Dinosaurs were reptiles that lived during a period of earth’s history called the Mesozoic Era, which is also known as the Age of Reptiles. The first dinosaurs appeared more than 200 million years ago. For many millions of years, they dominated the land with their huge size and strength. Then about 65 million years ago, they died out rather suddenly, never to re-emerge.The word “dinosauras” comes from two Greek words meaning “terrible lizard”. Dinosaurs were not lizards, but their appearance could be truly terrifying. The biggest ones weighed more than ten times as much as a mature elephant and nearly equalled the size of most modern-day whales. The famous kinds of dinosaurs, including the brontosaur and tyrannosaurus rex, reached 80 to 90 feet in length. Not all dinosaurs were giant, however, some were actually not larger than a chicken.Scientists still do not know what caused dinosaurs to disappear. One theory involves a change of the earth’s climate. It is believed that temperatures dropped significantly towards the end of the Cretaceous protection, it is possible that the climate became too chilly for dinosaurs. In contrast, other species having protection, such as the mammals and birds, were able to survive.
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