When you think of fossils and prehistoric times, many probably think of the many "terrible lizards" we know as dinosaurs.
They still fascinate children and adults today.
Dinosaurs ruled the Earth for millions of years. But they weren't the first to do so...there were animals that roamed our world long before them.
In fact, life existed hundreds of millions of years before the dinosaurs. Early life forms existed in many different shapes and sizes!
The earth has experienced different forms of environment.
Some of the most surprising life forms existed in the Carboniferous.
At that time, the land was covered with hot, humid swamps and tropical forests. These places were populated by different kinds of amphibians and giant insects!
During the next period, the Permian, the land became hotter and drier and vast desert areas saw the birth of strange new species like the Dimetrodon, a mammal-like carnivorous predator with a huge sail on its back.
Over time the gap has narrowed between the large amphibians and the first dinosaurs...