Evolution: A Remodeling process

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Evolution A Remodeling process

• Section 15.2

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Refinement of Existing Adaptations

• Any living organism may have many adaptations.
• A complex structure may have evolved from simpler
  structures.
• Ex Camera like eye of mammals has evolved from
  simpler eye types

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Adaptation of Existing Structures to New Functions

• Flippers of Penguins? modified wings

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Development

• Feet in various salamanders
• Salamanders ? vertebrates closely related to
  frogs, live in land or water, but some live in
  trees
• Tree dwelling ones have feet adapted to climbing

Ground Dwelling
Tree Dwelling w/ more webbing
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Fossil records

• Section 15.3

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• Formation of Fossils
• Fossil Records and the Geologic Time Scale
• Dating Fossils
• Continental Drift
• Mass Extinction

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Fossil Records and the Geologic Time Scale

• Most Recent Layers Top
• Oldest Layers Bottom

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Geologic Time Scale

• Distinct Ages in Earths History
• Precambrian
• Paleozoic
• Mesozoic
• Cenozoic
• See fig 15-18 p337

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Dating Fossils

• Relative Dating
• Absolute Dating
• Radioactive Dating

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Relative Dating

• Determines the Order in which events occurred
• Not Actual Age

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Absolute Dating

• Determines how long ago an event occurred Actual
  Age

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Radioactive Dating

• Based on measurement of certain radioactive
  isotopes.
• Used to determine the absolute ages of rocks and
  fossils
• Measured in Half-Life

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Half-Life

• Time required for a radioisotope to lose ½ of its
  radioactivity.
• Ex Carbon-14 ½ life 5730 yrs. decays into
  Nitrogen-14

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• Carbon-14 is produced in the atmosphere fairly
  constant rate
• 14C is constant in all living things. When an
  organism dies, it no longer picks up 14C.
• By comparing the activity of a sample with the
  activity of living tissue? time an organism has
  been dead

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Continental Drift

• Land masses on different plates change positions
  as a result of movement

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Mass Extinction

• Long periods of relative stability broken by
  comparatively brief episodes of species loss
• 5 or 6 over the last million years