1. Ch. 17 Noteguide – The History of Life

2. 17.1 The Fossil Record Are scientists who study fossils
Life on Earth. It also shows how different groups of organisms have changed over time.
Incomplete, because it takes precise combinations of conditions
Extinct
Precise combinations of conditions

3. How fossils form:
Exposure to rain, heat, wind and cold breaks down existing rocks.
Minerals replace all or part of the organisms body.

4. How scientists determine the age of a fossil:
Relative dating
Rock layers
Index fossils

5. 2. How Scientists determine the age of a fossil
Radioactive dating
Half-life
Carbob-14 is taken in by living things and released slowly when they die.
To determine when the organism lived.
Carbon-14
Carbon-12

6. Geologic Time Scale
Represent evolutionary time. Places Earth rock in order by relative age.
Precambrian
Time between Precambrian + 3 eras
Paleozoic
Mesozoic
Cenozoic
Eras that are subdivided

7. 17.2 Earth’s Early History How did life on Earth Initially begin?
Heat to melt the entire globe
The most dense elements form the Earth’s core.
The early Earth was much hotter with little oxygen.

8. How did life on Earth Initially begin
27. lots of dissolved iron
28. proteinoid microspheres
29.RNA
30. nucleotides
31. a series of experiments (miller and Urey)
32.microscopic fossils
33.oxygen gas
34. oxygen for respiration

9. 35. proposes that eukaryotic cells arose from living communities formed by prokaryotic organisms

10. 36. refers to the large scale evolutionary changes that take place over long periods of time.
37. slow and steady
38. horseshoe crab
39. rapid evolution
40. hox genes