MYTH: Pterodactyls are dinosaurs

27 November 2018

Interview with

Georgia Mills

It’s mythconception time, and Georgia Mills has been ruffling her feathers about this claim…

Georgia - If you’re anything like me, a disproportionate amount of time is spent discussing which dinosaurs were the coolest. Was it the mighty tyrannosaur? The armoured ankylosaurus? Or the fabulously feathered archaeopteryx? Although, on occasion, someone might unwittingly chip in that their favourite dinosaur was a pterodactyl. To which, for the paleontological pedant, there is only one response.

No. Pterodactyls are not your favourite dinosaur, because pterodactyls are not dinosaurs. The offender then gets an unexpected and unwanted lecture in reptile evolution.

The story explaining just why they are wrong starts just over 300 million years ago when the ancestors of all modern reptiles and birds first appeared. Just like the Beatles, they couldn’t stay in one group forever, and broke up, or speciated. Like branches on a tree, different styles of reptile start appearing, changing, and then splitting up again - all over millions of years. 

One of the branches that broke off contain the ancestors of all modern lizards and snakes. While another got busy becoming crocodiles – who have remained virtually unchanged since before the start of the Jurassic. Evolution obviously adheres to the old adage - if it ain’t broke, don’t fix it.

Then, still before the dinosaurs begin, another branch of reptiles diverges. And this group did something a little unusual: their front limbs turned, over time, into wings and they took to the skies. They became the group known as the pterosaurs. The ancestors of all pterosaurs split off from this evolutionary tree before the dinosaurs came to be, so while they ruled the skies at the same time as dinosaurs ruled the land, they shouldn’t be called dinosaurs anymore than bats should be called cows.

Another group that are frequently mistaken for dinosaurs are the ichthyosaurs and plesiosaurs. These amazing reptiles found their way back into the oceans and while they were terrifying marine predators, dinosaurs they were not.

So how do we know? The clue to how the family tree is laid out lies in the fossil record and for dinosaurs there are a few characteristics in their skeletons that every single member will have – from the long necked diplodocuses to the tiny feathered velociraptor.

These features include backwards facing shoulder blade, a hole in the hip socket and holding limbs directly under the body. Pterosaurs and marine reptiles just don’t have that many of the same characteristics, so we know that they’re not from the same group. 

If the pterodactyl-loving offender can cope with any more correcting, you might also want to let them know there’s technically no such thing as a pterodactyl anyway, it’s an outdated term and they’re now known as pterosaurs.

So that’s why pterodactyls don’t qualify as dinosaurs or indeed anything. And it's also the reason paleontologists don't get invited to many parties.

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