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Fossils
What is a fossil…
fos·sil
ˈfäsəl/
noun
1. the remains or impression of a
prehistoric organism preserved in
petrified form or as a mold or cast in
rock.
Types of fossils…
There are two main types of fossils; body and trace.
Body:
Trace:
 Include the
remains of
organisms that
were once living.
 Signs that
organisms were
present (ie.
footprints etc.)
Fossil origins…
Fossils can come from plants or animals.
Invertebrate
Vertebrate
 Vertebrate fossils
come from animals
who had bones.
 Invertebrate fossils
come from plants or
animals that didn’t
have bones.
Modes of preservation…
The two types of preservation are preservation w/ alteration and preservation w/o alteration.
W/O alteration
W/ alteration
 Freezing
 Mummification
 Unaltered shell remains
 Permineralization
Other types of preservation:
 Molds
(shell material is progressively removed by
leaching and it leaves a void in the rock in the
shape of the original organism)
 Casts
(void between internal and external mold is
filled with mineral matter, creating a replica of
the original organism)
(molecular exchange of substances that
were once part of an organism w/ minerals
carried in by percolating water solutions)
(chemical precipitating into pore space)
 Replacement
Carbonization
(carbonization occurs when soft tissues are
preserved as films of carbon
Radiometric and Relative Dating…
Relative dating
 Sedimentary Rock
 Layers of sediment are arranged in a sequence in order of when they happened (youngestoldest)
 Fossils are given ages based on the relative age of the layer of sediment it is found in
Radiometric dating
 Traces of radiometric elements are present in certain types of rock
 These elements can be analyzed to determine the age of these rocks and also the fossils in
them
Sedimentary Rocks…
Fossils are mostly found
in sedimentary rock
sedimentary rock
noun
1.Rock that has formed through the deposition
and solidification of sediment, especially
sediment transported by water (rivers, lakes,
and oceans), ice
(glaciers), and wind. Sedimentary rocks are
often deposited in layers, and frequently contain
fossils.
Some facts about sedimentary rocks:
 Sedimentary rocks are formed by sediment that is
deposited over time, usually as layers at the bottom
of lakes and oceans.
 This sediment can include minerals, small pieces of
plants and other organic matter.
 The sediment is compressed over a long period of
time before consolidating into solid layers of rock.
 Sedimentary rocks forms layers called strata which
can often be seen in exposed cliffs.
 Sedimentary rocks cover the majority of the Earth's
rocky surface but only make up a small percentage of
the Earth’s crust compared to metamorphic and
igneous types of rocks.
 Examples of sedimentary rocks include limestone,
sandstone, mudstone, greywacke, chalk, coal,
claystone and flint.
 Limestone forms the metamorphic rock marble when
subjected to extreme heat and pressure over time
(metamorphism).
 Sandstone forms the metamorphic rock quartzite.
 Mudstone forms the metamorphic rock slate.
 Chalk is a soft, white form of limestone.
 Flint is a hard, sedimentary form of the mineral
quartz.
http://www.sciencekids.co.nz/sciencefacts/earth/sedimentaryrocks.html
Fossil Organisms timeline…
Paleontology…
 Paleontology is the study of
fossils
 Paleontologists use
techniques from a variety of
different areas such as
biochemistry, mathematics
and engineering.
 Paleontologists have been
able to discover a lot about
the evolution of the earth,
they have discovered things
as far back in history as
3,800 million years.
 There are sub-divisions of
paleontology, some which
focus on fossil organisms and
others that focus on the
environment.
Fossil Fuels…
Fossil fuels are
fuels made from
naturally
decomposed
organisms which
can be millions
of years old
Contain large
percentages of
carbon.
Fossil fuels are a nonrenewable source
because the organisms
that create the fuels
can take millions of
years to form.
• Coal
• Petroleum
• Natural gas
“Fossil fuels are of
great importance
because they can be
burned (oxidized to
carbon dioxide and
water), producing
significant amounts of
energy per unit
weight.”
http://en.wikipedia.org/wiki/Fossil_fuel
Pictures…
Body fossil
Trace fossil
Invertebrate fossil
Vertebrate fossil
Fossil mold
Fossil cast
Bibliography
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http://www.fossilsforkids.com/
http://imnh.isu.edu/digitalatlas/geo/basics/fossil.htm
http://www.wacona.com/promote/fossils/facts.htm
http://www.bbc.co.uk/nature/fossils
http://www.mnh.si.edu/exhibits/backyarddinosaurs/questions-answers.cfm?know=a24
• http://en.wikipedia.org/wiki/Paleontology
• http://dictionary.reference.com/browse/sedimentary+rock
• http://en.wikipedia.org/wiki/Fossil_fuel