1 / 12

Evolution- Change in life forms over time

Evolution- Change in life forms over time. Why do things change? How do they change?. Estimated age of earth-4.6 Billion years 4 geologic eras Precambrian Paleozoic Mesozoic Cenozoic episodes of mass extinction separates eras. At the beginning

levia
Download Presentation

Evolution- Change in life forms over time

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Evolution- Change in life forms over time Why do things change? How do they change?

  2. Estimated age of earth-4.6 Billion years 4 geologic eras • Precambrian • Paleozoic • Mesozoic • Cenozoic episodes of mass extinction separates eras

  3. At the beginning • Hot, lots of volcanic activity, no free oxygen, but lots of water vapor. • 3.9 Billion years ago, oceans formed • 3.5 BYA first fossil evidence of life- photosynthetic bacteria

  4. The history of earth is written in the rocks. • Fossil: evidence of existence preserved in rock • Structure indicates function Oldest fossils found are 3.5 billion years old and are microscopic photosynthetic bacteria

  5. Analyzing the fossil record • Life was incredible diverse • Size, structure, function • Episodes of mass extinction • Episodes of evolutionary explosions

  6. Fossil Formation • Organism dies • Covered with mud, sand- no decay Compression over time = sedimentary rock and fossil Where might fossils be forming today?

  7. Formation of fossils • Casts- minerals fill in • Mold- leaves an empty space • Amber-preserved or frozen • Trace or carbon imprint

  8. Determining the age of a fossil: 2 ways • Relative dating • Absolute dating

  9. 2. Absolute dating • More accurate than relative dating • Uses radioactive decay of isotopes • Isotopesare radioactive natural variations of elements

  10. Examples of Isotopes T1/2 in years • C-14 decays to N14 5730 years • Uranium 235 to Lead 207 700 million • Potassium 40 to Argon 40 1.3 billion • Half life is the time it takes for half (50%) of the isotope to change into new form.

  11. “Parent” compound is C14 • “Daughter “ compound is N14 • T1/2 is 5730 years • Start with 12.5g of C14 and 187.5 g of N14. How old is your fossil?

  12. Carbon 14 is used for fossils < 50,000 years old • Potassium-40 for older specimens

More Related