What Is The Closest Living Relative Of T-Rex

The Tyrannosaurus Rex was one of the world’s fiercest animals and roamed the earth 65 million years ago. Luckily for us, the T-Rex went extinct millions of years ago, but their genetics did not. Several animals alive today share genetics with the T-Rex, with some having a closer family connection than others. One animal species, in particular, can be called the closest living relative of the T-Rex, and it might be surprising to find out who this animal is.

Chickens are the closest living relatives of the T-Rex. Studies on ancient collagen sampled from a 68 million-year-old Tyrannosaurus leg bone revealed that the closest modern protein match was the chicken. The ostrich was a close second. These studies proved a link between birds and dinosaurs.

Over the years, scientists have hypothesized that birds descend from dinosaurs due to their similar appearance, among other factors. Many factors are involved in deciding which living animal is the closest living relative of the T-Rex, and it would be best to look at them all to understand why scientists have named chicken the winner.

Tyrannosaurus T-rex largest meat eating dinosaur
closest relative

Who Is T-Rex’s Closest Living Relative?

For decades scientists have hypothesized that birds and dinosaurs are distant relations to one another, with many in the scientific field believing that birds are modern-day dinosaurs. A discovery in the early 2000s changed everything, allowing scientists to have tangible evidence of the link for the first time.

A lucky find in 2003 resulted in scientists gaining access to some collagen from a 68 million-year-old T-Rex femur (leg bone). The extracted collagen was analyzed and compared to a database of living animals. The comparison results showed that the T-Rex’s closest living relative was the chicken, with the ostrich being a close second.

Before the collagen discovery, some in the scientific world had already observed that the T-Rex and modern-day chickens shared a few similar characteristics.

These characteristics included their scaly feet, sharp claws, the fact that they both walked on two feet, and that both animals had big heads with arched necks. Recent studies have also shown that some dinosaurs even sported feathers on their bodies.

The results proved that modern-day birds were descendants of dinosaurs. There are over 11,000 species of birds worldwide, and all of these birds share a common ancestor with the T-Rex, making them closer relatives to the T-Rex than even alligators or other reptiles.

Chickens and ostriches are two animals that are only distantly related but belong to the bird species. Although the studies showed that these two birds share the most protein and DNA similarities, you can consider all birds to be the actual closest living relatives of the T-Rex.

trex size

How Does The T-Rex Fit In With The Evolution Of Birds?

In the scientific world, it is a common conception that birds are technically reptiles. You may find this hard to believe, but birds share many similarities with reptiles. The scales on their feet, for one thing, and even their feathers. There is a close similarity between body tissue-producing scales and those making feathers. Birds also lay eggs, just like reptiles.

Looking at the evolutionary tree, you will see that birds belong to the family clade Maniraptora. For some background information, a clade consists of a group of animals that share a common ancestor.

All members of the Maniraptora clade share similar skeletal features, including their wrist and forelimb bone structures that they first used for grasping, which later evolved and modified into wings so that they could fly.

The Maniraptora clade consists of a group of theropod dinosaurs: Aves, the birds; Troodontids, which many believe are relatively intelligent non-avian dinosaurs; Oviraptors; Dromaeosaurs, which comprised of raptors and includes dinosaurs such as the velociraptor; and Therizinosaurs, which were plant-eating theropods.

One thing to remember when looking at an evolutionary tree and the members belonging to one of the groups on the tree is that these animals all share a common ancestry. This common ancestry means birds are not direct descendants of velociraptors or other groups of animals belonging to the Maniraptor clade. Instead, they all share a common ancestor.

When we take this information back to our discussion of what is the closest relative of the T-Rex, we can now grasp that although chickens and ostriches are the closest living relatives of the T-Rex, they are not actually descendants of the T-Rex; instead, they all share a common ancestor.

The Evolution Of The Earliest Birds

Around 150 million years ago, birds split from the other group members of their clade. While birds flourished, the other non-avian dinosaurs went extinct during the mass extinction event approximately 65 million years ago.

All birds are direct descendants of the Theropods, a group of bipedal or two-legged dinosaurs to which the T-Rex also belonged. In the beginning, Theropods were large animals with big teeth and snouts.

Over time the avian branch of theropods adapted their pre-existing features to suit their needs, acquiring large enough feathers to fly, smaller skulls and bodies, and agile beaks, all of which paved the way for modern birds.

Scientists have studied fossils stretching as far back as coelurosaurs, a subgroup of Theropods that produced dinosaurs such as archaeopteryx, to understand birds’ evolution. While the T-Rex and his buddies were giant, the ancestors of birds were shrinking.

This more diminutive stature and ability to fly probably allowed them to survive the mass extinction event that killed off their dinosaur cousins.

The survival of modern birds’ ancestors allowed them to increase in their new world devoid of other dinosaurs providing them with the space and time to evolve into modern birds.

We have a huge selection or articles to answer the common and some less common questions about the Tyrannosaurus Rex here on the site and to make it easier to access we have them in the table below.

How heavy was T-RexDid T-Rex Ever Eat PlantsT-Rex Vs. MammothDid T-Rex have Bad Eyesight
Did T-Rex RoarHow Tall was T-rexDifferences between T-Rex and VelociraptorDid T-Rex Hunt in packs
T-Rex Vs SpinosaurusHow big was a T-Rex BrainCould T-Rex Swim?Did T-Rex have Wings
Did T-Rex Lay EggsClosest living relative to T-RexTriceratops Vs. T RexHow fast could T-Rex run
How big was a T-RexT Rex Facts


Studies on ancient collagen from a 68 million-year-old T-Rex femur show that the T-Rex’s closest living relatives are birds, with chickens and ostriches showing the most immediate family connection. These studies proved a common hypothesis that birds are living dinosaurs.

The close connection between birds and the T-Rex does not mean that birds are direct descendants of the T-Rex, but instead that the two species share a common ancestor that split to produce the T-Rex line and the line that eventually evolved into modern birds.


Similar Posts

Leave a Reply

Your email address will not be published. Required fields are marked *