How Did Giant Pterosaurs Fly?

Hello smart people, Joe here. So my friend Emily Graslie from The Brain Scoop came to visit a while ago and we did what you do when you're with Emily, which is go look at some bones of some amazing prehistoric creatures. That big thing over our heads? It is a

giant

pterosaur called Quetzalcoatlus. Seeing that up close blew my mind. I mean this was a

giant

winged reptile that was as tall as a giraffe and probably weighed as much as a grizzly bear, which would make it the largest and heaviest animal that ever flew. To put this in perspective, this is a wandering albatross, the largest flying animal that exists today.

And this is Argentavis, an extinct bird of prey and the largest flying bird that has ever existed. And that is Quetzalcoatlus. It is closer in size to an F-16 than a bird. Now, I don't know about you, but it's pretty hard for me to imagine such a large creature taking to the skies. I mean, you can't argue with the laws of physics, and just because something has wings doesn't mean it can fly. It turns out that scientists have been trying to solve the mystery of whether giant

pterosaurs

could fly for decades. And they may have finally achieved it, thinking not only like paleontologists, but also looking towards aerospace engineering and mathematics.

Michael Habib is one of those scientists, so I called him to get some answers. I am a paleontologist, what we call biomechanist, that is, I study the movement and physics of living and fossil animals. Can you give us an idea of ​​what a pterosaur is? So,

pterosaurs

represent an extinct group of flying reptiles. They can be found on small toys marked "dinosaurs," which is terribly misleading because they weren't actually dinosaurs. There are flying dinosaurs, we call them birds and there are 12,000 living species of them. But the last pterosaurs perished at the end of the Cretaceous with the last of the non-avian dinosaurs.

These guys were by far the first flying vertebrates. The first pterosaur fossils date back to about 230 million years ago and ruled the skies for almost 160 million years. Birds have only been around for about 150 million years, which is pretty impressive. But pterosaurs are not dinosaurs. I just want to emphasize that again. Not dinosaurs. They are your thing. The Dinobots have some explaining to do. Where were we? The average pterosaur had about a meter or two in wingspan. The smallest one could fit in the palm of your hand. Sounds cute! Which is very nice. And when you talk about the largest pterosaurs, I'm talking about a three-way link between Quetzalcoatlus, which is the first giant discovered.

More recently, one called Hatzegopteryx was rediscovered from Transylvania, and was recently named Cryodrakon “The Frozen Dragon” from Alberta, Canada. Ok, Cryodrakon is easily the coolest name ever given to any extinct reptile. I mean “frozen dragon”! Eat your heart out George R. R. Martin. Based on what we see on Earth today, it is quite difficult to imagine one of these giants flying. So how could they have done it? Well, it turns out that to fly you really need to master two things: being able to generate lift to stay in the air, and also getting airborne in the first place.

Now, staying in the air isn't the hardest part for a giant flying creature. The wings of birds, bats, and pterosaurs are shaped like airfoils, thick at one end, where the limb bones are, and thinner at the rear end, where the feathers or wing membrane are located. The flapping pulls this profile through the air, creating both lift and thrust. It turns out that a large animal with large flapping muscles, like Quetzalcoatlus, would have more than enough power to create enough lift and thrust to fly. You know, to show you what I mean, I think we should take a closer look at some bones.

Some old bones. Fortunately, Quetzalcoatlus was discovered in my home state of Texas and those bones are located just down the street at the University of Texas Vertebrate Paleontology Library. Yes, these are the real bones of Quetzalcoatlus. Wow, and this really heavy drawer is filled with some of the wing bones of this giant flying pterosaur. So there are many adaptations throughout the pterosaur skeleton that allowed it to fly. And one of the things that jumped out when people looked at this humerus is that there's a big point sticking out here, outside of the bone, which is the source for all the muscles to come together and stretch across the chest, where they join the sternum. basically.

So the bones tell us that these things had huge muscles in their arms and chest to provide enough force to slice that giant wing through the air. But that's not the only flight adaptation we can see in pterosaur bones. I know one of the things that birds did, an adaptation, they have partially hollow bones? Yes, that's right, and pterosaurs did the same thing. Then we can take a look at the smaller species to compare the cross section of the broken bones. Ugghhh (I exercise) So this is the small animal's ulna. So if we look at this in cross section we can see that there is a thin edge of dark gray bone about 2mm wide.

That whole lighter part in the middle would have been hollow when this pterosaur was alive, just like the bird bones. But that bone isn't much thicker than a large eggshell. And it had to support the weight of all those muscles and a body the size of a grizzly bear in flight, without breaking in half. How did that? So if you're a pterosaur, you have the strangest hands that have ever evolved. They only had four fingers, they did not have a fifth finger, so their little finger would be absent. And the thumb, middle and index finger would be basically normal for a reptile.

And then the ring finger, the ring finger, would be huge. It would be as thick as your wrist and as long as your entire leg. It's... that's hard to even imagine. I'm sitting here looking at my own hand thinking, okay, the first part makes sense. But you lost me with your ring finger. Imagine how much the rings would cost! J: I know! The weight bearing of this animal essentially hangs from this finger. Which is crazy. All of its wing bones, including the ring finger, are hollow. But it has that large diameter that makes it surprisingly strong.

