1. Fossils

2. What are Fossils?
• Fossils are the remains or marks of plants
and animals that lived a very long time
ago. They are usually found in rock and
stone.
• Fossils are important because they tell us
a story about things that lived on the earth
before us.

3. What Things Become Fossils?
• Animals and plants become fossils.
• So do nests, eggs, footprints and even
animal droppings!

4. How are Fossils Made?
• Fossils are made from the hard parts of
plants and animals, such as:
- bark, seed cases, bones and teeth.
• These parts do not easily rot away after
plants and animals die.
• Fossils take millions of
years to form.

5. Turning to Stone
• For example:
- A starfish dies.
- The soft parts of its body rot away quickly.
- The harder parts slowly get covered by mud.
- After millions of years, the starfish is deep in the ground.
- The mud around it is crushed by the land on top and
turned to stone.
- So are the remains of the starfish.
- Millions of years later, the stone gets worn away and the
fossil can be seen.

6. How Fossils are Formed

7. From the Sea
• The first creatures on the earth lived in the
sea.
• Some sea creatures made good fossils
because they had hard shells and hard
bones.
Trilobite Fossil
Horseshoe Crab Fossil
Fish Fossil

8. Plants
• At first, there were only Pine Cone Fossil
living things in the sea.
• Slowly, over millions of
years, plants began to grow
on the land.
• Some of these plants have
left fossils in the rock.

9. Animals
• Animal fossils are often bones that have been turned to rock. Sometimes
part of the flesh is preserved, but most of the time only skeletons remain.
• Because of this, it is more difficult to find fossils of invertebrates.
(Invertebrates are animals that don’t have bones.)
• We have discovered several types of animal fossils: bones, skin, teeth,
claws, eggs, nests, muscles, and organs.
• We have also found lots of fossils of footprints, which tell us how much
animals and dinosaurs weighed and how they might have walked.

10. When Did They Live?
• First Fish  570 million years ago.
• First plants on land  440 million
years ago.
• First insects and amphibians  400
million years ago.
• First reptiles  360 million years ago.
• First dinosaurs  245 million years
ago.
• First birds  210 million years ago.