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Are Chickens Dinosaurs?

Could it truly be that the chickens clucking away in your backyard are related to dinosaurs or could be dinosaurs themselves? Surprisingly, chickens, along with other modern day birds, have descended from dinosaurs. Evolution is intricate and spans millennia, as seen with theropod dinosaurs evolving into chickens. Let’s take a look at the connection between the wondrous dinosaurs of the past and our feathered friends of today.

A Bit of Dino In Your Chicken

Tyrannosaurus Rex skeleton
Tyrannosaurus Rex skeleton

The notion of chickens and Tyrannosaurus Rex sharing a common lineage might initially sound absurd, but modern science has unearthed compelling evidence to support this astonishing connection. To comprehend this link, we must journey back in time to explore the complex world of evolution and genetics.

Imagine, if you would, the legendary Tyrannosaurus Rex, affectionately referred to as T. Rex. This colossal predator ruled the Cretaceous period and continues to be one of the most fearsome creatures to have ever roamed the world. With its massive jaws, sharp teeth, and imposing presence, T. Rex strikes a vivid image of prehistoric might.

When Catastrophe Struck

Around 66 million years ago, a catastrophic event reshaped the planet’s biodiversity, leading to the mass extinction known as the Cretaceous-Paleogene event. This cataclysmic incident wiped out the majority of Earth’s species, including Tyrannosaurus Rex. However, it spared a select group of small theropods — birds. These survivors embarked on an evolutionary journey, ultimately evolving into the diverse avian species we encounter today.

In fact, research from Duke University found that most modern orders of birds that we see today, even the red junglefowl (Gallus gallus) that was used to breed the modern chicken, first formed around 10-15 million years ago after that extinction level event.

The Study Linking Dinosaurs to Chickens

Looking at a T. Rex and then at your chickens, you may be stumped to see any relation. However, the revelation that chickens and T. Rex are connected on the tree of life emerges from groundbreaking scientific research from 2008. This connection isn’t a mere coincidence but a result of meticulous molecular analysis. Scientists from the Beth Israel Deaconess Medical Center (BIDMC) and Harvard Medical School (HMS) have ventured into the realms of genetics, studying amino acid sequences in collagen from T. Rex fossils and comparing them with those of various modern species.

Astonishingly, the results indicated a closer genetic affinity between T. Rex and chickens than with any other living creature. This revelation might challenge our preconceptions but is firmly rooted in scientific data.

According to one of the researchers on the team, dinosaur proteins from a femur found in 2003 were used to extract soft tissue. Those tissues were then analyzed, finding that ostriches, chickens, green anole lizards, and even alligators all share a common ancestor: the mighty Tyrannosaurs Rex.

What Were The Theropods?

Theropod Dinosaurs

As mentioned earlier, the T. Rex was wiped out during the Cretaceous-Paleogene event, giving rise for another kind of carnivore to rule the lands that remained. The theropods were remarkable dinosaurs who were markedly different from their predecessors. They had hollow bones, a bipedal stance, and some even had feathers.

While feathers initially evolved for purposes other than flight, such as insulation and display, they laid the groundwork for the eventual emergence of powered flight. This evolutionary innovation is akin to the prelude of a grand symphony, setting the stage for the avian wonders to come.

Feathers are, in essence, modified scales — a fact that underscores the intricate interconnectedness of life’s building blocks. One of the most iconic examples of prehistoric birds is Archaeopteryx, a dinosaur that exhibited both feathered wings and reptilian traits.

Archaeopteryx dinosaur
Archaeopteryx dinosaur

How Are Chickens and Alligators Related?

Alligators and chickens share common ancestry with dinosaurs like Tyrannosaurus Rex and Velociraptors, but their evolutionary paths diverged dramatically. Alligators did not evolve from theropods but from archosaurs that retained their ancestral reptilian traits, including cold-bloodedness and a semiaquatic lifestyle. In contrast, theropods embarked on a trajectory marked by innovations such as warm-bloodedness, powered flight, and a transition from scales to feathers.

Interestingly, this is also why, despite their genetic similarities, chickens and turkeys are said to be the closest thing to the T. Rex and not the alligator.

How Did Dinosaurs Evolve Into Birds?

Dinosaurs used to be so large. Why did birds — their direct descendants — end up being so small? Where did birds even come from? You already know that birds and dinosaurs are linked genetically and that theropods had feathers. However, there seems to be a lot of time between theropods from millions of years ago to the birds of today. So, how exactly did it happen?

The truth is that it was a long process that occurred long before humans ever showed up. Here is a closer look at the evolutionary steps that transformed dinosaurs into chickens, turkeys, and other birds:

Over 200 Million Years Ago

It is believed that there is a common ancestor among all dinosaurs from the Cretaceous period and the dinosaurs that emerged from the Cretaceous-Paleogene event. This early archosaur laid the foundation for the subsequent divergence of the dinosaur lineage, which includes theropod dinosaurs, and other reptile groups.

160 Million Years Ago

Around 160 millions years ago, small theropod dinosaurs, similar to Compsognathus, started to evolve bird-like characteristics. These early theropods are bipedal, have lightweight skeletons, and possibly exhibit some feather-like structures.

