Fossil formation and speciation Flashcards
1
Q
What are fossils?
A
Fossils are an imprint of a once living organism
The organic part has been replaced by rock minerals
Formed over thousands of years
2
Q
What is essential for preservation / fossilisation?
A
NO OXYGEN
3
Q
How are fossils formed?
A
- Animal dies
- Layers of sediment are deposited over the body
- There is a lack of oxygen and so the microbes slowly decompose the body over hundreds of years
- The animal leaves an imprint, the natural gases are replaced with rock minerals
- yo fossil
4
Q
What reasons what affect the fossil record?
A
- Earth movements eg Earth quakes and volcano formation
- Incorrect conditions for fossil formation
- Some fossils have not yet been found
5
Q
How do species evolve from one common ancestor?
A
Variation in genes
One animal born with gene mutation, they are able to survive, pass on this mutated gene, entire species have this gene
In other areas, this gene is not beneficial and they do not evolve it -> therefore leading to two new species
