What’s the difference between a pterosaur and a dinosaur?
…were you expecting a punchline?
Referring to a pterosaur as a dinosaur is a capital offence for paleontologists and those studying the field. After noticing a New York Post article referring to Pterosaurs as dinosaurs, I felt the need to write this post in response:
Now, I know it doesn’t seem like too big of a deal. After all, both are extinct reptiles that lived alongside each other during the Mesozoic era. So why are paleontologists so sensitive about it? Why are pterosaurs and dinosaurs considered distinct? And what’s so important about establishing the difference between the two?
To answer, we must first get to know the two lineages. The pterosaurs were flying reptiles that evolved sometime during the early Triassic period, about 250 million years ago. They were an immensely diverse group, with some members being the size of bats, while others were 13-meter giants the height of Giraffes. Pterosaurs were the first family to develop powered flight and one of only three vertebrate groups to do so, alongside bats and birds. Their extinction coincided with the non-avian dinosaurs 65 million years ago, unfortunately ending their lineage for good.
I think most people know about dinosaurs, but it’s still good to refresh. Dinosaurs evolved around the same time as the pterosaurs but survived the end-cretaceous extinction in the form of birds. From there, they evolved into three separate clades: the Sauropods, or long-necked dinosaurs; the theropods, a mainly carnivorous clade; and the Ornithischians, or “bird-hipped” dinosaurs.
Both dinosaurs and pterosaurs are part of the Archosauria family, a clade of reptiles that includes crocodiles. Dinosaurs and pterosaurs were close relatives within Archosauria; other than birds, pterosaurs were the closest ancestors to dinosaurs. Though the two lineages are close to each other from an evolutionary perspective and do share some biological features, this does not mean the two are synonymous with each other.
At first glance, their physical differences are seemingly minute. While dinosaurs have a hole in their hip socket and a crest in their arm bones, pterosaurs have neither feature. Despite how insignificant these differences may seem, they still contribute to how paleontologists distinguish the two lineages.
The more important reason for their difference is due to a lack of common ancestry. To be part of a family, all members of that family must share a common ancestor, or a single species that the family descended from. Since birds and dinosaurs like Tyrannosaurus and Stegosaurus all have the same unknown common ancestor, they are all within the dinosaur family. Since pterosaurs diverged from the dinosaurs before the evolution of this common ancestor, they cannot be classified as dinosaurs. It’s for this exact reason that a seal isn’t considered to be a whale; since they diverged far before the common ancestor of whales, they aren’t part of the family.
Shame they’ll miss the reunion.
So, pterosaurs aren’t dinosaurs because of…phylogeny. I know it’s not the most exciting way to differentiate the two, but it certainly makes it easy for paleontologists. By differentiating the two, paleontologists can focus on what made each family unique and how each lineage evolved over time.
It should be common knowledge that dinosaurs and pterosaurs are different. Yet, the idea that pterosaurs – and other extinct animals, for that matter – are the same as dinosaurs remains prevalent in popular culture. This can largely be attributed to media bias towards the views generated by dinosaurs. Even reputable sources like the BBC have fallen victim to occasionally gaslighting pterosaurs as dinosaurs for clicks and attention.
But would saying “flying reptiles” instead make it any less appealing? For example, if I told you that a flying reptile with a 13-meter wingspan potentially ate dinosaurs, would that make it any less awesome?
If anything, it makes it better!
I do not take credit for any image found in this article.
Header image courtesy of Julius Csotonyi and Alexandra Lefort, found here
Pterosaur nest courtesy of Gabriel Ugueto, found here
Pterosaur and Dinosaur lineage found here
Pterosaurs in flight courtesy of Julio Lacerda, found here
Barta, Danny. “Why Isn’t a Pterodactyl a Dinosaur? YouTube, uploaded by The American Museum of Natural History, April 14, 2018. https://www.youtube.com/watch?v=muWYY9qMM1A
Black, Riley. “Why a Pterosaur Is Not a Dinosaur.” Smithsonian.com, Smithsonian Institution, 18 Nov. 2010, https://www.smithsonianmag.com/science-nature/why-a-pterosaur-is-not-a-dinosaur-87082921/.
Pollard, Chris. “Dinosaurs Swallowed Prey Whole and Spat out Their Bones.” New York Post, New York Post, 8 Feb. 2022, https://nypost.com/2022/02/08/dinosaurs-swallowed-prey-whole-and-spat-out-their-bones/.