Which Dinosaurs Survived After the Asteroid Hit Earth?

When people imagine the end of the dinosaurs, they often picture Tyrannosaurus rex, Triceratops, Velociraptor and other giant reptiles disappearing forever after a massive asteroid struck Earth. But there is an incredible twist to this story: dinosaurs did not completely disappear.

One group of dinosaurs survived the catastrophe—and their descendants are still flying, walking and singing around us today.

Birds are living dinosaurs.

The asteroid impact happened about 66 million years ago, at the end of the Cretaceous Period, not the Jurassic Period. The Jurassic Period ended roughly 145 million years ago. This distinction is important because many famous dinosaurs, such as T. rex and Triceratops, lived during the later Cretaceous rather than the Jurassic. (Natural History Museum)

So, which dinosaurs actually survived?

The Asteroid That Changed Earth Forever

Around 66 million years ago, an enormous asteroid struck what is now Mexico's Yucatán Peninsula. The impact created the gigantic Chicxulub crater, which is approximately 150 kilometers wide. Scientists estimate that the asteroid itself was roughly 10–15 kilometers across. (Natural History Museum)

The collision released an enormous amount of energy.

Tsunamis swept across coastlines. Fires spread across large areas. Dust, ash and other material entered the atmosphere and blocked sunlight. Temperatures changed dramatically, while the collapse of vegetation disrupted food chains around the world. (Natural History Museum)

Scientists estimate that roughly three-quarters of Earth's species disappeared during this mass extinction.

The giant non-avian dinosaurs were among the victims.

But one branch of the dinosaur family tree survived.

Birds: The Dinosaurs That Made It

The dinosaurs that survived were avian dinosaurs—the ancestors of modern birds.

Birds evolved from small theropod dinosaurs, the same broad dinosaur group that included famous meat-eaters such as T. rex. The earliest bird-like dinosaurs appeared more than 150 million years ago during the Jurassic Period. (Natural History Museum)

By the end of the Cretaceous, Earth already had many different types of birds.

Some were very different from modern birds. Certain ancient birds had teeth, while others had beaks. Some lived near the ocean, and others lived on land.

However, most of these ancient bird groups also disappeared during the extinction.

Only a few evolutionary lineages managed to survive.

Were T. rex or Triceratops Survivors?

Unfortunately, no.

There is no convincing evidence that Tyrannosaurus rex, Triceratops, Stegosaurus, Diplodocus or other famous non-avian dinosaurs survived beyond the Cretaceous-Paleogene extinction.

The extinction was not simply the disappearance of the biggest dinosaurs. All known non-avian dinosaur lineages disappeared, while one branch of dinosaurs—birds—continued into the following Paleogene Period. (Natural History Museum)

This means that technically, if you see a sparrow, eagle, pigeon, chicken or ostrich today, you are looking at a modern descendant of dinosaurs.

Why Did Some Birds Survive?

This is one of the biggest mysteries surrounding the extinction.

Scientists believe there wasn't one simple reason.

Several characteristics may have increased the survival chances of certain birds.

1. Small Body Size

Many of the birds that survived were relatively small.

Large animals generally require more food and energy. After the asteroid impact, ecosystems experienced an enormous food shortage. Smaller animals could potentially survive with fewer resources. (Natural History Museum)

Imagine an ecosystem suddenly losing much of its vegetation.

A giant herbivore might need hundreds of kilograms of food.

A small bird requires dramatically less.

That difference could become extremely important during a global ecological crisis.

2. Different Food Sources

The asteroid didn't simply kill animals directly. It also damaged ecosystems.

Forests were devastated, sunlight was reduced and plants died. This meant herbivores lost their food, followed by carnivores that depended on those herbivores.

Some surviving birds may have been able to eat seeds and other relatively durable foods that remained available after forests were destroyed.

Their beaks and powerful digestive systems may have helped certain species process tough foods such as seeds. (Smithsonian Magazine)

This could have given them an advantage during the period when normal vegetation was collapsing.

