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Do dinosaurs still exist in some parts of the world today? – Ruben M., 5 years old
Did all the dinosaurs become extinct when an asteroid hit the Earth 66 million years ago? Or could some of them, in some way, have survived that mass destruction event – and their descendants live even today?
It’s exciting to imagine that giant dinosaurs still roam and lumber around in some remote part of the world. But there is no evidence of this. He has no cousins Tyrannosaurus rex passing through the great forests of Siberia, no Apatosaurus walking through the Congo rainforest.
As a paleontologist, I have spent much of my life studying ancient animals, especially dinosaurs. But I saw only fossils of these creatures, nothing alive – with one exception. One group of dinosaurs is still around. To find them, just go outside and look up.
The asteroid killer
In 1977, the American geographer Walter Alvarez was working in the Apennine mountains in Italy. There, he found a thin layer of clay with an unusual amount of a metal called iridium in it. The clay was between rocks from the Cretaceous and Paleogene periods and dates from when the dinosaurs disappeared.
Iridium is rare on earth but more common in some meteorites. Working with his father, Luis, who was a Nobel Prize-winning physicist, Walter Alvarez developed the theory that a giant space rock – an asteroid – collided with Earth 66 million years ago. This impact left traces of iridium all over the world and triggered the unimaginable catastrophe that killed the dinosaurs and many other species of animals and plants on land and in the sea.
At first, many scientists rejected the theory. But then, in 1991, geologists discovered a huge crater buried under the seabed off Mexico’s Yucatan Peninsula. This was the spot where an asteroid, about 6 miles (10 kilometers) across, crashed into our planet 66 million years ago.
The collision was so powerful that it sent a trillion tons of dust and molten rock into the sky. Many pieces of molten rock fell back to Earth, causing huge wildfires everywhere. A thick blanket of dust in the atmosphere blocked most of the sunlight, resulting in freezing temperatures around the world. Earth turned into a cold, desolate place for many years, even centuries.
The loss of sunlight killed many plants. With no food available to them, large dinosaurs like to eat plants Triceratops expired quickly. That left large predators as Tyrannosaurus rex not eating prey animals, so they died, too.
But small animals like mammals, lizards and turtles could adapt. They could hide in holes and live on a wide variety of food. Fish lived in rivers and lakes and were protected by their watery homes. And they survive: birds, the only remaining dinosaurs.
The bird connection
Fast forward about 66 million years: Scientists noticed in the 19th century that the skeletons of both modern birds and dinosaurs were fossilized in many ways. The similarities in the legs and feet were particularly striking. However, most scientists then thought that dinosaurs and birds were too different to be related to each other.
Then, in 1964, dinosaur expert John Ostrom discovered the dinosaur’s fossils Deinonychus. It had a mouth full of sharp teeth with serrated edges like steak knives, long slender hands with three fingers ending in large curved claws, and a huge claw on the second toe of each foot. A fast hunter who did not conform to the traditional ideas about dinosaurs being so slow and not very active, Deinonychus it lived in North America during the Cretaceous period, about 110 million years ago.
For another research project in the early 1970s, Ostrom examined the earliest known bird, ie. Archeopteryxwhich lived 150 million years ago in what is now Germany. It had feathered wings and wishbones, as well as reptilian-like characteristics, including jaws with sharp teeth, hands with three fingers each, and a long tail.
Compare this ancient bird with DeinonychusOstrom realized that their skeleton had many special features. For example, both had unusually long hands and arms, very flexible wrists, hollow bones and an S-shaped neck.
Based on these and many other similarities, Ostrom showed that birds are descended from small bird-eating dinosaurs.
In the past twenty years, paleontologists have found many skeletons of ancient birds and bird dinosaurs in Jurassic and Cretaceous rocks in China. Surprisingly, the birdlike dinosaurs, including close relatives Deinonychuscovered with feathers, just like the birds that live with them. Paleontologists now agree that many, if not all, dinosaurs maintained a high body temperature, just as birds and mammals do today. Feathers kept them warm.
Bird-like dinosaurs didn’t make it through the extinction event 66 million years ago – but some of the early birds that lived alongside them did. And they came into the birds alive today.
Remember that: to see a dinosaur, all you have to do is glance at the sky. And as someone who has studied dinosaurs for a long time, I am glad to know that I share the world with dinosaurs.
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This article is republished from The Conversation, a non-profit, independent news organization that brings you reliable facts and analysis to help you make sense of our complex world. It was written by: Hans Sues, Smithsonian Institution
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Hans Sues currently receives funding from the Smithsonian.
