GCSE Biology - Fossils & Extinction

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*** WHAT'S COVERED ***
1. Introduction to Fossils
* Definition: Remains or traces of long-dead organisms.
* Examples: Rock skeletons, impressions, preserved organisms.
2. Importance of Studying Fossils
* Understanding extinct organisms (most life is extinct).
* Providing evidence for evolution by showing changes over time.
3. How Fossils are Formed
* Gradual replacement by minerals (mineralisation of hard parts like bone, teeth, shells).
* Casts and impressions (moulds left by organisms or footprints).
* Preservation without decay (in amber, tar pits, ice/glaciers, peat bogs due to lack of oxygen, moisture, or suitable temperature/pH).
4. The Fossil Record
* Age of the earliest fossils found.
* Why the fossil record is incomplete (early life soft-bodied, geological destruction of older fossils).
5. Extinction
* Definition: When no individuals of a species remain alive.
* Reasons for extinction: Rapid environmental changes (habitat loss, climate change), new predators (including human hunting), new diseases, competition from new species, catastrophic events (e.g., asteroid impacts).

*** CHAPTERS ***
0:00 What are Fossils?
0:24 Why Study Fossils?
1:01 Formation by Gradual Replacement by Minerals
1:35 Formation of Casts & Impressions
2:08 Formation by Preservation
2:41 The Incomplete Fossil Record
3:25 Extinction: Definition
3:34 Reasons for Extinction

*** PLAYLISTS ***






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