Why did some fish grow legs?
Some fish began to live in shallow water. It was difficult to swim in the shallows. To help these fish move around they grew short legs. Some of them also grew lungs, which meant they could breathe air. These animals could live in water and on land.
The lungfish is one of today’s fish that can live out of water. It can breathe air.
Which animal lives in water and on land?
An animal that can live in water and on land is called an amphibian. It means ‘double life’. The first amphibians appeared by 350 million years ago. Gradually, they spent more and more time on land.
What are reptiles?
About 300 million years ago, some amphibians changed into reptiles. They could live on land all the time. Reptiles have backbones and scaly skin, and most lay eggs. Many reptiles, such as crocodiles, spend lots of time in the water, but they can’t breathe underwater. They use the Sun to keep their bodies warm.
Is it true?
Some early reptiles had sails on their backs.
Yes. Dimetrodon had a skin ‘sail’ on its back. It soaked up the Sun’s heat, and controlled the animal’s body temperature.
What did reptiles eat ?
The first reptiles, such as Hylonomus, were small lizard-like animals that ate tiny creatures. Reptiles learned how to run quickly so they could catch fast-moving insects. As reptiles became larger, they caught and ate bigger prey, including other reptiles. Some reptiles only ate plants.
A small animal found in Scotland, in rocks that are 350 million years old, might be one of the first reptiles. But some scientists say it was an amphibian.
Which reptiles had fur?
Some prehistoric reptiles grew fur on their bodies to keep themselves warm. These were the cynodonts. They lived about 245 million years ago. Over time they changed into a completely new group of animals, called mammals.