Well, that's how giant pterosaurs adapted to staying airborne, but remember, there's a second thing an animal must master in order to fly: actually getting airborne. They need to give themselves enough speed boost so that the combination of ground speed from takeoff and wing flapping speed generates enough lift. And that turns out to be the hard part for giant fliers. Now, when I was a kid, the first time I saw a pterosaur was in the Disney movie Fantasia. So I grew up thinking that pterosaurs lived on cliffs and basically jumped off the edge to start flying. Well... my childhood is a lie.

It doesn't really help to fall off a cliff to reach that speed. At that point you're accelerating one gravity down and you really want to accelerate a couple of gravities up. And the way an animal, let's say on the ground, climbs up and moves forward quickly, is by jumping. I have a confession: I have spent my entire life thinking that birds launched themselves into the air just by flapping their wings and rising into the air. But if you watch a bird in slow motion, it turns out that they start with their wings raised and jump into flight.

H: Everything happens so fast by our standards that it seems like they are taking off, but they are not. They launch with their legs, so about 80-90% of the power for take-off in most birds comes from the legs. It turns out that most flying animals are good jumpers, and that's no coincidence. It's because they need that to take off. But pterosaurs are not birds. In fact, when it comes to taking off, they have an advantage that birds do not have. And it all goes back to those really strange wings. We know that they walked with their wings folded.

And they were probably good jumpers for their size. A giraffe can't jump very high, it is actually quite heavy and has a large torso. A pterosaur may be that tall, but it's a fraction of the weight. And he would have more muscles in his limbs. These things should be able to jump a couple of meters. That's more than they need to get the clearance and speed they need to start flapping. Unfortunately, we don't know exactly what it would have been like to see a large giraffe/bear/dragon leap several meters into the sky, but we can get an idea thanks to another flying animal.

Bats that take off from the ground walk on their wings and feet. They then walk quadrupedally, on all four limbs. Which means all four are available to jump. So when they jump, they get some power from the hind limbs and most of the power from the forelimbs, because the wings are bigger than the legs, it's a flying animal. And they can REALLY take off like a rocket. Birds: They are also tetrapods, they have four limbs, but they basically said "two of you will only be used for this special thing." And it seems like the pterosaurs were saying, "Let's combine our arms, let's get two good things out of this." “Let’s start jumping and flying.” Yes, they are taking the combined approach.

It ends up giving you a lot more room to grow. Because the birds end up stuck. You have a specialized motor for swimming, running, jumping and taking off. And the other one is fine, once we get up, you will take over and flap and keep us awake. And this is the key thing that has prevented birds from reaching the size of a giraffe. If you make your flutter muscles bigger, you'll have to push up with your throwing muscles, so they have to be bigger. But if you enlarge your throwing muscles, you will have more payload that you will have to carry in the air with your flutter muscles.

At some point, you're either too heavy to throw or too heavy to stay in the air. But if you use the same motor for your flutter and your takeoff, then you can get much heavier before physics keeps you on the ground. That also explains, quite well, why the largest pterosaurs have huge but surprisingly small forelimbs. One of my favorites, called Anhanguera, from Brazil, this animal has a wingspan of 4 to 5 meters, a head that is over a meter long, the neck is not far from that. The body: He has a big chest, but the rest of the body is like an afterthought, it's a small thing.

And the hind limbs are so small that the feet fit into an eye socket. Wow! I mean, I don't want to make fun of pterosaurs, but they have really ridiculous body proportions. So much head and neck, and the further you go back, you're right, it's like someone ran out of energy and said, I'll finish this later. Yeah, my joke is always that they skip leg day. They definitely skipped leg day. This is how we believe the largest flying animal ever took to the skies. What I love about this is that scientists wouldn't have solved this mystery if they hadn't combined different types of science.

Not only paleontology, but also aerospace engineering, mechanics and computer modeling. So before we had to sit with fossils or casts of fossils because the bones are too delicate to try to figure out how these animals moved, and what we've done a lot of lately is CT scanning. scanning or laser scanning of the surface of the bones, and we can study them quantitatively, making computer models so that we can test how these animals might have moved during their life. You build that pterosaur inside the computer, you put it in a wind tunnel, you throw it off a cliff, you put it in an attack dive, all kinds of interesting things.

We've had people who work on designing gliders and other airplanes come and look because when they're trying to find efficiencies and make faster, more fuel-efficient airplanes, looking at the fossil record is something we can apply. We've only been working on flight for a century and a half... Yes, we haven't been working on it for long! And they had tens of millions of years of practice. But as incredibly adapted as pterosaurs were to flight, they were no match for a rock the size of a small city falling from the sky and setting the atmosphere on fire. So unlike birds, all we know about pterosaurs is from their bones.

And honestly, after seeing those bones up close, I can't decide if it would be really cool or completely terrifying to have pterosaurs today. I think it would depend on which ones. I think I'd be perfectly happy seeing a small pterosaur that fits in the palm of my hand perched on my porch, but Quetzalcoatlus is hanging around, we can't go out today because it might eat the kids... that would be... It's like Game of Thrones . Dragons were cute when they were babies, but later they became troublesome children. II'm a little glad we have chickens. Stay curious.