A fossil is any preserved remains or traces of ancient plants and animals. Fossils form when organic materials are replaced or preserved by minerals in sediment over millions of years. Conditions that promote fossilization include rapid burial to prevent decomposition, and hard body parts like bones or shells. An altered fossil is one where the original materials have been partially or completely replaced by minerals through processes like permineralization, replacement, carbonization, or mold and cast formation. Different modes of preservation can result in fossil traces that provide clues about ancient life.

1. Fossils & Altered fossil
Prepared by : Muhammad Zeeshan
Submitted to: Dr.Abdual Gaffar
Reg no: 110

2. What is a fossil?
A fossil is an impression, cast,
original material or track of
any animal or plant that is
preserved in rock after the
original organic material is
transformed or removed.

3. A fossil may be:
• an original skeleton
or shell;
• a mold or cast;
• material that has
replaced the once
living thing;
• traces such as
footprints or worm
tubes

4. What conditions promote
fossilization?
• Hard body parts
such as skeletal
bones or
exoskeletons

5. What conditions promote
fossilization?
• Rapid burial and/or
lack of oxygen

6. Altered fossil
The materials making up the fossil are partially or complexly different
from those that the animal produced when it was alive.
There are many different types of altered fossil preservation.

7. What are the modes of fossil
preservation?
•Altered
Permineralization –
pores in tissue are
filled by minerals
Replacement –
replacement of
tissue with
minerals

8. What are the modes of fossil
preservation for body fossils?
•Altered
Carbonization – tissue
material is
decomposed or
reduced to a film of
carbon

9. • Mold – reproduction
of the inside or
outside surface of a
living thing
• Cast – duplicate of
the original
organism; usually
formed by
replacement of
inside of living thing

10. Thank you!