Download Fossil - Biology

Chapter 14
Evidence for Evolution
What are Evidences for Evolution?
What are the Evidences for
Evolution?
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1 Fossils
2 Homologous Structures
3 Vestigial Structures
4 Embryology
5 Macromolecules
What is a Fossil?
• Fossil – Evidence of
a life long past.
– Mineralized remains of
plant or animal life
– Trapped in solid
material and frozen in
time
What type of rock are fossils
commonly found in?
• Igneous – volcanic rock
• Sedimentary – sand and dirt become
cemented (bottom or oceans and rivers).
Most common rock where fossils are
found.
• Metamorphic – igneous or sedimentary
rocks that have re-crystallized due to high
temperature and pressure.
What are the main types of fossils?
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1. Trace Fossils
2. Molds and Casts
3. Replacement
4. Petrified or Permineralized
5. Amber
6. Original Material
Trace Fossil
• Any indirect evidence
left by an organism.
Footprints, burrows,
and fossilized feces
are trace fossils.
Molds and Casts
• Mold – imprint of the
organism
– Kindergarten hand
imprint
• Cast – A mold that
has been filled with
sediment.
What are the main types of fossils?
• Replacement –
Original specimen is
replaced by mineral
crystals that leave a
detailed replica.
Petrified or Permineralized
• Empty pores are filled
in by minerals, such
as petrified wood
What are the main types of fossils?
• Preservation – entire
organism remains
intact because it is
trapped in tree sap
which hardens into
amber.
Original Material
• Created by
mummification or
freezing and
preserves the original
organism intact.
Law of Superposition
• Relative dating is a
technique used to
compare the age of
one specimen to
another.
• The Law of
Superposition states
that younger rocks
are always found on
top of older rocks.
Radiometric Dating
• Radiometric dating allows scientists to accurately date
the age of fossils by measuring the amount of decay of a
radioisotope.
• Knowing the half life of the isotope is required.
• Example: Carbon 14
How are fossils useful?
• Allow us to detect Mass Extinctions
– More fossils in strata of earth from dying off of
organisms.
– Major extinction of dinosaurs 65 mya
What caused mass extinctions?
• 1. Massive volcanic eruption
• 2. Meteorite Impact
• Either one would have created enough
ash and sulfur to cool the earth and block
the sun.
– Remember the sun is the ultimate source of
life on Earth.
Homework
• Page 400
– 14.1 Assessment questions 1-3
– Answer in complete sentences
• Summary
– Look through your notes and section 14.1.
– Choose the main concepts
– Write a two paragraph summary of the
concepts presented in your own words.