3. Ability to Fly

Flight may also have helped.

Birds could move across large distances in search of food and suitable habitats. After the disaster, being able to relocate could have been extremely valuable.

Scientists believe mobility and the ability to colonize new environments contributed to the survival and later diversification of birds. (Natural History Museum)

However, flight alone wasn't enough.

Many flying bird groups still became extinct.

Survival depended on a combination of characteristics—and probably some luck.

The "Wonderchicken"

One fascinating example is Asteriornis maastrichtensis, sometimes nicknamed the "wonderchicken."

Fossils of this ancient bird date to approximately 66.7 million years ago, only around 700,000 years before the mass extinction.

It was a relatively small, ground-dwelling bird with characteristics associated with modern bird groups. Scientists think its descendants may be connected to lineages that eventually produced birds such as chickens and ducks. (Natural History Museum)

The wonderchicken provides scientists with an important clue: some of the evolutionary branches leading toward modern birds already existed shortly before the asteroid struck.

Three Major Bird Lineages Survived

Research suggests that the ancestors of several major modern bird groups made it through the extinction.

These include:

• Palaeognathae — the lineage containing ostriches, emus and related birds

• Galloanserae — the lineage containing chickens, ducks and related birds

• Neoaves — the enormous group containing most living bird species

The survivors were not necessarily identical to modern birds. They were ancient species that belonged to evolutionary lineages that eventually produced today's enormous diversity of birds. (Natural History Museum)

What Happened After the Extinction?

Once the non-avian dinosaurs disappeared, the ecological landscape changed dramatically.

The dinosaurs had dominated terrestrial ecosystems for more than 160 million years. Suddenly, many ecological niches were empty.

Mammals began diversifying rapidly.

Birds also expanded into new environments.

Over millions of years, surviving bird lineages evolved into thousands of different species. Today, there are more than 10,000 living bird species, occupying environments ranging from tropical forests and deserts to oceans and polar regions. (Natural History Museum)

Some eventually became enormous.

Others became tiny.

Some became powerful predators.

Others specialized in seeds, fruits, insects or nectar.

The diversity of modern birds is therefore part of the long evolutionary story that began with small feathered dinosaurs.

Did Any Other "Dinosaur-Like" Animals Survive?

This is where terminology becomes important.

Pterosaurs were not dinosaurs, even though they are often incorrectly called flying dinosaurs. They were a separate group of flying reptiles, and they also disappeared around the K-Pg extinction. (Natural History Museum)

Similarly, marine reptiles such as mosasaurs and plesiosaurs were not dinosaurs, and they also disappeared.

So the answer is surprisingly simple:

No non-avian dinosaur is known to have survived the asteroid-driven mass extinction. The surviving dinosaurs were birds and their evolutionary ancestors.

The Dinosaur That Lives in Your Backyard

Perhaps the most amazing part of the story is that dinosaurs are not really extinct.

When a crow lands on a wall, a hawk circles above a field, or a chicken walks across a farmyard, you are seeing the descendants of an ancient dinosaur lineage.

The modern bird may look nothing like a T. rex, but evolutionary history connects them.

Birds inherited important dinosaur characteristics, including aspects of their skeletons, feathers and overall evolutionary ancestry. Scientists therefore classify birds as avian dinosaurs, while dinosaurs such as T. rex and Triceratops are called non-avian dinosaurs. (Natural History Museum)

Conclusion

The asteroid that struck Earth 66 million years ago ended the reign of the giant non-avian dinosaurs—but it did not eliminate dinosaurs completely.

Small bird-like dinosaurs survived the catastrophe.

From those survivors eventually came the extraordinary diversity of modern birds.

So the next time you see a pigeon, eagle, crow or chicken, remember: you aren't just looking at a bird.

You are looking at one of the last surviving branches of the dinosaur family tree.

The age of giant dinosaurs ended 66 million years ago—but their story never truly ended.

The dinosaurs are still here. They just learned to fly.