FOSSILS

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FOSSILS

• - any naturally preserved evidence of life
• - rock fossils, petrifaction, amber fossils,
  mummification, frozen fossils, fossils in tar.

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Rock Fossils
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Petrified Wood
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Amber Fossils
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Mummification
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Frozen Fossils
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Tar Pit Fossils
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Trace Fossils

• preserved evidence of an animals activity
  (footprints, coprolites)

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Trace Fossils
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Coprolites
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Mold

• a cavity where an organism was buried, but
  decayed

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Mold
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Cast

• when a mold gets filled in with sediment and
  becomes a fossil

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Cast
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Absolute Dating

• how to establish the actual age of an object.

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Radiometric Dating

• by knowing the rate of radioactive decay, you
  can figure out the age of a rock. (Uranium-lead,
  potassium-argon, carbon-14)

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Radiometric dating
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Carbon 14 Dating
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Index Fossils

• if they know when one of the organism lived,
  can date the layer it was found in to date
  unknown fossils.

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Index Fossils
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The Geologic Time Scale

• - divides Earths 4.6 billion year history into
  distinct time intervals.
• - the divisions are eons, era, periods and
  epochs.

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Geologic Time Scale
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Paleozoic Era Old Life

• - started with no land organisms, then came
  plants, amphibians and insects. At the end came
  a mass extinction when 90 of all species
  perished.
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• 1. Grand Canyon formed
• 2. Trilobites in sea, land plants
• 3. Coral reefs, insects and fish

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Paleozoic Era
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Mesozoic Era Middle Life

• - the age of reptiles, when dinosaurs existed,
  birds and small mammals began to evolve.
• - At the end, 50 of the species became extinct,
  including dinos.
• 4. Pterosaurs appear, conifers develop
• 5. Reptiles develop
• 6. Dinosaurs abundant

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Mesozoic Era
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Cenozoic Era recent life

• era we live in, the age of mammals, many now
  extinct
• 7. Flowering plants and mammals appear
• 8. Rhinos and birds appear
• 9. Mammoths and humans appear.
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Cenozoic Era