movie, “his vision’s based on movement.” Which is unlikely, all things considered; Tyrannosaurus has what I believe is the largest eyeball of any terrestrial animal known to science, and I don’t even mean relative to its own body size. There’s really no reason to suppose that it wasn’t good at looking at things it might be able to eat. Rexy, as Muldoon calls her in the novel, has another eyesight problem in the movie, though; her skull is set up all wrong for binocular vision.
(Right-hand image nicked from Professor Kent Stevens’ website)
Jurassic Park‘s Tyrannosaurus head is boxier and wider across the snout than the real animal, and her eyes seem to be somewhat recessed in the skull, meaning she spends a fair amount of time looking at things off to her side and has great difficulty seeing around her own nose in the front. Her lack of binocular vision is even made somewhat obvious by the filmmaking itself, as the rex animatronic is forced to bring the side of its head to the car window in order to see the children inside (but I still think the dilating pupil is a really cool practical effect shot).
I always thought Rexy’s evil eyebrow ridges looked a bit silly and cartoony in the film, but I can’t really say a lot about them scientifically. The skull does suggest that there would be bumps of horn over the eyes and on the top of the snout, and while they probably wouldn’t look so stylised, nobody can say for certain that the movie is wrong – if Tyrannosaurus had brow ridges like that in real life, they wouldn’t fossilise, and we wouldn’t know.
I mentioned bite force earlier in the article, so let’s get to the animal’s mighty jaws. I have to give the movie kudos for getting T. rex‘s teeth pretty bang-on, by the way; tyrannosaurs have a very distinctive tooth setup, with short teeth in the premaxilla (the frontmost part of the upper jaw) and big, fat, banana-like teeth down the sides, which is exactly what’s shown in the film. I suppose it’s a little unusual that she appears to have a full set of gnashers – tyrannosaurs would lose and replace their teeth every few months, so you might ordinarily expect to see one or two missing in there. As for the power of the jaws – well, the best current estimate seems to be around 8,000 psi (pounds per square inch), and I believe the strongest living terrestrial animal bite is the nile crocodile’s 5,000 psi chomp. I wonder what the chances are that if a rex decided to bite a lawyer on a toilet that the poor chap would simply get chopped clean in half?!
Usually by this point in the post I’ve made some comments about the animal’s general posture, and today is going to be no different. The tyrannosaur’s hands are probably the thing that seems the most dated about Jurassic Park‘s depiction; I’m sure they were perfectly fine and accurate when the movie was made, but science has moved on. This is important, because JP continues to inspire all the popularly held ideas about dinosaurs. Ask anybody you know to pretend to be a dinosaur, and they’ll probably do this:
When, really, they ought to do this:
We now know that T. rex, Velociraptor, and all the other therapod dinosaurs were completely incapable of holding their hands in the Jurassic Park-y, palms-down fashion. Their wrists simply didn’t work that way, and should correctly face inwards as though holding a basketball or a bowl of soup. Such is the continued influence of Jurassic Park that just about every toy dinosaur in the world to this day continues to have Wrong Hands Syndrome. Please, friends of this blog – I urge you to call attention to these poor, crippled dinosaurs with their broken wrists…
Meanwhile, here’s a fun fact about T. rex: just like your Christmas turkey, it had a wishbone!
The Tyrannosaurus wishbone – or the furcula, to give it its proper name – has been discovered since the production of Jurassic Park , and in addition to being something you can get a really big wish out of, also represents a subtle change in our understanding of tyrannosaur anatomy. Now that we know the wishbone goes in there, that means it’s got to touch the coracoids (the big flat parts at the front of the pectoral girdle), and that means the shoulders must have been closer together than we’d previously thought. Therefore, Jurassic Park‘s Tyrannosaurus ought more correctly to look like this:
I maybe ought to have moved them a little closer in than this, even.
Speaking of the animal’s hands, that reminds me. How exactly does this happen?
You know, most animals don’t really understand about electricity; once they learn that they can’t touch a thing or they get a painful zap, they just leave it alone. Is there any explanation for how the tyrannosaur is magically able to know that the power is out and that it should immediately grab the nearest fence? And how is it possible that a Tyrannosaurus could touch something with its tiny little arm in such a way that you could see the arm and not the not the rest of the animal? What’s happening in that shot?
And while we’re on the subject of things that don’t make sense…
Okay, so Tyrannosaurus is heavy, but it’s not that heavy. Think “two big elephants” sort of heavy. Have you ever been to the elephant house at the zoo? It turns out the ground doesn’t vibrate, or anything close to it. Dinosaurs were lighter than you would probably think; there is a law of physics known as the cube-square law which basically states that as you increase the size of a thing, the volume of it will increase faster than the surface area, meaning that a three-dimensional object that works perfectly well on a smaller scale will quickly become unsustainable when enlarged. We’ve all seen those movies wherein some ordinary creature becomes subjected to nuclear whatever and becomes a fifty-foot monster version of itself; in the real world, these things would never work, because if you scale up an iguana or an ant or something without adding any special adaptions it will simply crush itself under its own weight of mass. Dinosaurs, on the other hand, were built to be huge and had adaptions for lighter skeletons and so on. To be fair, our methods of calculating their probable weights and therefore our estimates have evolved several times since the movie came out, so I can’t fully blame Spielberg and co. for this one, but still; the point is there.
I think that leaves me with only one more thing I wanted to cover today, and that’s the Jeep chase. It’s really hard to work out a long-extinct animal’s top speed in life, but none of today’s scientific guesses are kind to this scene – estimates range from about 25mph at the top end and 12mph at the bottom, which seems to be something that would pose no problem at all for somebody escaping in a car – but then, it’s important to remember that the chase occurs on a muddy, uneven jungle road directly after a tropical storm. It’s also probably worth pointing out that the T. rex in the film isn’t actually running per se but moving in a fast walk – Rexy always has at least one foot firmly on the ground throughout. This might even turn out to be palaeo-accurate behaviour, in fact, because there was a study by the University of Manchester earlier this year suggesting that T.rex‘s leg bones wouldn’t have been up to the impact stresses of full-on running.
Well, that about wraps it up for Tyrannosaurus rex! Thank you for reading. Join me again next time and I’ll be discussing what’s cool… or not… about the movie’s depiction of Dilophosaurus!