Skip to Content

Is A Dinosaur a Reptile, Mammal, Bird, or Something Else?

With dinosaurs not being around anymore, it’s harder to gather information about these prehistoric giants. For example, what are dinosaurs? Were they considered to be mammals like an elephant? Were they considered birds? Or were they considered to be reptiles?

Dinosaurs are considered to be reptiles, with characteristics such as being cold-blooded, being covered in dry, scaly skin, laying eggs, and more. Dinosaurs are most closely related to reptiles, as oppose to mammals or birds, because of these characteristics.

Let us look at the differences between a mammal, a bird, and a reptile, and how closely related the dinosaur was to each of these categories of animals; and how it was then decided that a dinosaur was a reptile.

What Is A Mammal?

A mammal is an animal that is distinguished by a few very specific characteristics. The characteristics that mammals are known by are as follows:

  • Mammals are warm-blooded animals – almost all mammals are warm-blooded; there are mammals that can live in extremely cold environments; however, no mammal will ever have their blood be “cold-blooded” like a snake or frog.
  • Mammals are vertebrates – mammals will have a spinal column or a backbone, which is also known as vertebrae.
  • Mammals have long hair or fur – mammals will generally be covered in fur or hair. There are some exceptions, though; for example, whales, hippopotamuses, and porpoises are furless and hairless mammals.
  • Mammals secrete milk to nourish their young with – female mammals will produce milk and feed their babies as oppose to their young eating solid food right away. Animals that are the exceptions to this rule include the platypus and the echidna.
  • Mammals (usually) give birth to live young – mammals give birth to their young live, as opposed to laying eggs. There are only a hand full of exceptions to this rule; for example, the platypus and the echidna are egg-laying mammals.

Mammals are animals that will have all of these characteristics (except for the one or two exceptions to the rules.)

Note: This post may contain affiliate links which will take you to online retailers that sell products and services. If you click on one and buy something, I may earn from qualifying purchases. See my Affiliate Disclosure for more details.

Therefore, if a dinosaur were to be a mammal, it would need to have ticked (almost) all of these boxes. Since most dinosaurs would not tick even half of these boxes, it is safe to say that dinosaurs were most likely not mammals.

What Is A Bird?

A bird is another type of animal, and even though they are vertebrates and are warm-blooded, they are not mammals.

The trait characteristics that help identify a bird as being a bird are as follows:

  • Birds are warm-blooded – all birds are warm-blooded; there are no cold-blooded birds and no exceptions to this rule.
  • Birds are egg-laying animals – all birds lay eggs; this means that birds do not give birth to live young. There is no exception to this; all birds lay eggs.
  • Birds possess feathers – all birds have feathers. There is no exception to this rule. Many birds have feathers that look different and are unique to their needs and environment, but all birds do have feathers.
  • Birds possess wings – all birds possess wings. There is no exception to this; even the birds who do not have the ability to fly still have wings.
  • Birds possess a beak – birds will always have a beak. There are no exceptions to this characteristic.
  • Birds (minus a few exceptions) have the ability to fly – most birds have the ability to fly and will do so on a daily basis. There are, however, some birds that do not have the ability to fly. These birds include the ostrich, the weka, the kakapo, the emu, the penguin, the kiwi, and the cassowary.

Because dinosaurs would have to tick 95% of these boxes to be considered a bird, it is a fair statement to say that dinosaurs were definitely not birds.

What Is A Reptile?

Dry, scaly skin is one of the characteristics of a reptile

The characteristics that define a reptile are slightly more complicated than those that define a bird or a mammal.

Reptiles come in a very wide range of shapes and sizes; legs and no legs; colors and camouflage.

However, the main characteristics that define a reptile are as follows:

  • Reptiles are cold-blooded – all reptiles are cold-blooded; some reptiles can raise their body temperatures to high levels, but they are always cold-blooded.
  • Reptiles have dry, scaly skin – all reptiles will have dry and scaly/scale-like skin.
  • Reptiles generally lay soft-shelled eggs on land – most reptiles lay eggs instead of giving birth to live young. The exception to this is the very few reptiles that are Ovoviviparity; this means that they have eggs, but they keep them inside of their bodies. Their babies will then hatch out of their eggs inside the mother, which means that technically the mother will then technically give birth to live young.
  • Reptiles fertilize their eggs internally – all reptiles fertilize their eggs internally.
  • Reptiles have at least one lung – all reptiles have a minimum of one lung and will breathe using their lung/lungs.
  • Reptiles are vertebrates – all reptiles are vertebrates; they all have a spinal cord or backbone of some form.

Because of these characteristics, it is clear to see that dinosaurs have the most in common with reptiles out of these three categories of animals.

Check out “How Do We Know Dinosaurs Had Scales?”

So What Is A Dinosaur? A Mammal, A Bird, Or A Reptile?

Dinosaurs are classified as being a reptile!

Dinosaurs were cold-blooded animals. It has been assumed that in many of the larger dinosaurs, their body temperatures may have been stabilized due to their large size, which may have made them “warm-blooded”; however, they were, in fact, cold-blooded animals.

Dinosaurs are known to have had very dry, scaly, or scale-like skin. Most dinosaurs are believed to have been very reptile-like in their appearance, with most of them being mostly covered from head to toe in scales.

Although they may or may not have been soft shells (there is no way of knowing for sure), dinosaurs did not give birth to live young; they would lay multiple eggs at a time.

It is still unclear if absolutely all dinosaurs laid eggs since there have only ever been a rare few dinosaurs that have been found still in their eggs; however, scientists’ best assumptions have lead to the conclusion that most dinosaurs did, in fact, lay eggs.

