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LET'S EXPLORE Prehistoric life

When did the first dinosaurs appear?

A Triassic archosaur running on its back legsA Triassic archosaur running on its back legsThe archosaurs were a group of reptiles that had powerful jaws and bony armour. Somehow they survived the Great Dying at the end of the Permian. Early archosaurs ran like modern lizards do. Some kinds evolved longer legs and ran faster. By the middle of the Triassic Period, 230 million years ago, a few could run on their two back legs all the time. The first dinosaurs had evolved.

Reptiles' standing positions comparedReptiles' standing positions compared

What is a dinosaur?

Dinosaurs were reptiles that lived on land in the Triassic, Jurassic or Cretaceous periods (230 to 66 million years ago). They walked upright like mammals or birds, not sprawling like lizards or crocodiles. Dinosaurs lived only on land. Neither marine reptiles nor flying reptiles (pterosaurs) were dinosaurs.

Triassic South America

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

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