The Fossil Record

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The Fossil Record
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Section Objectives
Kinds Of Fossils Petrification Traces of
Organism Interpreting the Fossil Record Index
Fossils Fossils Clues to the Past
Boring!
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INTRO to Fossil Record
Paleontologists A Person who studies about the
earths past
Evolution The Change of living things over time
Paleontology The study of fossils.
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Kinds of Fossils
Preservation of Organisms Normally dead plants
and animals are eaten by other Animals or
Decomposed by bacteria. Only dead organisms that
are buried quickly or protected from decay can
become fossils
Mummification one way an organism can be
preserved is by mummification or Drying
Amber Many insects have been found to be
preserved in amber or hardened tree sap
Tar Beds are by thick petroleum oozing to the
earth surface
Freezing Freezing also helps preserve soil and
ice to preserve the organisms
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Petrification
Petrification organisms are usually preserved
through Petrification.
the process of turning some plant material into
stone by infiltration with water carrying
mineral particles without changing the original
shape
The process of petrification is dependent on
certain conditions.The dead wood needs  to be
protected from decay.The dead wood becomes
saturated with mineral-laden water.  The porous
nature of wood allows the movement of
water-borne particles.The water itself needs
to harbor specific and minerals necessary for
petrification.
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Traces of Organisms
Trace Fossils A remnant or trace of an organism
of a past geologic age, such as a skeleton or
leaf imprint, embedded and preserved in the
earth's crust.
Trace fossils commonly occur in rocks that do not
contain body fossils in fact, the trace fossils
may be the only evidence that organisms had once
lived in a certain area. Thus, it is important
to understand as much as we can about how traces
are made and what they mean. This is easier said
than done because the animal or plant is gone,
leaving no hard parts to study. In order to
better understand fossil traces, many
paleontologists study living organisms and their
traces.
Fossilized schist Oh Schist . They can be cut
into small sections then they can be observed
through a microscope.
A small stone found in the stomach of some
reptiles, fish, and birds that aids in digestion
by helping grind ingested food material.
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Index Fossils
Index fossils are commonly found, widely
distributed fossils that are limited in time
span. They help in dating other fossils found in
the same sedimentary layer. For example, if you
find a fossil from an unknown era near a fossil
from a known time, you can assume that the two
species were from about the same time.
Ammonites were common during the Mesozoic Era
(245 to 65 mya), They were not found after the
Cretaceous period, as they went extinct during
the K-T extinction (65 mya). Brachiopods
(mollusk-like marine animals) appeared during the
Cambrian (540 to 500 mya) some examples still
survive. Graptolites (widespread colonial marine
hemichordates) that lived from the Cambrian
period (roughly 540 to 505 million years ago) to
the early to mid-Carboniferous (360 to 320
million years ago). Nanofossils are microscopic
fossils Trilobites were common during the
Paleozoic Era (540 to 245 mya)
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Fossils Clues to the Past
Fossils also furnish scientist with important
clues to the changes in climate and
environment that occurred in the past.
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