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Geologic Timescale

Geologic Timescale. Archaean Eon. 4.6-2.5 billion years ago ( bya ) Earth’s origin 3.7 bya : First protobionts 3.5 bya : First Prokaryotes 2.5 bya : atmospheric Oxygen increases. Proterozoic Eon. 2.5 bya to 542 mya 2.2 bya : first Eukaryotes

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Geologic Timescale

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  1. Geologic Timescale

  2. Archaean Eon • 4.6-2.5 billion years ago (bya) • Earth’s origin • 3.7 bya: First protobionts • 3.5 bya: First Prokaryotes • 2.5 bya: atmospheric Oxygen increases

  3. Proterozoic Eon • 2.5 bya to 542 mya • 2.2 bya: first Eukaryotes • Prokaryotes with plastids, mitochondria, and DNA • 600 mya: algae and soft bodied invertebrate animals • Snow ball Earth Hypothesis: Life can only exist where sunlight can reach deep ocean (where there was no ice), like vents and plate boundaries

  4. Phanerozoic Eon • Eras: • Paleozoic: 542 mya to 251 mya • Mesozoic: 251 mya to 65 mya • Cenozoic: 65 mya to today • All of life evolves to current state • Two mass extinctions: • Permian • Cretaceous

  5. Paleozoic Era • Periods: • Cambrian: Cambrian explosion and diversity of species • Ordovician: Plants and Arthropods colonize land • Silurian: vascular plants diversify • Devonian: Bony Fish, tetrapods, insects • Carboniferous: GIANT FOREST OF VASCULAR, Reptiles • Permian: More reptiles, origin of modern insects, MASS EXTINCTION

  6. Permian Mass Extinction • 96% of marine species gone • Increased volcanic activity in modern day Siberia • More CO2 in atmosphere, warmed planet • Less difference in equator and poles, slowed ocean currents • No currents, less oxygen for marine life

  7. Mesozoic Era • Periods: • Triassic: Cone bearing plants, dinosaurs diversify, and mammal like reptiles • Jurassic: Continued dominance of Cone bearing plants and dinosaurs • Cretaceous: Flowering plants emerge, Mass Extinction

  8. Cretaceous Mass Extinction • 50 % of marine life gone, most land plants and dinosaurs gone • Theory: asteroid or comet hit modern day Mexico and created a cloud of dust on Earth • This dust became a layer of clay with Iridium, which is an element not common on Earth • There was also an increase in volcanic activity in India

  9. Cenozoic Era • Periods: • Paleogene: 65 - 23 mya • Diversity of mammals, birds and insects • Flowering plants become dominant • Origin of Primate groups • Neogene: 23 mya – today • Origin of genus Homo • Ice Ages • Modern Day

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