150 Million Years Ago

the evolution of the feather

Feathered dinosaurs began to emerge. Fossil evidence shows the emergence of feathered dinosaurs, such as Sinosauropteryx and Caudipteryx. These dinosaurs possess true feathers, suggesting that feathers evolved as a feature well before the appearance of modern birds.

145 Million Years Ago

The earliest avialans developed around this time. The avialans were a group of theropod dinosaurs that included the closest relatives to modern birds. They exhibited feathered wings and bird-like features.

130 Million Years Ago

This period was when miniaturization began. Many theropod lineages began to see a decrease in body size over the years. Miniaturization was a crucial evolutionary step that allowed better wing-to-body weight ratios, unlocking the key to flight.

Around 120 Million Years Ago

The retention of juvenile-like features, known as paedomorphosis, played a role in the evolution of birds. The process allowed prehistoric birds to retain a more baby-like skull. These changes also enabled the transformation of facial bones into beaks.

100 Million Years Ago

The dinosaur-to-bird transition continued. Bird-like theropods, such as Microraptor and Rahonavis, exhibited advanced feather structures and an increasingly bird-like body plan. They were capable of gliding and possibly rudimentary powered flight.

85 Million Years Ago

Enantiornithes, a diverse group of ancient birds, thrived during this period. They had characteristics of both modern birds and their dinosaurian ancestors. They coexisted with other dinosaur species.

66 Million Years Ago

A catastrophic event, possibly an asteroid impact, led to the mass extinction of most dinosaur species, including non-avian dinosaurs. However, some small theropods related to birds survived.

After The Mass Extinction

In the wake of the mass extinction, birds rapidly diversified and occupied various ecological niches. They evolved into a wide range of species with diverse body sizes, beak shapes, and adaptations.

You can see a visualization of this timeline in the image below:

a chronology can be made how dinosaurs have evolved into birds

When Did Chickens Evolve?

Looking at the timeline above, you can probably ascertain that it was indeed the egg that came first, not the chicken. Over millions of years, the descendants of dinosaurs gradually evolved, gaining feathers and growing smaller, to one day for the junglefowl that would later become a member of your backyard flock. But when exactly did the first chickens appear?

Science suggests that the first chickens would have appeared between 4,000 and 10,500 years ago, but it is impossible to get an exact point in time.

It is believed, however, that domestication began in the rice fields of Southeast Asia nearly 3,500 years ago. This domestication likely started when rice was cultivated in areas where red jungle fowl (Gallus gallus), a tropical bird in the pheasant family and a precursor to modern chickens, lived. The red jungle fowl began feeding on rice grains, cultivated by local farmers, leading to the development of a familiarity between humans and these birds. This marked the initial stages of chicken domestication.

Around 2,800 years ago, chickens first arrived in the Mediterranean. These early chickens were not seen as food but as companions and were revered. Some evidence suggests that they were even buried alongside humans, indicating their social or cultural significance rather than being treated solely as a food source.

More years passed, and chickens slowly arrived in northwest Africa around 1,100 to 800 years ago. It is believed that the expansion of the chicken was linked to grain and rice cultivation. Since then, people have been selectively breeding chickens, altering their abilities, shapes, and sizes to suit a specific purpose.

What are Some Similarities Between Chickens and Dinosaurs?

red junglefowl (male)
Red Junglefowl

Now that you know that yes, chickens are dinosaurs — at least to a degree — you may be wondering how similar they are. Here are some traits that can cement the idea that chickens and dinosaurs share common DNA:

Skeletal Structure

Chickens and theropod dinosaurs share several similarities in their skeletal structure, including hind limbs and feet. Both chickens and theropods have a backward-pointing knee joint. Furthermore, chickens and dinosaurs share the primary three toes that point forward and fourth that points backwards. The backward-facing toe is often non-functional. Interestingly, the T. Rex also had this kind of toe configuration.

Cranial Features

Some theropod dinosaurs had cranial features that bear similarities to those of birds, such as eye sockets and a bony palate.


Both chickens and theropod dinosaurs are endothermic or warm-blooded, meaning they can regulate their body temperature internally. This is a significant departure from most reptiles, which are ectothermic or cold-blooded.


Chickens possess beaks, as do all modern birds. While some theropod dinosaurs had teeth, others, like oviraptorosaurs, had beak-like structures.

Nesting Behaviors

Some theropod dinosaurs, particularly those closely related to birds, are believed to have exhibited nesting behaviors similar to modern birds. This includes the arrangement of eggs in nests and possibly incubation.


Both chickens and some theropod dinosaurs laid eggs. While the size and structure of dinosaur eggs could vary significantly, the basic reproductive strategy of egg-laying is shared.

If this information is not enough for you, you can watch this video below:

Final Thoughts on Chickens as Dinosaurs

Are chickens dinosaurs? Yes, indirectly. While chickens are not the same dinosaurs that roamed the Earth millennia ago, they are indeed related. Chickens have been found to share genes with some of the greatest dinosaurs known to humankind, including Tyrannosaurs Rex. However, years of evolution have made the chicken into their own unique lifeform. Keep this in mind as you watch your flock happily clucking around that yard. Once, their ancestors may have been ruling the yard!