Evolution

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Evolution

• Fossil Record as Fair Test(Part II)

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Theory of Evolution

• All life on Earth descended from a common
  ancestor
• Life originated as a simple form, and became more
  diverse and complex over time

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Fossil Record

• Represents 4,000,000,000 year long record of
  the natural history of our planet

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I. Evidence in the Fossil Record

• Evidence that life changed through timesimple ?
  complex
• Evidence of change in one type of animal
  through the years
• Transition species evidence of hybrids
  between two types
• 99 of all life which has ever existed is now
  extinct

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What does the fossil record tell us?

• Life originated in a simple form and become more
  complex and diverse with time.
• Example 1
• Example 2
• Example 3

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What does the fossil record tell us?

• 2) Organisms have changed over time
• Changes within a type of animal
• Sea Urchins (video)
• Horse (video -can you describe?)

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Horse Transitions

• Each branch tip on the tree of horse evolution
  indicates a different genus, though the feet of
  only a few genera are illustrated to show the
  reduction of toes through time.

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What does the fossil record tell us?

• 2) One problem with the theory of evolution is
  the conspicuous lack of transition fossils
• Is this true?

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Archaeopteryx
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Other Transition Fossils

• Transitions from one type into another
• Skulls reptile/mammal hybrids (Why is this
  significant?)
• Whale Transition Fossils (See pbs evolution
  series cool show!)

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Fossil RecordEvolution of Mammals

• Skulls showing the changes in the jaw
  articulation and the ear region in the evolution
  from reptile to mammal.

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Whale Transitions
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Whale Transitional Forms
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And, (Drum roll, please.)

• Published April 6, 2006
• See http//tiktaalik.uchicago.edu/

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Fossil Called Missing Link From Sea to Land
Animals
Model of Tiktaalik roseae, a 375 million year old
fish with many amphibian-like features and
foot-like bone structure in its fins that could
have helped it pull itself through shallow water
and even out of the water for brief periods
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What does the fossil record tell us?

• 3) 99 of all organisms which have ever existed
  are now extinct!
• (The life we observe today has not been the life
  through the ages!)