Fossils (AQA GCSE Biology): Flashcards
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What are fossils?
What are fossils?
Preserved remains of organisms in rocks from millions of years ago
What does the fossil record provide evidence for?
What does the fossil record provide evidence for?
Evolution by natural selection
Fossil formation: traces
Fossil formation: traces
Footprints & burrows preserved in rock
Fossil formation: hard parts
Fossil formation: hard parts
Replaced by minerals (mineralisation)
Fossil formation: soft tissues
Fossil formation: soft tissues
Don't decay when oxygen/water are absent or temperature is low
What conditions does decay need?
What conditions does decay need?
Oxygen and water
Why is the fossil record incomplete?
Why is the fossil record incomplete?
Soft bodies, geological activity, decay, eaten
What is extinction?
What is extinction?
No living individuals of a species left on Earth
Extinction: environmental change
Extinction: environmental change
Organisms can't adapt quickly enough to major changes
Extinction: catastrophic events
Extinction: catastrophic events
Asteroid collisions, massive volcanic eruptions
Extinction: new threats
Extinction: new threats
New diseases, predators, or competitors
Why vertebrates fossilise better
Why vertebrates fossilise better
Bones & teeth are hard, more likely preserved