Hey, smart people, Joe here.

So my friend Emily Graslie from "The Brain Scoop" came to visit a while back, and we did what you do when you're hanging out with Emily, which is go look at some bones from some awesome prehistoric creatures.

That big thing above our heads, that's a giant pterosaur named Quetzalcoatlus.

Now, seeing his bones up close kind of blew my mind.

I mean, this was a giant winged reptile that stood as tall as a giraffe, probably weighed as much as a grizzly bear, which would make it the largest and heaviest animal that's ever flown.

To put that into perspective, this is a wandering albatross, the largest flying animal alive today.

And this is Argentavis, an extinct bird of prey and the largest flying bird that ever lived.

And that is Quetzalcoatlus.

It's 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 a creature that huge 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.

[bird trills] Now it turns out scientists have been trying to solve this mystery of whether giant pterosaurs could fly for decades, and that they might have finally done it by thinking not just like paleontologists, but also by looking to aerospace engineering and mathematics.

[music playing] Dr. Michael Habib is one of those scientists.

So I called him up to get some answers.

I am a paleontologist.

We're called biomechanists, which is to say that I study the motion and physics of living and fossil animals.

Can you just give us an idea, what is a pterosaur?

Pterosaurs represent an extinct group of flying reptiles.

They can be found in small toys marked "dinosaurs," which is terribly misleading because they were not, in fact, dinosaurs.

There are such a thing as flying dinosaurs.

We call them birds.

And there are about 12,000 living species of them.

But the last pterosaurs perished at the end of the Cretaceous, along with the last of the non-bird dinosaurs.

(Joe Hanson) These guys were, by far, the earliest flying vertebrates.

I mean, the earliest pterosaur fossils go back to about 230 million years ago, and they owned the skies for almost 160 million years.

Birds have only existed for about 150 million years, so that's pretty impressive.

But pterosaurs are not dinosaurs.

I just want to emphasize that again.

Not dinosaurs.

They're their own thing.

The Dinobots have some explaining to do.

[music playing] Where were we?

Where the average pterosaur was around, say, one to two meters wingspans, the smallest one could fit in the palm of your hand.

Sounds cute.

And--which is very cute.

And when I'm talking about the largest pterosaurs, I'm talking about a three-way tie between Quetzalcoatlus, which was the first giant discovered.

More recently, discovered one called Hatzegopteryx of Transylvania.

And then just recently named is Cryodrakon, the frozen dragon, which is from Alberta, Canada.

OK, Cryodrakon is hands down 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 alive on earth today, it is pretty hard to imagine one of these giants actually flying.

So how could they have done it?

Well, it turns out to fly, you really need to master two things-- being able to generate lift to stay in the air and also getting into the air in the first place.

Now, staying in the air is actually not the hardest part for a giant flying creature.

The wings of birds and bats and pterosaurs are shaped like airfoils.

They're thick at one end, where the bones of the limb are and thinner at the trailing end, where it's either feathers or the wing membrane.

The flapping draws this airfoil through the air, creating both lift and thrust.

And it turns out, a big animal with big flapping muscles like Quetzalcoatlus would have had more than enough power to create sufficient lift and thrust to fly.

Hmm, hmm, hmm.

You know, to show you what I mean, I think we should take a closer look at some bones.

Some old bones.

Luckily, Quetzalcoatlus was discovered in my home state of Texas, and those bones happen to be just down the road at the University of Texas Vertebrate Paleontology Library.

So these are the actual bones of Quetzalcoatlus.

This really heavy drawer is full of some of the wing bones from this giant flying pterosaur.

There are a lot of adaptations throughout the skeleton of a pterosaur that allow it to fly.

And one of the things that really jumps out at people when they look at this big humerus, so there's this big prong that sticks up here out of the bone that is the source for all of the muscles to attach and stretch across to the chest, where they attach to the breastbone, basically.

So the bones tell us that these things had massive arm and chest muscles in order to provide enough force to cut that giant airfoil wing through the air.

But that's not the only flight adaptation that we can see in pterosaur bones.

I know one of the things that birds' adaptation is they have partially hollow bones?

That's right, yeah.

And so pterosaurs do the same thing.

So we can take a look at the smaller species to compare the cross section of a broken bone.

Let's do it.

[grunts] [whispering] I'm working out.

So this is the ulna from the small animal.

So if we look at this in cross section, you can see that there's a thin rim of dark gray bone around the outside of this.

It's about, oh, two millimeters or so wide.

(Joe Hanson) All that lighter part in the middle would have been hollow when this pterosaur was alive, just like bird bones.

But that bone is not much thicker than a large egg shell, and it had to support the weight of all of those muscles and a grizzly bear-sized body in flight without snapping in half.

I mean, how did it do that?

So if you're a pterosaur, you have probably the weirdest hands that have ever evolved.

They only had four fingers.

They did not have a fifth finger,