Prehistoric Animals


Prehistoric animals lived more than 5,000 years ago before people could read or write. Some of them looked a lot like the animals we can see today. But others were very different from the ones that live on our Earth now. Great dinosaurs that were up to 40 meters long and big flying reptiles with wingspans of 12 meters were among them.

Scientists have learned a lot about these prehistoric animals by studying fossils. They are signs of life that can be found inside an old rock. They may be shells, bones or animal tracks. Scientists remove the fossils from the rock and study them. By doing this they can tell where, when and how the animals lived.



Prehistoric animals lived during three main eras of the Earth’s history.

  • Up to the Paleozoic period animals lived mostly in the seas. During this era, which lasted from about 600 million to 240 million years ago, animals started coming out of the water and living on land. Many forms of life developed during this time, like insects and small reptiles. Amphibians were creatures that lived on land and in the water.
  • The Mesozoic era was known as the Age of Reptiles. It lasted from about 240 million to 65 million years ago. At the end of this age the dinosaurs and many other reptiles died out. Scientists do not know for sure why they died out so quickly, but some think it was because of a sudden change in climate.
  • The Cenozoic era is known as the Age of Mammals. It began about 65 million years ago and is the period we now live in. Mammals are animals that feed their babies with their mother’s milk. The most famous mammal was the mammoth.



Related Topics


  • develop = grow
  • fossil = the bones of an animal or plant that lived thousands of years ago; it has been preserved in rock
  • mammoth = a hairy large elephant that lived on our Earth thousands of years ago
  • prehistoric= the time in history before anything was written down
  • reptile= animal like a snake whose body temperature always changes; it lays eggs to have babies
  • sudden = quickly
  • track = prints in the ground