1. (7th) Chapter 8-5 Cornell Notes

2. Chapter 8-5 Key Questions
Why is the geologic time scale used to show Earth’s history?
What were early Precambrian organisms like?
What were the major events of the Paleozoic, Mesozoic, and Cenozoic eras?

3. Chapter 8-5 Key Terms geologic time scale- era- period- invertebrate-
amphibian-
reptile-
mass extinction-
mammal-

4. Chapter 8-5 Paragraph 1
geologic time scale: record of geologic events + life forms in Earth’s history.

5. Chapter 8-5 Paragraph 2 starts with Precambrian Time;
then divided into eras which contain periods.
Chapter Paragraph 2

6. Chapter 8-5 Paragraph 3 earliest life forms ~ 3.5 billion years old;
probably bacteria-like.

7. Chapter 8-5 Paragraph 4 Cambrian explosion;
Paleozoic Era: many kinds of organisms developed;
like invertebrates or without backbones,
like jawless fishes = 1st vertebrates;
Devonian Period: animals invade land;
amphibians 1st land animals;
Carboniferous Period: small reptiles develop.

8. Permian Period (end of Paleozoic Era) mass extinction (+90%);
aka Permian extinction;
affected land and sea animals;
possible cause: climate change from continental drift;
Pangaea forms during Permian Period.
Chapter Paragraph 5

9. Chapter 8-5 Paragraph 6 Mesozoic Era: aka Age of Reptiles;
1st dinosaurs appear;
and 1st mammals.

10. Chapter Paragraph 7
Cretaceous Period: (end of Mesozoic Era) another mass extinction;
probably due to asteroid collision.

11. Chapter Paragraph 8
dinosaur extinction opened pathway for mammals to develop;
Earth’s climate cooled causing series of ice ages to develop;
beginning new era called Cenozoic with the Quartenary Period.