And changes in organisms Geologic Time And changes in organisms

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

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

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

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

Cambrian 543-490 mya Trilobites, echinodermata, brachiopods, sponges, worms, bacteria All life in oceans First vertebrates at end

Ordovician 490-443 mya Primitive fish, cephalopods, trilobites, corals, crinoids Climate warm, but as Gondwana moved to S Pole, became cooler

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

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

Carboniferous 354-290 mya Insects, reptiles (amniote egg) and swampy forests develop on land Brachiopods, gastropods, bony fish, sharks common in marine environment

Carboniferous

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