Why aren't pterodactyls dinosaurs?

No matter how much you love pterodactyls, you need to think twice before telling someone they are your favorite dinosaur.

As early as 1834, the scientific community considered pterodactyl to be an obsolete informal name for a member of the order Pterosaurs, which includes all flying reptiles that lived during the Mesozoic Era (252.2 million to 66 million years ago). Pterosaurs were the first reptiles capable of flight and the first vertebrates to successfully fly, a feat they accomplished by using their strong front legs to launch their bodies into the air. Their wings are formed from a membrane of skin and are connected to the hand by a slender ring finger, not unlike a bat's fleshy wings.

But while pterosaurs lived among dinosaurs—and certainly looked a lot like dinosaurs to the untrained eye—the two groups were not the same. (Don't be fooled, though: It wasn't the wings that made them special. Dinosaurs also had some airborne descendants.)

Like humans and apes, pterosaurs and dinosaurs share a common ancestor, which explains the similarities between these creatures. (Again, you can't more accurately call a pterosaur a dinosaur, just like you can't call a human an ape.) Both pterosaurs and dinosaurs are part of the Avemetatarsalia clade of the subclass Archosauria, which includes alligators and crocodiles of close relatives. Close relatives of dinosaurs and pterosaurs. In Avemetatarsalia, however, there is a clear dividing line: dinosaurs and their relatives belong to one side of the order Dinosauriformes, and pterosaurs to the other. Although modern birds claim dinosaurs as their ancestors, none of the pterosaur descendants have avoided extinction.

If you can't find a reptile fossil to tell you its family, pterosaurs and dinosaurs can be distinguished by their bones. Skeletally, the two groups diverged about 250 million years ago, resulting in a number of physical differences, most notably in their appendages: dinosaurs had a cavity in their hip sockets and upper arm bones with A long crest, whereas pterosaurs had neither.

Unfortunately, all of this means that you shouldn't call pterosaurs your favorite dinosaur. Your favorite ancient flying reptile? certainly! When it comes to ancient reptiles, there's always more to learn and more misconceptions to correct. For example: Did dinosaurs really have feathers?

animal tags： pterodactyl dinosaur