1. History of Earth

2. Slide 38 - Geologic Time Scale Sequence of events from Earth’s birth to present-day (now). Each Era begins after a mass extinction of species.  Four main eras: 1. Precambrian: Earth’s Birth and the life form known as Cyanobacteria evolved. 2. Paleozoic: Plants evolved. 3. Mesozoic: Dinosaurs evolved. Dinosaurs along with 90% of the other organisms living on planet Earth became extinct when a meteor hit Earth. The impact caused particles to fly in the air and block the sun, resulting in the ice age. 4. Cenozoic: (Present – day) – Humans evolved.

3. Slide 39 - When Earth was born No life existed. SurfaceSo hot all of Earth was melted rock! AtmosphereNo O2 because no plants existed yet! Only gasses from outgassing (Volcanoes erupting). OceansNo liquid water. Too hot! Everything was Water vapor.

4. Slide 40 -Where did O2 come from? Photosynthesis from plants!

5. Slide 41 - Rocks Where fossils are found!

6. Slide 42 - Fossil Anything left from a living organism.

7. Slide 43 - Types of fossils Petrified Fossil Casts Imprint

8. Slide 44 Amber-Preserved Ice - Preserved

9. Slide 45 - Fast Fact! About 99% of species that have lived on Earth are extinct.

10. Slide 46 - How old are fossils? Relative Dating  Fossils found in layers closer to the surface are younger than the deeper layers. Radiometric Dating  Measuring how much of an element is still present in a fossil, using the half life.

11. Slide 47 - Half Life Amount of time it takes for a radioactive element to decrease by half.

12. Slide 48 - Paleontologist Person who studies fossils.  Size of Animal  How they moved  What they ate.  What climate they lived in.  When organisms lived.

13. Slide 49 - Plate Tectonics Plate = Earth’s Crust Tectonics = Movement Plate Tectonics = When Earth’s crust moves Crust floats on the mantle which is composed of molten (melted) rock. Crust is divided into plates! Constantly moving (10 cm/year)

14. Slide 50 - Pangaea “All Land” All continents were once joined together.

15. Slide 51 - Pangaea Separated into Laurasia and Gondwana.

16. Slide 52 - Earth Today Now 7 continents As continents moved and surrounded by ocean, land species became isolated and evolve differently. Australia has some of the most unique species in the world because it is so isolated.

17. Slide 53 - Australia Since it is so isolated from any other land, it has very unique species.

18. Slide 54 - Stop and Think Equator = Warmest place on Earth. Poles = Coldest Place on Earth

19. Slide 55 - Fossil Record Ordered levels of fossils in rock. Indicates that organism have evolved in sequence.