1. And changes in organisms
Geologic Time
And changes in organisms

2. Precambrian Formation of Earth to Cambrian Explosion
Oldest known fossils: 3.5 bya (cyanobacteria)
Cyanobacteria begin to change atmosphere

3. Precambrian Oxygen build up about 2.2 bya
First eukaryotic cells approximately 1.8 bya
Dinoflagellates or algae: unicellular

4. Precambrian Vendian: 650-543 mya
Soft bodied multicellular organisms as well as unicellular organisms

5. Paleozoic 543-248 mya Began with Cambrian explosion
Ended with Permian extinction

6. Cambrian
mya
Trilobites, echinodermata, brachiopods, sponges, worms, bacteria
All life in oceans
First vertebrates at end

7. Ordovician
mya
Primitive fish, cephalopods, trilobites, corals, crinoids
Climate warm, but as Gondwana moved to S Pole, became cooler

8. Silurian 443-417 mya Relatively stable climate
First jawed fish, coral reefs, first land animals, first vascular plants

9. Devonian 417-354 mya Ferns, small bushes and first seed plants on land
First land vertebrates
Corals, brachiopods, fish dominant in oceans; fewer trilobites
Global cooling at end

10. Carboniferous
mya
Insects, reptiles (amniote egg) and swampy forests develop on land
Brachiopods, gastropods, bony fish, sharks common in marine environment

11. Carboniferous

12. Permian 290-248 mya Formation of Pangaea affects all living things
Mass extinction by the end (mainly marine)--90% of all species
Reptiles and gymnosperms on land