Are Birds Dinosaurs?

If you’ve ever seen a rendition of what dinosaurs may have looked like millions of years ago, then you know they look terrifying and cool but also somewhat familiar. The ancestors of dinosaurs are still alive and well today, living their best modern lives. So are birds dinosaurs? And if so, how closely related are they? Let’s find out!

Is a Bird Considered a Dinosaur?

Yes. Birds are avian dinosaurs and technically reptiles. Here’s an excellent article breaking down why birds are reptiles.

Birds have evolved over 150 million years from therapod dinosaurs into our modern-day flying friends that inhabit parks, backyards, forests, and most other habitats on earth. Therapods were two-legged dinosaurs, such as the Tyrannosaurus rex and velociraptors. These creatures were likely the first to possess feathers.

Some feathered therapod dinosaurs survived after the mass extinction, and this small group is where modern birds likely evolved from. 

Dinosaurs essentially shrank and became what they are today. They developed a smaller, lightweight bone structure, their tails shrank, and they grew flight feathers, eventually making them aerodynamic. Groups split apart and developed their unique features, now comprising the tens of thousands of bird species that exist now.

Why Are Birds Not Classified as Dinosaurs?

If birds are technically dinosaurs, why are they not classified as such? Semantics is the issue.

While birds are technically reptiles, “reptile” isn’t a valid classification category. Not to mention, our modern birds don’t have reptile characteristics. Paraphyletic groups, like “reptile” and “bony fish” consist of a common ancestor. But birds have had such major transformations that drastically differentiate them from other members of these clades.

Do All Birds Evolve from Dinosaurs?

Yes, all birds evolved from avian dinosaurs. Birds were the only dinosaurs to survive the mass extinction event millions of years ago. And they evolved over a long period to become what they are today.

What is the Closest Bird to a Dinosaur?

There are several species today that are confirmed as being closely similar to dinosaurs.

Cassowaries are large-bodied birds with big feet and sharp claws. And they also have hard, helmet-like structures on their heads similar to what dinosaurs would have had. The helmet protects its head as it runs through dense forests. Its deep booming calls are possibly close to what its ancestors sounded like.

Chickens and ostriches are also directly linked to the giant T. rex and are considered its closest-living relative. They have anatomical similarities, but researchers also discovered that their collagen molecules were closely related. It’s hard to believe that such a common, average creature could be a direct descendent of this mighty dinosaur.

Dodo Birds

The dodo was a flightless bird endemic to an island east of Madagascar. This bird went extinct in 1681 from introduced animals and hunting. Because dodos were birds, they were technically descendants of dinosaurs, like all birds. One of the closest living relatives of dodo birds today is Southeast Asian Nicobar pigeons.

Shoebill Birds

By now, you know that all bird species are related to dinosaurs. But some species look like they are closer to their ancient ancestors than others. One look at the shoebill stork and will think it belongs in a Jurassic Park movie. But, technically, these birds are no closer related to dinosaurs than other birds. These large, unusual-looking birds are endemic to the swamps of Central and East Africa.

Cassowary Birds

As mentioned above, cassowaries are also related to dinosaurs. And their unique characteristics, such as their helmet structure and booming voice, prove that birds are definitely related to dinosaurs.

Birds and Dinosaurs Similarities

Birds have scales similar to reptiles. While most of their bodies are covered in feathers, their feet feature scales that provide protection and prevent water loss. They are also vertebrate animals that lay amniotic eggs with shells. And they share behaviors similar to dinosaurs, such as brooding and nesting. These characteristics first arose in some dinosaur species. Some dinosaurs were also feathered, had hollow bones, had wishbones, and slept in similar positions as birds.

The photo featured at the top of this post is © Kensho Photographic/Shutterstock.com