Fossils!
What is a fossil?
Fossils are any
evidence such as
the remains,
imprints, or traces
of once living
organisms (plants
& animals)
preserved in rocks.
Fossils provide clues to past
geologic events and evolution of
life forms.
PALEONTOLOGIST
A Scientist that studies
fossils to learn about
Earth’s past.
Paleontologists arrange
fossils in the order in
which they lived, from
earliest to latest. All the
information gathered
about past life is called
the fossil record.
What are the different kinds of
fossils?
 Original
Remains
 Petrified Remains (wood)
 Carbon Films
 Trace Fossils
 Molds and Casts
What is an
Original Remain?
Original Remains: Fossils that are the
actual bodies or body parts of an
organism.

Some processes preserve the
remains of the organisms with little
or no change.
A. Mummification (drying)Because most bacteria cannot
survive without water, the
mummified organism does not
decay.
B. Amber- Many insects have
been found preserved in
hardened resin or sap called
amber.
C. Tar - Formed by thick
petroleum oozing to the Earth’s
surface. The tar beds are often
covered with water. Animals
that came to drink the water
became trapped in the tar and
were preserved.
D. IceMost bacteria cannot survive
freezing temperatures, organisms
buried in frozen soil or ice do not
decay. The frozen remains of
relatives of elephants called woolly
mammoths have been found in
very cold regions. Freezing has
preserved even mammoth’s hair &
skin.
How do organisms become
petrified (mineralized)?
Petrified organisms are fossils in
which minerals replace all or part of
an organism, changing the
organism into stone. The most
common organism that
becomes petrified is wood.
Describe a Carbon Film
A thin film of carbon residue that
forms an outline of the original
organism leaving behind fine,
delicate details.
When sediment buries an organism, the
weight of the sediment squeezes almost
all of the decaying organism away.
Eventually, only a thin film of carbon
remains.
Hold up a fossil and tilt it back and forth in the light. If it has a shiny, black
appearance, then its a “carbon film” fossil.
Trace Fossils
Fossils that contain no part
of an organism, but show
evidence of their
existence.
A. Imprints
When
an outline of an
organism is pressed into soft
sediment (mud) and the
sediment turns into stone
preserving the outline, such
as the footprint of an animal
or the outline of a leaf.
B. Coprolites- Fossilized waste
material
a.k.a poop!
Casts and Molds
Often organisms are buried by sediments.
If the sediments turn into rock and the
organisms decay, empty cavities are left
behind. These empty cavities are
called molds.
Sometimes the molds are filled with sand
and mud that later hardens forming a
replica of the original organism. These
replicas are called casts.
A cast is the opposite of a mold.
The End