EVOLUTION The History of Life Lecture 11

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EVOLUTIONThe History of LifeLecture 11

• Southern Boone County HS
• College Biology
• Mr. Palmer

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Early History of the Earth

• About 4.6 BYA Earth forms
• Very Hot
• Many meteorites colliding with earth
• Volcanoes
• Radioactive material
• Little Oxygen
• Lots of Water, Carbon Dioxide, and Nitrogen

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Early History of the Earth

• 3.9 BYA-earth cools and water condenses
• 3.5 BYA first life forms in oceans

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Early History of the Earth

• Fossils are clues to the past
• Fossil-any evidence of an organism that lived
  long ago
• Todays millions of species are a small fraction
  of all the species that have ever lived
• Paleontologist-person who studies ancient life

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Early History of the Earth

• Fossils can tell a lot about organisms
• Teeth-what it ate
• Bones-overall size
• Leaves-climate
• Coprolites-what it ate

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Early History of the Earth

• Most fossils are found in sedimentary rocks when
  they are buried by sand, mud, or clay
• Some fossils get caught in tree sap-Insects in
  amber (Jurassic Park)
• Some fossils get buried by ash from volcanoes
• Usually not in metamorphic or igneous rocks

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Early History of the Earth

• Relative Dating-used to tell relative ages-A is
  older than B B is younger than D, etc.
• Oldest rock are usually on the bottom youngest
  rocks are usually on top
• A process called folding can change the order

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Early History of the Earth

• Radiometric Dating-using radioactive isotopes to
  determine the exact age of a fossil
• Half Life is how long it takes for ½ of a
  radioactive element to decay
• Carbon-14 can date materials to about 50,000 YO
• Potassium-40 can date materials to billions of
  years old

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Early History of the Earth

• Geologic Time Scale-the chronology of the earths
  history
• There are 4 eras
• Precambrian
• Paleozoic
• Mesozoic
• Cenozoic

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Early History of the Earth

• Eras are divided into periods
• Divisions are characterized by the organisms that
  lived in them
• There were apparently times when many organisms
  died off-Mass Extinctions

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Early History of the Earth

• Life in the Precambrian
• Oldest fossils are 3.5 BYO found in Australia
• Simple bacteria
• Stromatolites
• Simple prokaryotic cells
• 1.8 BYA eukaryotic cells appear
• Sponges and jellyfish 544 MYA

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Early History of the Earth

• Life in the Paleozoic
• Lasted until 245 MYA
• Many simple plants and animals
• Worms, starfish, arthropods
• Simple fish, ferns, seed plants
• First amphibians come onto land
• At the end of the Paleozoic era there was a mass
  extinction that killed about 90 of marine
  species and 70 of land species

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Early History of the Earth

• Life in the Mesozoic
• Triassic Period
• Began about 245 MYA
• Fossil mammals-small and mouse-like
• Dinosaurs, reptiles

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Early History of the Earth

• Life in the Mesozoic
• Jurassic period
• Began 208 MYA
• Age of dinosaurs-T rex, Velociraptor,
• Modern birds appear
• Giant Mass Extinction

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Early History of the Earth

• Life in the Mesozoic
• Cretaceous period
• Began 144 MYA
• Many new mammals
• Flowering plants
• Giant Mass Extinction 66 MYA
• Killed dinosaurs and 66 of all species
• Meteorite that hit gulf of Mexico off of East
  coast of Mexico filled atmosphere with a thick
  cloud cooling earth and causing the mass
  extinction

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Early History of the Earth

• Life in the Mesozoic
• Continental Drift-plate tectonics

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Early History of the Earth

• Life in the Cenozoic
• Began 66 MYA
• Many Mammals
• First primates appeared 30 MYA
• Modern humans appeared 200,000 YA

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Early History of the EarthWrap up

1. How old is the earth?
2. Name three gases that were on early earth?
3. List three sources of heat on early earth.
4. How long ago did water condense on earth?
5. How long ago did the first life appear on earth?
6. What is a fossil?
7. What do you call a person who studies fossils?
8. Give four examples of how a fossil or part of a
   fossil can tell you about the organism.

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Early History of the EarthWrap up

• 9. Where did the DNA for the Jurassic Park
  dinosaurs come from?
• 10. What is radiometric dating?
• 11. What is the chronology of the earths history
  called?
• 12. List the four eras.
• 13. How are eras broken down?
• 14. What is a mass extinction?

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Early History of the EarthWrap up

• 15. What is a mass extinction?
• 16. What kind of organisms are found in the
  Precambrian? Samples?
• 17. What kind of animals are found the the
  Paleozoic?
• 18. When did the Paleozoic begin and end?
• 19. What kind of animals were found in the
  Cenozoic Period?
• 20. When did humans first appear?
• 21. When were two mass extinctions?