1. Chapter 14 Lesson 2
Early Earth History

2. PreCambrian Time Longest part of Earth’s history
Includes the Hadean, Archean, and Proterozoic Eons
Lasted from 4.5 billion years ago to 544 million years ago
Not much is known because the organisms did not have “hard parts” and could not withstand the heat and pressure

3. Early History
Characterized by stromatolites- layered mats of cyanobacteria
Cyanobacteria- blue green algae
Made their own food through photosynthesis
Important because they made oxygen for our current atmosphere
Ozone also started to appear to shield us from harmful UV rays

4. End of Precambrian era First invertebrates appear
They had soft bodies so their remains were not preserved as fossils.
First jelly fish, worms, and soft corals form

5. Paleozoic Era Organisms with hard shells are common
544 million years ago (mya) to 248 mya
Warm, shallow seas covered large areas
Trilobites common
Vertebrates appear in this Era
First vertebrates were fish like with jaws
Forests appear in Devonian period so land vertebrates appear

6. Life on Land Many of the fish had lungs and gills.
Many bottom dwellers may have had fins evolve into legs.
However, all amphibians must lay eggs in water or moist area.
Reptiles now evolve in the Pennsylvania period so these organisms no longer need a watery location to lay eggs.

7. Palezoic Era cont Mountain building occurs Appalachian Mountains form
The ocean separating North America from Europe and Africa closed
Several volcanic island chains that formed in ocean collided with North American plate
2nd mountain building- African plate collides with North American plate

8. Paleozoic Era
90 % of marine and 70 % of land species die off by the end of the era
Maybe caused by climate changes or lowering of sea levels.
Pangaea formed at this time and glaciers covered the southern part of Pangaea.
Other theories include extreme volcanic activity.
Giant comet or asteroid?