Fossils Flashcards
1
Q
What are fossils
A
Fossils are the remains of organisms that lived a long time ago and were conserved, especially in sedimentary rocks
2
Q
How are fossils formed
A
- The organism dies where it can be covered with sediment (bottom of sea/river)
- Where anaerobic conditions occur, making decomposition possible
- Covering with sediment must be fast and usually occurs on the bottom of seas or lakes
- Any hard parts of the organisms can slowly be replaced by minerals
- Or dissolve leaving only an impression of the natural form
- Can leave a mould
- Whole organisms can be intact i.e. insects trapped in amber
3
Q
Types of fossils
A
- Body fossils: refer to the fossilisation of organisms or body parts
- Form fossils: are formed when the sediment hardens around the organism, but the organism itself is dissolved by acid in the water
- Moulds: form when the cavity of a form fossil is filled with hardened materials
- Trace fossils: refer to marks made by an animal as it walked over sediment that hardened at a later stage
- Unchanged fossils: include insects in amber or frozen fossils
4
Q
The fossil record is not very complete:
A
Only 0.1% of all organisms that ever lived, formed fossils, the test either decomposed or were eaten
5
Q
Archaeopteryx
A
- Transitional fossil between reptiles and birds
- Called the “missing link” or “Old Wing”
- Had wings and feathers but when the wings are disregarded it is clearly a reptile with a long tail, dinosaur skull, teeth and claws
- “warm-blooded”
6
Q
South Africa is the only are in the world with:
A
- The oldest proof of life on earth
- The oldest multicellular organisms
- The oldest ancestors of the dinosaurs
- The most complete record of the origin of mammals
- An incredible record of the origin of mankind
7
Q
Why are fossils important
A
We can study:
- trends in biodiversity
- evolutionary relationships
- forming of sediments
- explore and find economically important records
