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EARTH
SCIENCE
36
Source: The Science Spot
3. What is the "Cambrian Explosion of Life"?
A: When the dinosaurs became extinct
B: When all modern phyla started to appear
C: When plants burst into bloom
D: When the first land mammals appear
4. If we compare geologic time to your life
from when you were born to when you
started high school, the first multicellular
organism wouldn't evolve until you were
_________.
A: 20 years old
B: 12 years old
C: 50 years old
D: 5 years old
4 Geologic Time Scale
continued
