Transcript Fossils - Fulton County Schools

Evolution:
The Science behind the theory
•Geological time
•Fossils
•Darwin & Natural Selection
•Species changing over time
•Anatomical & Embryological evidence
•Speciation
Summary of Evolution of Life
Chemical Evolution
(1 billion years)
Formation
of the
earth’s
early
crust and
atmosphere
Small
organic
molecules
form in
the seas
Large
organic
molecules
(biopolymers)
form in
the seas
First
protocells
form in
the seas
Biological Evolution
(3.7 billion years)
Single-cell
prokaryotes
form in
the seas
Single-cell
eukaryotes
form in
the seas
Variety of
multicellular
organisms
form, first
in the seas
and later
on land
How do we know
about the past?
Fossils
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.
A fossil may be:
 an original
skeleton or shell;
 a mold or cast;
 traces such as
footprints or
worm tubes
Material that has replaced the
once living thing
Types of Fossils
Body fossils –
actual parts of an organism
bones, shells, leaf imprints
Types of Fossils
Trace fossils –
evidence of life having been there
tracks, burrows, casts
Trace Fossils
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
Trace Fossils
Burrows or borings –
Spaces dug out by living
things & preserved as is
or filled in
Tracks –
impressions of passage
of living things
Trace Fossils
Imprint –
Thin objects such
as a leaf that falls
onto sediment &
leaves an imprint
then the sediment
hardens into rock
Petrified Fossils
Minerals penetrate
& replace the hard
parts of an organism
producing a copy of them
Amber & Ice
An entire organism was
quickly trapped in ice or
tree sap that hardens
into amber
Where are fossils
found?
Sedimentary
Rock
Why sedimentary
rock?
What conditions
promote fossilization?
Hard body parts
such as skeletal
bones or
exoskeletons
Rapid burial and/or
lack of Oxygen
Unaltered
- insects or
plant parts trapped in amber or
ice ; original unaltered material
from the living organism
Replacement
– the hard
parts of an organism dissolve and
are replaced by other minerals
Petrification
– rock-like
minerals seep in slowly and replace
the original organic tissues
Authigenic- molds or
casts of organisms tissue material
is decomposed or of markings left
behind by an orgasnism
Putting it all together
Examples of Fossils . . .
Sporadoceras
Nautilus
Orthoceras
Squid
Trilobites
Lobster
Fossil
Fish
Dinosaur Bones