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