1.5 Animals of the past

• Biologie
• Middelbare school
• vwo
• Leerjaar 1

1.5 Animals from the past

Learning objective

You will learn how to investigate animals that lived in prehistoric times, how fossils are formed and how to determine the age of a fossil.

How do we know what lived in the past?

Some animals are extinct, such as dinosaurs.

We can find out what they looked like from fossils (remains of plants or animals)

How do we know what lived in the past?

Sometimes whole organisms, sometimes just a small part

Fossil research: paleontology

A scientist who investigates fossils: paleontologist

Reconstruction: trying to rebuild an organism as it really was by observing the fossils

How are fossils formed?

Dead animals and plants

Fossils must be buried quickly

River delta -> river flows into the sea

Desert

What are fossils?

1. Animal remains
2. Remains of plants
3. Remains of plants and animals
4. Human remains

How are fossils formed?

• Dead animals sank to the bottom of the sea. The soft parts decomposed.
  
• The hard parts were covered by layers of sediment.
• The pressure and heat of the earth made the soil layers as hard as stone. This is called petrifaction.

How are fossils formed?

Slowly the sea became land.

Wind and water caused erosion: pieces of soil wore away

The fossils 'emerged' again

True or false? Fossils can only be found underwater

1. True
2. False

How do you determine the age of a fossil?

If you know in which layer of stone a fossil is located, you can determine its approximate age.

Oldest layers are on the bottom, newest layers are on top

Index fossils

Fossils that are used to determine the age of a stone layer.

• come from organisms that only have lived a short period of time
• were very common at that time
• are distributed in a wide area
• easy to recognise

ammonite (250-65 million years ago)

How do you determine the age of a fossil?

Substances change over time

Carbon exists in living and dead things, and it changes at known rates

By looking at that substance, scientists know how long ago the organism ended up in the soil

Homework

Choose from:

- Create a summary of 1.5

- Create a mind map of 1.5

- Do assignments from 1.5 (3-11)