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Geologic Time Line Hadean Era 4.5 to 3.8 BYA Forming of the Earths Crust • During Hadean time, the Earth and Solar System formed by coagulation and gravitational contraction from a large cloud of gas and dust around the sun, called an accretion disc. • The Earth and Moon formed rather late in this process, from a collision between two large bodies -- a marssized planetoid and a slightly larger body. The Earths atmosphere forms • Volcanic Off gassing is thought to have been responibile for the methane, CO2, ammonia atmosphere. • Water Vapor trapped in this atmoshere precipatated into new oceans. These filled with prokaryote life. Archean Era 4 to 2.5 BYA The continents form • Continental shields formed from volcanic activity. Continental plates formed with continental drift evident. • Diverse Microbial life flourished. Anaerobic atmosphere helped reduce the poisonous atmosphere allowing blue-green Cyanobacteria to produce oxygen. Theoretical succession of Primitive life LIFE (= Archaea?) |--Eubacteria `--Eukarya |--Chlorobionta (green plants) `--+--Fungi `--Metazoa (animals) |--Deuterostomata | |--Echinodermata | `--Vertebrata `--Protostomata |--Mollusca `-Arthropoda Proterozoic Era 2.5 to .5 BYA • • Atmospheric changes caused by cynobacteria drive the • Anaerobic life into few niches and allowing aerobic and euykaryotice life to flourish. Life from a Snowball. • The Super Continent of Rodinia formed. • There several extensive Ice ages. • This caused a “snowball earth” effect, that left the globe covered by ice at several thick. • This ended many primitive life forms but by the end of this era Metazoic life began. Paleozoic Era-565 to 225 Mya Cambrian to Early Silurian 565 to 488 MYA • The Supercontinent broke up with Gwondwanaland drifting south and Laurentia and Baltica drifting into the tropics. Warm Open shallow seas formed between the land masses. Burgess Shale Mid Cambrian BC Canada Cambrian Life The first Arthopods • Trilobites rule. • Many new species in the “Cambrian explosian.” Brachipoda and corals develop. Marine worms and Stromatolites Ordovician Life forms Ordovician Giants Horns of Coral • Rugose Coral are an Index fossil of the Ordivician. • Notochords develop, probably the first backbones. Silurian to mid Devonian 444 to 416 MYA • About a third of Gondwanaland broke off and drifted south, colliding with Laurentia to form the North American Continent. • Devonian Fossil site Shropshire England. Devonian Ice Free Norway. Silurian Life Ammonite, Belonmites and Ect. • Huge Cephalopods • Jawless Hag fish and Lampreys, • Water Scorpions and Trilobites • Reef Coral and Sponges Devonian Life Devonian Life leaves the Water • • • • • Sharks and other Chrodrichthyes develop Bony fish replace most jawed placodermi. Early Amphibians, (Blind worms etc.) Insects and plants on land. Carboniferous 359 to 299 MYA • Lauarasia formed by the late carboniferous. The shallow inner continental oceans became narrower. • Scottish coal and peat bogs. Carboniferous Forests Amphbians, Crocadilians. Reptiles • Tetrapods (Shown Below) Large Tropical Forest • Insects rule the land • Coelacanth – Lungfish journeys onto the land. • Amphibians radiate • Protogynosperms, cone bearing plants, horsetail and ferns. Permian and Pangaea 299 to 225 MYA • Laurasia, North american, Gwondawanaland, Siberia and China form the super contintent Pnagaea Permian Life Large Reptiles • Amphibians develop • Reptiles rule the water and the land. • Dimetrodon and Edaphosaurs are up to 18 feet long. Mass Extinction