11.1 FOSSILS

what is a fossil?

any preserved trace left by an organism that lived long ago

how are human fossils found?

bones and teeth

what can affect fossil formation/degrade dead matter?

microorganisms, scavengers and the elements degrade dead matter

what are the 4 conditions for fossilisation?

1. a quick method of burial

2. the presence of hard body parts

3. an absence of decaying organisms

4. long periods of stability (left undisturbed)

is alkaline or acidic soil better for preserving fossils?

alkaline

is aerobic or anaerobic conditions better for fossil formation?

anaerobic

where are fossils usually found and why?

• at the edge of ancient lakes and river systems

• facilitates the build up of sediments

• also found in limestone caves (lime replaces minerals in bones to assist with petrification)

what are the problems with the fossil record?

1. incomplete (gaps) as conditions for fossilisation are not always present/occur at irregular periods

2. only a small proportion of fossils that exist have been discovered

3. buried too deep/are inaccessible

4. some may have been destroyed

5. rare to find fossil of entire organism (hard to make conclusions)