Did all the dinosaurs become extinct when an asteroid struck Earth 66 million years ago? Or did some dinosaurs somehow survive that mass extinction and their descendants are still alive today?
It’s exciting to imagine giant dinosaurs still rumbling about in some far-flung corner of the world, but there’s no evidence for it. Tyrannosaurus Rex Roaming the vast forests of Siberia, Apatosaurus Walking through the Congo rainforest.
As a paleontologistI’ve spent most of my life studying ancient animals, especially dinosaurs. But I’ve only ever seen fossils of these creatures, never living ones. With one exception: one group of dinosaurs is still alive today. To find them, just go outside and look up.
Ankylosaurus was a herbivorous dinosaur with armor and a tail club that could kill any attacker. (Photo by Daniel Eskridge/iStock via Getty Images Plus)
Killer Asteroid
In 1977, American geologist Walter Alvarez While working in the Apennine Mountains in Italy, he discovered a thin layer of clay there that contained unusual amounts of metal. iridium The clay was among the rocks Cretaceous and PaleogeneThe period and date since the extinction of the dinosaurs.
Iridium is rare on Earth, but is more common in some regions. meteoriteHe worked with his father, Louis. Nobel Prize-winning physicistWalter Alvarez is a giant space rock, i.e. asteroid66 million years ago, a meteorite struck the Earth. The impact left traces of iridium all over the world and caused an unimaginable disaster, wiping out the dinosaurs and countless other plant and animal species on land and in the sea.
Initially, many scientists dismissed this theory, but in 1991, geologists discovered a huge crater on the ocean floor off the coast of Mexico’s Yucatan Peninsula, where an asteroid roughly six miles (10 kilometers) in diameter had impacted. It collided with Earth 66 million years ago.
The impact was so powerful that it sent trillions of tons of dust and lava into the sky. Much of the lava fell to Earth, sparking massive wildfires across the globe. A thick layer of dust in the atmosphere blocked out most of the sunlight, causing subzero temperatures around the world. Earth became a cold, desolate place. For years, for centuries.
The decrease in sunlight caused many plants to die. With no food available, the large herbivorous dinosaurs Triceratops They quickly became extinct. As a result, Tyrannosaurus Rex With no prey animals to eat, they too died out.
But small animals Mammals, lizards and turtles can adaptThey hid in burrows and lived off a variety of foods. Fish lived in rivers and lakes, protected by their aquatic homes. And with them, the only surviving dinosaurs were birds.
Adult Deinonychus could weigh up to 220 pounds (100 kilograms). (Credit: SCIEPRO/Science Photo library via Getty Images)
Connecting with birds
Fast forward about 66 million years, and in the 19th century, scientists were wondering how the skeletons of modern birds and fossil dinosaurs matched up. were similar in many waysThe similarities in the legs and feet were particularly striking, but most scientists at the time thought dinosaurs and birds were too different to be closely related.
And in 1964, Dinosaur expert John Ostrom dinosaur fossils discovered DeinonychusIt had a mouth full of sharp, serrated teeth like steak knives, long, slender hands with three fingers ending in large, curved claws, and a huge claw on the second toe on each foot — a departure from the conventional notion of dinosaurs as slow, inactive creatures — making it a nimble hunter. Deinonychus It lived in North America during the Cretaceous period, about 110 million years ago.
In another research project in the early 1970s, Ostrom discovered that ArchaeopteryxIt lived 150 million years ago in what is now Germany and had reptilian features, including feathered wings, a wishbone, jaws with sharp teeth, three-fingered hands and a long tail.
This ancient bird DeinonychusOstrom noticed that their skeletons shared many similarities: both had unusually long arms and hands, highly flexible wrists, hollow bones, and S-shaped necks.
Based on these and many other similarities, Ostrom suggested that birds descended from small, predatory bird-like dinosaurs.
With its sharp teeth and long, bony tail, Archaeopteryx is a link between dinosaurs and modern birds. (Photo by Leonello Calvetti/Science Photo Library via Getty Images)
Over the past 30 years, paleontologists have uncovered numerous skeletons of ancient birds and bird-like dinosaurs in Jurassic and Cretaceous rocks in China. Remarkably, some of the bird-like dinosaurs had DeinonychusThey were covered in feathers, just like the birds that lived at the time. Paleontologists now agree that many, if not all, dinosaurs maintained a constant, high body temperature, just like modern birds and mammals. Feathers kept them warm.
While bird-like dinosaurs did not survive the extinction 66 million years ago, some of the early birds that coexisted with the dinosaurs did survive – and evolved into birds that live today.
Think about it: all you have to do to see dinosaurs is look up at the sky, and as someone who has studied dinosaurs for a long time, I’m glad that we live in the same world as dinosaurs.
Hans Suess is senior research geologist and curator of vertebrate paleontology at the Smithsonian Institution. This article is conversation Under Creative Commons License.Please read Original article.
