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17.1
Fossils
Paleontologists- study fossils
Fossil Record
evidence for hist. of life and how
species have changed over time
Extinct- some species have died out
Fossils
Fossils Form
buried in rock (sand/silt/clay)
hardens around organism
preserves an imprint of specimin
dating
Relative dating
age of a fossil is compared to other
fossils in other layers of rocks
Index fossils
easily recognized organism that only
existed for a short period of time
dating
Radioactive dating
C-14 dating
fossils younger than 60,000 years
Potassium-40 dating
fossils billions of years old
Time
Geological Time
represents evolutionary time line of
earth
Time is divided into eras
Eras is divided into periods