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| DINOSAURS. A Mystery Disappearance. |
Many of the dinosaurs that once roamed the world were therefore big and strong that they did not need to be afraid of any living thing. So why are there no dinosaurs today?
Some scientists suppose that when new styles of plants began to grow on Earth, dinosaurs could not eat them. New kinds of animals smaller than dinosaurs also appeared during this time they may have been able to survive better than the dinosaurs. It's also possible that disease killed them by the millions.
Not all scientists suppose that all dinosaurs died at once. Another rationalization is that an ever-changing climate killed them. We know that when they were living, the weather began to change. Summers grew shorter and winters grew colder. In some places, heat waves dried up rivers and swamps. Elsewhere, new lakes and rivers appeared, and plenty of places were flooded. Some dinosaurs could have died as a result of it gradually became too cold or too hot for them.
Several scientists believe that dinosaurs died
as a result of an asteroid struck the Earth about sixty five million years ago.
The dust raised by the impact would have blocked out daylight for months, in
order that plants stopped growing and therefore the temperature dropped. As a
result, plant-eating dinosaurs would have died from lack of food, as would the
meat eaters that hunted them.
Some scientists think that several dinosaurs evolved into birds. So the next time you see a robin, take into account that you may be looking at a dinosaur's relative.
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| DINOSAURS. A Mystery Disappearance. |
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