Long ago, the world was very different than it is now. Today, all the land on earth is divided into seven continents. Millions of years ago, there was just one continent.
A continent is one of the earth’s large land masses.
Scientists have named that ancient continent Pangaea (pan-JEE-uh).
Some parts of Pangaea were very dry, like deserts. Other parts were damp and rainy, like swamps. There were forests and jungles, plains and mountains, rivers and lakes.
And there were dinosaurs almost everywhere.
Some dinosaurs were bigger than buildings. Others were as small as ducks.
Some dinosaurs walked on all four legs, like dogs. Others walked on two legs, like people.
Some dinosaurs had many rows of sharp teeth. Others had no teeth at all.
But in some ways, all dinosaurs were alike.
They all were reptiles. They all lived on land. They all laid eggs. They almost all had scaly skins. None of them had fur or hair.
Dinosaurs
Reptiles
Lived on land
Laid eggs
Scaly skin
No fur or hair
Reptiles are cold-blooded, usually scaly-skinned animals. Snakes, turtles, and lizards are reptiles.
Scientists think that the first dinosaur hatched over 225 million years ago. They say almost all the dinosaurs died about 65 million years ago. That means there were dinosaurs on earth for more than 160 million years!
Almost all the dinosaurs lived during what is called the Mesozoic (mez-uh-ZO-ick) Era. Scientists also call this time the “Age of Reptiles” or the “Age of Dinosaurs.”
Scientists divide the Mesozoic Era into three parts, or periods. The first is the Triassic (try-AA-sick) Period. The middle is the Jurassic (jur-AA-sick) Period. The last is the Cretaceous (krih-TAY-shus) Period.
Different kinds of dinosaurs lived in each period. The ones we know best today lived during the Jurassic and Cretaceous periods. That’s over 60 million years before the first human was born.
So how can we know about these dinosaurs if no human has ever actually seen one?
We know about them because they left their bones and teeth and footprints all over the world.
