This document provides an overview of paleontology and the different types of fossils. It discusses how fossils are formed when organisms are buried and their remains become preserved in sediment that later hardens into rock. The main types of fossils discussed are petrified fossils in which minerals replace the organism's remains, molds and casts which copy the organism's shape, carbon films which leave a carbon outline, and trace fossils which are marks left by an organism's movements. Fossils provide clues about past life and environments on Earth. Paleontologists study fossils to understand how life has changed over time.

2. Paleontology—The Study of Past Life
• The history of the Earth would be incomplete
without knowledge of the organisms that have
inhabited our planet and the conditions under
which they lived.
• The science involved with the study of past life
is called paleontology.
• Paleontologists study fossils, which are the
remains of organisms preserved by geologic
processes.

3. Fossil
 Preserved remains of a past organism

4. FORMATION OF FOSSILS
 Fossilized- the process of becoming a fossil.
 Fossils are evidence of past life, preserved in
rock.
 Most fossils form when living things die and
are buried by sediments.
 The sediments slowly harden into rock and
preserve the shapes of the organisms.

5. The Fossil Record and life
 The fossil record is the complete body of
fossils that shows how species and ecosystems
change over time.

6. What do fossils tell us?
 Fossils provide evidence of how
life has changed over time.
 Fossils help scientists infer how
Earth’s surface has changed.
 Fossils are clues to what past
environments were like.

8. Types of fossils
 Petrified fossils
 Molds and casts
 Carbon films
 Trace fossils
 Index fossils
 Preserved remains

9. Petrified Fossils
 Fossils in which minerals
replace all or part of an
organism.
 How does this happen?
 Water rich in dissolved minerals
seeped into spaces, then
evaporated, leaving the hardened
minerals behind.
 Example – petrified wood

10. Molds and casts
 Most common type of fossil.
 Both copy the shape of the organism.
 A mold is a hollow area of sediment in the shape of
the organism.
 A cast is a copy of the shape of an organism.
Cast fossil
Mold fossil
Consider this:
Mold and cast
fossils can be
compared to
a cake pan.
The pan is the
mold, and the
cake is the
cast.

11. Carbonization-Carbon Films
 Leaves extremely thin coating of carbon film outline on
rock.
 How does this happen?
All organisms are made of carbon.
When they are buried,
the materials that make up
the organism evaporates.
These gases escape
leaving carbon behind.

12.  Trace fossils are a fossilized mark that is formed in soft
sediment by the movement or actions of an animal.
 Examples
 A footprint provides clues about the size and
behavior, the speed, how many legs it walked on,
lived alone or with others.
 A trail or burrow can give clues about the size and
shape of the organism, where it lived, and how it
obtained food.
Trace Fossils

13. Index Fossils
 An index fossil is a fossil found in a narrow
time range but widely distributed around the
earth; used to date rock layers.
 Example
 Trilobite: a marine organism that has become a fossil.
 Ammonite

16. Preserved remains
 Preservation of
remains with
little or no
change.
Bog
Mummies

17. Preserved remains
 Tar
 The sticky oil that
seeps from
Earth’s surface.
Tar soaks into the
organisms bones,
preserving the
bones from decay.

18. Preserved remains
 Amber
 The hardened
resin, or sap, of
trees. The
amber seals the
organism from
the air
protecting it
from decay.

19. Preserved remains
Ice
 Ice Fossils are actual flesh remains of
the organism. They become
trapped in ice and
remain frozen until
they thaw. A good example
of an ice fossil is a
Woolly Mammoth,
which are often
found in the Arctic.

20. NOW- Answer the following questions in
the margins below the notes.
Observe the fossil at the left.
A. What does it look like?
B. what type of fossil is it?
These fossils are believed to be found in the
Sahara Desert;
C. What might you infer about how they got
there?
Begin working on your Fossil stations.