Why are chickens called the closest relatives of dinosaurs
When we think of dinosaurs, fierce giants like Tyrannosaurus rex (T. rex) or long-necked sauropods usually come to mind. However, not all dinosaurs went extinct about 66 million years ago at the end of the Cretaceous Period. In a remarkable twist of evolutionary history, one group of dinosaurs survived and evolved into birds, making modern birds, chickens included, the closest living relatives of dinosaurs. According to the study by Harvard Health, molecular comparisons showed that T. rex proteins are most closely related to modern birds such as chickens and ostriches, providing the first molecular evidence that birds are the closest living relatives of dinosaurs.
The dinosaur-bird connection
In paleontology, the classification of dinosaur fossils can be broken down into non-avian dinosaurs, which refers to the extinct group of reptiles T. rex, Velociraptor, among others, and the group of avian dinosaurs, which we refer to as birds. Scientific evidence supports the notion that birds are, in fact, a subset of the dinosaur group.This implies that when you observe a chicken pecking away in a farm yard, you are actually looking at a direct descendant of a dinosaur species who managed to survive an event called mass extinction when all non-avian dinosaurs became extinct.
Fossil evidence: From feathered dinosaurs to birds
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One of the strongest evidence for the link between birds and dinosaurs has come from the fossil remains of small meat-eating dinosaurs discovered in China and other countries that have fossils of feathers. These types of dinosaurs, known as feathered theropods (a family of dinosaurs that includes Velociraptors), have traits that lie somewhere between reptilian and birds.Elements such as feathers, hollow bones, and three-toed feet appear first in these dinosaur fossils and later in early bird species, indicating a clear evolutionary transition.
Anatomical similarities between birds and dinosaurs
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Scientists have identified numerous common traits (called synapomorphies) between dinosaurs and modern birds:Hollow bones: lightweight structures aiding movement and flight.Furcula (wishbone): the fused collarbone found in birds that also existed in theropod dinosaurs.Three-toed feet and similar limb arrangements: shared skeletal patterns between birds and theropods.These similarities are not superficial but rather deep structural features that support a common ancestry.
Molecular (protein) evidence
Researchers were able to isolate pieces of collagen protein from a T. Rex fossil and match them with proteins from modern organisms. What was surprising was that the best matches were obtained with proteins from chickens and ostriches, thus proving that birds evolved from theropod dinosaurs.Although it’s not possible to retrieve the entire DNA of dinosaurs, the study of available protein evidence has helped confirm the idea that chickens and the rest of the bird family are the closest living relatives of non-avian dinosaurs like T. rex.
Clarifying a common misunderstanding
It’s important to understand that chickens did not evolve directly from T. rex. Rather, T. rex and chickens share a common ancestor within the broad group of theropod dinosaurs. Birds branched off from that family tree much earlier, and over millions of years of evolution, they developed the features we associate with modern birds.Chickens are regarded as the closest living relatives of dinosaurs because:Birds evolved directly from a group of theropod dinosaurs.Fossils show transitional features linking birds to dinosaurs.Molecular studies confirm similarities between dinosaur proteins and bird proteins.This very interesting evolutionary story showcases how this particular line of an ancient species not only survived through times of catastrophe but also became so diverse as to consist of thousands of species of birds as we see today. So the next time you see a chicken parading about in front of your very eyes, remember this, you are witnessing an evolutionary survivor who in times past lived on Earth as a dinosaur.
