AQA GCSE Fossils(Biology) - Science Worksheets

AQA GCSE Fossils (Biology)

Fossils

Fossils are the preserved remains or traces of organisms that lived millions of years ago, usually found in rocks.

They provide important evidence for how life on Earth has changed over time.

How are fossils formed

1. Fossils from preserved remains

Some fossils form when decay does not fully happen.

This can occur when:

There is no oxygen
The temperature is too low
There are no decomposers (like bacteria)

Example: insects trapped in amber

2. Fossils formed by mineral replacement

When an organism dies, the soft parts decay. Hard parts like bones or shells remain. Over time, minerals replace the original material. This creates a rock-like copy of the organism.

3. Trace fossils

These are not parts of the organism itself, but evidence of their activity:

Footprints
Burrows
Root traces

Why is the fossil record incomplete?

The fossil record does not show all organisms that ever lived.

Reasons:

Many early organisms were soft-bodied so they decayed completely.

Geological processes (heat, pressure, erosion) destroy fossils.

Fossilisation is rare and needs specific conditions.

This means scientists are not completely certain how life began.

What can fossils tell us?

Fossils help scientists:

Understand how organisms have changed over time
Identify extinct species
Study evolution

They show that:

Some organisms have changed a lot
Some have changed very little

Interpreting data

You should be able to:

Read graphs showing fossil discoveries over time
Interpret evolutionary trees
Analyse patterns in fossil records

How scientific ideas developed

Early scientists had limited fossil evidence
As more fossils were discovered, ideas about evolution improved
New technology (e.g. dating methods) made conclusions more accurate

Simple data interpretation graph

Practice Questions