It has been assumed by scientists that dinosaurs would mate with their partners the same way back then that modern reptiles do now, and therefore, it has been assumed that like modern-day reptiles, all dinosaur eggs were fertilized internally.

After mating, female dinosaurs would develop the fertilized eggs inside of them, and then when they were ready, they would lay their eggs somewhere they deemed safe on the land, the same way that most modern-day reptiles do.

Obviously, there is no way that this can be proven, though, as there is no actual proof that this was the way that dinosaurs mated. Scientists have simply used their best resources and best understanding to try and figure out this information.

Dinosaurs had lungs! Yet another box that can be ticked off of the reptile checklist.

Dinosaurs would breathe using lungs; in some dinosaurs, their lungs are actually assumed to be relatively similar to a bird’s lungs.

This is not the case in all dinosaurs, though, and has been the subject of many debates amongst scientists and paleontologists for years.

There is no way to prove either side, whether all dinosaurs had these types of lungs or whether it was simply the dinosaurs that could fly and a selected few that roamed the land.

Without further proof on either side of the debate, there is no way of knowing what kind of lungs these reptiles had; but either way, it is known that they did have lungs!

Dinosaurs were vertebrates, which means they had a spinal chord or a backbone

This one is no surprise to anyone who has ever been to a museum or seen any dinosaur skeleton; dinosaurs were vertebrates.

Vertebrates are animals that have either a spinal cord or a backbone, and these giants definitely had very big backbones!

With all that has been seen about dinosaurs above, it is easy to understand how they have been happily classified as being reptiles.

Are There Still Any Dinosaurs Around Today?

You would be surprised by how many people ask this question; you also may be surprised at the answer.

Although they may not be considered dinosaurs, many animals from the prehistoric area that were around when the dinosaurs were around are still around now in our day and age.

There are actually many animals that were alive with the dinosaurs and have made it through all these years to still be around today; some of these animals include:

  • The gharial
  • the komodo dragon
  • the echidna
  • the chambered nautilus
  • the tapir
  • the wobbegong shark

Let’s take a look at each one and how long they have actually been around!

The Gharial

This type of crocodile has been around for tens of millions of years, and its appearance truly does fit the “prehistoric” look!

These amazing creatures have managed to survive for all of these years, and even though they are now facing extinction, there is a breeding center in Lucknow, India, called the Kukrail Forest Reserve, that is helping with the conservation of the Gharial.

The Komodo Dragon

Another prehistoric animal that definitely looks the part, the Komodo Dragon, looks slightly like a dinosaur.

These massive lizards date back millions of years ago and can still be found today in countries such as Indonesia.

Komodo Dragons are massive reptiles, with most of them weighing as much as (and some of them weighing more than) an adult human.

As amazing as these animals are, they should always only be viewed from a distance since they have been known to attack people, and a bite from one of these guys will not only hurt but could also have some serious consequences since they possess venom glands.

The Echidna

Remember this animal that was listed in the “mammal” section above? Well, as it turns out, these little creatures that look like a mix between an anteater and a porcupine are prehistoric.

The echidna has been around for roughly seventeen million years! It is absolutely amazing that these tiny animals have managed to come so far and last in the wild throughout so many years.

Even though these animals may not look tough (in fact, they look pretty cute!) but they have made it through millions of years and are still strong and thriving today.

Chambered Nautilus

Although this tiny sea creature may not seem impressive, it really, really is.

The Chambered Nautilus was not only around when the dinosaurs still roamed the earth, but from what scientists can tell, it was around long before them.

That means that this little creature was around long before the dinosaurs and is still around now today, long after dinosaurs.

These animals have been around for roughly five-hundred million years – how amazing is that? These prehistoric sea creatures are making sure that they are making a name for themselves as some of the oldest animals still around today.


Tapirs existed during the time of the dinosaurs and are still around today

The Tapir is kind of the prehistoric pig, except for one crazy feature – their nose!

The Tapir has a nose that almost reassembles a short elephant trunk that they use to get food into their mouths.

Tapirs were often featured in the ice age movies as they were some of the most common animals around in that time period.

It has been established that the Tapir has been around for around twenty-three million years – and they are still around today in countries like Asia and certain parts of America too.

Wobbegong Shark

The wobbegong shark is a truly prehistoric-looking animal – from head to “toe”, this creature looks like it just stepped out of a Jurassic Park movie!

Wobbegong sharks have been estimated to have been around for around eleven million years, and thankfully they are still thriving in the ocean.

Although these animals may look tough and mean, these sharks hardly ever attack people, and in the rare cases that have been reported, it is usually due to accidentally standing on them since they will generally try and hide from humans and do it a little too well.


There are very big differences between mammals, birds, and reptiles; each category of animal having very specific features to qualify the animals in that category.

Even though with the massive sizes of some of these giant dinosaurs, you would assume that they would be closely related to animals such as the elephant, hippopotamus, or the rhino, which are all mammals, they are, in fact, reptiles.

Dinosaurs might have roamed the earth for many years as the biggest creatures alive, but sadly today, they are all gone, and scientists have had to use their best-educated guesses and understandings to try and gain knowledge on what these animals were like.

There are still facts about dinosaurs that are argued about amongst scientists, such as their lungs and their mating habits, but overall one thing has been agreed upon; dinosaurs were reptiles.

Dinosaurs tick every box as far as the characteristics of a reptile go, and therefore are safely categorized as being reptiles.

As sad as it is that dinosaurs are no longer around in this day and age, there are many different prehistoric animals that are.

Most of the animals that were around back then that are still around today are sadly now also close to extinction, and a large part of that is due to humans.

We may no longer have dinosaurs around today but let us try and do everything that we can to help keep their friends around for many years to come!

You Might Also Like: