Discovery Of Dinosaurs

How Did Dinosaurs Extinct

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What Happened To The Dinosaurs?

Dinosaurs were going extinct the whole time they roamed the earth. But as one kind of dinosaur disappeared, others filled its place (Dinosaurs closest relatives, birds, didn't die out.) What stopped this evolutionary parade of dinosaurs? Space rocks!

At least, many scientists now think so. Twenty years ago, scientists begin finding evidence that asteroids, rocks from space, crashed into Earth 65 million years ago. One huge crater, from just such an impact, has been found on the ocean floor in the Gulf of Mexico. That crater is 50 to 60 miles (80 to 110 kilometers) wide in the impact center. It could be 168 miles (270 kilometers) wide at its outer rim!

When asteroids hit Earth, they sent huge clouds of dust-up into the air.

The dust from a giant asteroid would have blocked the sunlight and changed Earth's temperature. The heat of the asteroid as it burned through Earth's atmosphere would have set fires blazing. Smoke, heat and clouds of ash would have spread across the planets.

Around the time that the asteroids hit, roughly 65 million years ago, many kinds of animals died out. Dinosaurs, as well as the giant reptiles of the sea and air, were among the life forms wiped out in this great extinction. Birds, descended from meat eating dinosaurs, lived on. Mammals, reptiles such as crocodiles, insects such as cockroaches, and many other kinds of life on sea and land also mysteriously survived.

Asteroids and weather changes might not have been the only causes of dinosaur extinction. At the end of the Cretaceous Period, seas were drying out. Changes in the sea levels may have created more extreme winter and summer weather in all lands. Other weather changes, caused by volcanoes or shifting sea currents, may have also affected the earth and its inhabitants.

Continents long separated were coming together again, too. Maybe mammals or other animals carried deadly diseases with them as they crossed newly linked landmasses. Animals that had been separated for so long would not be immune to each other's diseases. Any of these slow changes may have been as much the cause of the dinosaurs extinction as the asteroid impact.

We don't know exactly what killed the dinosaurs. Maybe we will never have definite proof. But we do know enough about these amazing animals to picture them in our minds and appreciate how extraordinary dinosaurs were. We humans didn't come along until 64 million years after the last dinosaurs had died yet they lived on in our books, our movies, and our dreams.