Fossils are the preserved remains or traces of ancient organisms. They form when organisms are buried rapidly in sediment or other media, protecting them from decay. This can occur through events like mudslides, floods, or volcanic eruptions. Over time, minerals replace the organic material through permineralization or recrystallization, leaving an imprint of the original organism. The type of fossil produced depends on factors like the environment and which parts of the organism were made of hard or soft tissues. Body fossils directly preserve bones, teeth, or shells, while trace fossils preserve tracks, burrows, or other signs of biological activity. Fossils provide evidence of prehistoric life and are useful for reconstructing Earth's geological history

1. FOSSILS
• Dug up; Direct way of past study.
• Excavated from sedimentary rocks; Remains preserved
in rocks.
• The remains of creatures that lived and died and were
buried in sediments and later solidified into rocks.
• The remains of animals that lived prior to recent times at
least 10-15 thousand years.
• Remains of organisms which have acquired a
physicochemical stability with regards to their
environments.

2. FOSSILS
Fossils are the organic remains which are
naturally preserved, have physicochemical
stability with their environments and show
the exact morphology of that organic
remains.

3. Fossils are the organic remains of organisms which are
naturally preserved, have physicochemical stability with their
environment and show the exact morphology of those organic
remains.

4. FOSSILIZATION
Fossilization includes all the process
occurred during the transformation of
organic remains into fossils in sediments,
or any other comparable medium.

5. FOSSILIZATION
• Animal dies and normally eaten by scavengers or
decomposed by bacteria.
• Mud, slide, sandstorm, flood cause to bury the animal
quickly.
• Animal may be entombed by ice, tar, resin.
• Animal protects to decay and buries for myr.
• Mineral seepage, pressure and others, organisms change
(distortion, incomplete filling, complete rock conversion).
Fossilization depends on different factors:

6. FACTORS FOR FOSSILIZATION
NATURE OF ANIMALS ENVIRONMENTS
MARINE
ENVIRONMENTS
LAND
ENVIRONMENTS
SOFT
PARTS
HARD
PARTS
Floods Bogs Natural
Petroleum
Seeps
Amber Caves
and Under
Ground
Caverns
Falls of
Volcanic
Ash
Ice or
Frozen
Soil
Deserts

7. Fossil Types
Body fossils Trace fossils

8. Body Fossils
Unaltered body fossils Altered body fossils

9. Trace Fossils
Tracks, Trails, Burrows, Borings, Impressions, Molds, Casts

10. Body Fossils
Any part of the actual animal or plant (bones, teeth, shells, and
leaves). Only the hard skeleton is preserved (shell or bone), and the
soft tissue (skin, muscle, organs, etc.) rots away after death.
Unaltered Body Fossils  No change in composition
Altered Body Fossils  Complete change in composition
Trace Fossils
Geological records of biological activity of organisms preserved on
a substrate (e.g. burrows, borings footprints, muscle scars, feeding
marks, and root cavities).

11. BODY FOSSILS
Body fossil of a flat fish
TRACE FOSSILS
Chirotherium footprints in
a Triassic sandstone

12. TYPES OF FOSSILIZATION
(Mode of preservation)
Body Fossils
1. Unaltered
2. Altered
Trace Fossils

13. Fossilization in unaltered body fossils
1. Original skeletal material
2. Encrustations
3. Tar impregnation (Rancho La Brea tar pit in California)
4. Amber entombment
5. Refrigeration
6. Mummification

14. Fossilization in altered body fossils
Petrification
Permineralization Recrystallization Carbonization
Replacement

15. Fossilization in trace fossils:
• Mold i. External mold (impressions, tracks).
– ii. Internal mold or steinkerns (invertebrate shells).
• Cast
• Compression
• Borings / burrows
• Coprolite
• Gastrolith
• Gnawing

16. Other types
• Pseudo fossils
• Index fossils
• Living fossils
• Sub fossils

17. Index fossils
Define and identify geologic periods.
Pseudofossils
Inorganic objects, markings, or impressions that might be
mistaken for fossils.
Manganese dendrites on a limestone bedding plane.

18. Living fossil
Any living species which resembles species that is only known
from fossils and which has no close living relatives.
Subfossil
Remains, whose fossilization process is not complete,
A subfossil skeleton

19. Uses of fossils
• Prehistoric man utilized fossils in an attempt to ward off
evil spirits.
• Men of certain primitive culture use fossil bones as
medicine, believing that they have mysterious power of
healing wounds.
• The scientists, however, use fossils to recreate the
geological history of earth.
• The tracing of the development of plants and animals.

20. • Climatic indicators.
• Evidence of changing geographic patterns.
• Economic tools.
• Record of prehistoric life.
• Evidence of organic evolution.
• Stratigraphic indicator.
• Cultural values.

21. Harsh weather.
Impossible access to some dangerous areas.
Nature of the metabolism of Achaean organisms.
The early evolution of insects and microorganisms.