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Age of Dinosaurs

Age of Dinosaurs

Dinosaurs of Jurassic North AmericaDinosaurs of Jurassic North America The Triassic, Jurassic and Cretaceous periods, which lasted from 252 to 65.8 million years ago, are together known as the Mesozoic Era, but more commonly called the Age of Dinosaurs. The Palaeozoic, the previous era, ended with the greatest mass extinction of life the Earth has ever known, in which more than 90% of species were wiped out. The disappearance of large amphibians and many other types of reptiles opened the way for the archosaurs, the group of reptiles which dinosaurs, crocodiles and pterosaurs evolved from, to dominate life on Earth.

North America about 300 million years ago North America about 300 million years ago

Before the dinosaurs

The story of the dinosaurs began long before they first appeared about 230 million years ago. Their evolution can be traced back to fish, the first vertebrates. About 360 million years ago, some kinds of fish developed the ability to crawl on to land, and so gave rise to amphibians. These animals still kept close to water, where they laid their jelly-covered eggs. It took another 50 million years for some creatures, the first reptiles, to find a way of laying their eggs on land. Gradually the reptiles spread across the world, and, being perfectly suited to the new drier conditions, they became the dominant type of animal on land. 

Evolution of the dinosaurs

Dinosaurs lasted for about 165 million years. Modern humans, by comparison, have been around for just 300,000 years.

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