My Science School

It takes millions of years to make a fossil. An animal dies. Its body sinks to the bottom of a lake. Sand and silt cover its body. The flesh rots away. Minerals seep into the bones and turn them to stone. The animal is now a fossil. The fossil is found.

How do we know about life in the past?

We find out about life in the past by looking for evidence. Fossils are one kind of evidence. They are the remains of living things that have been preserved. Objects made by humans, such as stone tools, are another kind of evidence.

Is it true? Plants can’t be fossilized.

No. Plants can become fossils, in the same way that animals can. By studying them we learn about the plants that once grew on Earth.

Who looks for prehistoric life?

People who look for remains of prehistoric animals, such as dinosaurs, are called palaeontologists. People who look for ancient humans are archaeologists. They find great things, such as bones, tools, buildings, jeweller and weapons.

Amazing! A sticky resin that oozed from pine trees trapped insects that landed on it. It hardened into a substance called amber. Prehistoric insects are perfectly preserved inside it.

Just over 100,000 years ago Homo sapiens appeared. The name means ‘wise man’. They were modern humans. In Europe they lived during the freezing Ice Age, a time when glaciers covered the land. The Ice Age ended 12,000 years ago.

Is it true? Homo sapiens have all died out.

No. All people on Earth today are members of Homo sapiens. If they had died out, like other kinds of early human, none of us would be here today!

Where did they live?

Homo sapiens first appeared in Africa, and from there, they spread out across the world. They lived in cave entrances, and in places sheltered by overhanging rocks. In the open they made huts from branches, covered with skins.

Amazing! People who lived during the Ice Age played musical instruments. They made whistles from bones, and drums from shoulder-blades.

Were they artists?

The humans who lived in Europe during the Ice Age were among the first artists. They painted pictures of horses, bison and deer on the walls of their caves. Bone and ivory were carved into figures of animals and people.

The first people we think of as humans appeared in Africa. About two million years ago, Homo habilis (handy man) appeared. Then, more than one million years ago, Homo erectus (upright man) appeared, but they weren’t modern humans.

Did they have any tools?

Homo habilis was the first tool-user. This is why he is called ‘handy man’. He made simple tools, such as choppers, from pebbles. The tools made by Homo erectus were better. He shaped stones into hand axes, and he was the first to use fire.

What did they eat?

Homo habilis and Homo erectus ate meat and plants. Meat probably came from dead animals which they found. They may have hunted for some small animals. Plants gave them berries and leaves. They used stone tools to cut and scrape their food.

Amazing! Homo erectus had fire. Fire provided warmth, gave heat for cooking, and offered protection from predators.

Is it true? Homo erectus was a wanderer.

Yes. More than one million years ago, Homo erectus began to move out of Africa, travelling to Europe and Asia.

Mammals have backbones, their bodies are covered in hair or bristles, they make their own body heat, and they feed their young on milk. They have larger brains than most other animals.

When did the first mammals appear?

The first mammals appeared on Earth about 220 million years ago. They lived at the same time as the dinosaurs. Mammals survived after the dinosaurs died out, and then they became the ruling animals on Earth. There are about 4,200 different kinds of mammals alive today.

Amazing! Woolly mammoths were big elephants with extra-long tusks up to 3 metres long. Their bodies were covered in fur.

Did mammals only live on land?

Mammals came to live in all of Earth’s habitats. Many lived on land, but some, such as bats, were able to glide through the air on wings of skin. Other mammals swam in the sea, such as whales, dolphins and seals.

Is it true? The elephant is the largest land mammal ever to have lived.

No. Indricotherium was the largest land mammal. It was almost 8 metres tall and as heavy as four elephants.

Picture Credit : Google

Birds are animals with backbones; they lay eggs, can make their own body heat, and have wings. They are also the only animals with feathers. Not all birds can fly. The first birds lived at the same time as the dinosaurs.

Is it true? Ostrich eggs are the biggest eggs ever laid by a bird.

No. The extinct bird Aepyornis laid the biggest eggs of all time. Each one was about the size of 150 hen’s eggs.

Where do birds come from?

Birds evolved from small, meat-eating dinosaurs. Fossils show that some of these dinosaurs had feathers. They are called ‘dinobirds’. The first ‘dinobirds’ probably could not fly.

Amazing! Today’s hoatzin bird, which lives in South America, has claws on its wings when young - just like Archaeopteryx, its prehistoric ancestor did.

Which was the first true bird?

The first true bird - a bird that could fly - appeared about 150 million years ago. It is known as Archaeopteryx, which means ‘ancient wing’. It had claws on its wings.

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.

Amazing! 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.

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.

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.

Picture Credit : Google

Life on Earth began about 3.5 billion years ago. The first life appeared in the sea. It was born into a world that looked very different from today. The atmosphere was filled with poisonous gases. The sky was pink, and the sea was rusty-red.

Is it true? Earth is the only planet with life on it.

Maybe. This is one of the greatest unsolved mysteries. Life probably does exist on other planets besides Earth, but nothing has been found so far. The search continues.

How did life begin?

It is thought that life began when lightning hit the sea. Lightning sent energy into the water. Chemicals in the sea were mixed together by energy. New substances, called amino acids, were made, from which life was able to grow.

Amazing! The first living things on Earth were so small you could fit thousands of them on the head of a pin.

What were the first living things?

The first living things were bacteria. They lived in the sea. Some bacteria changed into algae, which were simple plants. Algae lived in the sea in masses, like huge blankets. They made oxygen, which helped to turn the sky and sea blue.

Picture Credit : Google

About 440 million years ago, the first life appeared on land. It was simple plant life, similar to today’s mosses. Then, about 400 million years ago, the first land animals -worms, spiders, scorpions and insects - evolved as they moved on to the land.

Is it true? There are no amphibians alive today.

No. There are many different amphibians in the world today. Frogs, toads and salamanders are all amphibians.

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.

Amazing! 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.

Picture Credit : Google

Earth is millions and millions of years old. In fact, our planet is four-thousand-six-hundred-million years old. When the Earth’s age (4.6 billion years) is written as a number, it looks like this: 4,600,000,000. It’s hard for us to imagine anything so old.

Has there always been life on the Earth?

Nothing at all lived on the Earth for the first billion (1,000 million) years of the planet’s existence. The conditions were not right for life. There were no plants or animals of any kind. Earth was a dangerous place where life could not survive.

Amazing! Some of Earth’s oldest known rocks are found in Scotland. They are about 3.5 billion years old.

Has the Earth always looked the same?

These maps show how Earth’s land and sea looked in the past. To fit everything on them, Earth has been drawn as an oval. For a long time, all land was joined together in one giant mass. Over millions of years it broke up into smaller pieces. They turned into today’s continents.

Is it true? The continents are still moving.

Yes. The continents move about 4 centimetres each year - the length of your little finger. Millions of years in the future, Earth will look very different from today.