12 Famous Prehistoric Animals You'll Be Surprised To Learn Aren't Actually Dinosaurs

Dinosaurs are probably the most popular dead things on planet Earth, but there are a lot of misconceptions about these immortal legendary lizards. Pop culture still hasn't come to terms with the reality that many dinosaurs were, in fact, covered in feathers and that many of the animals they consider "dinosaurs" actually weren't. The average person doesn't seem to truly know what a dinosaur is. 

For the general public, the word "dinosaur" is often used as a catch-all term to describe any sort of reptilian creature no longer living and hailing from the vaguely distant past. This is unfortunate, because dinosaurs are actually a very specific group of animals that share the same evolved traits. They laid eggs, were warm-blooded, and lived on land. That last part is important, and is one of the quickest ways to know if you're dealing with a dinosaur or something else.

Flying dinosaurs? Nope, not a thing. Aquatic dinosaurs? Again, not actual dinosaurs. There are lots of ancient animals mistaken for dinosaurs, some of which aren't even reptiles. Here is a selection of some of the most popular prehistoric animals that aren't dinosaurs that are commonly confused for their terrifying cousins.


  • Even though pterodactyls filled the skies above the dinosaurs, they were not part of the same family. Pterodactyls are actually pterosaurs, an extinct group of reptiles that evolved to take flight.

    They had very different body structures than modern birds - birds being actual descendants of dinosaurs and therefore more dinosaur than a pterodactyl could ever hope to be. Unlike birds, pterosaurs had weak hind-legs that played a minimal role during take-off. Instead of building up speed by running, pterosaurs used their powerful wings to launch themselves into the sky.

  • Dimetrodon
    Photo: Charles R. Knight / Wikimedia Commons / Public Domain

    Contrary to popular belief, the sail-backed dimetrodon is not a dinosaur. It's actually a synapsid, a group of animals that is much older than the dinosaurs and a precursor to modern mammals. If you look far back enough in your family tree, eventually your relatives will start looking a lot like dimetrodon.

    Dimetrodon thrived during the Permian era, 35 million years before the first dinosaurs had even evolved. There were many different species, but the largest and most famous was a 10-foot long monster. They had serrated teeth perfect for carving flesh, making them one of the Permian's most successful predators.

  • Although these aquatic reptiles are featured in the movie Jurassic World, they didn't live during the Jurassic period and aren't true dinosaurs. Mosasaurs are thought to have evolved in the early Cretaceous period, the last epoch before the extinction event that wiped out most large life forms.

    These giant sea-lizards were ferocious predators known for their powerful bite, but they were also highly evolved and sophisticated organisms. Mosasaurs are believed to have been warm-blooded, much like their dinosaur cousins, and there is evidence that they gave birth to live young.

  • Quetzalcoatlus
    Photo: Mark Witton and Darren Naish / Wikimedia Commons / CC-BY 3.0

    Quetzalcoatlus was an absolute behemoth. It dominated the skies and is the largest animal ever to take flight. This impressive pterosaur was named after the feathered serpent god Quetzalcoatl, a Mayan deity believed to rule over the earth and sea.

    This giant reptile lived right at the tail end of the Cretaceous era, about 68 million years ago. They had a massive 36-foot wingspan, and estimates put their weight at nearly 600 pounds. To put that in perspective, the heaviest bird alive today (the Andean condor) only weighs about 33 pounds. They were too big to flap their wings much, choosing instead to soar high and let nature and physics do the heavy lifting. Like modern birds, pterosaurs were believed to have hollow bones which helped keep them light.