geological time scale

• Hadean

  • Greek God Hades
  • Earth's earliest history
  • Molten surface, volcanism, asteroids impact
• Geological Time Scale


  Record of life forms and geological events on earth
• Epoch


  Time shorter than period but longer than age
• Era


  Time shorter than eon but longer than period
• Period

  Time shorter than era but longer than epoch
• Geological Time Scale is a record of life forms and geological events on earth
• Eon


  Largest unit of time
• Proterozoic


  • Great oxygen event, snowball earth, formation of supercontinent Rodina
  • Evolution of eukaryotic cells and multicellular organisms
  • Bacteria, Algae, Jellyfish
• Cambrian


  • Cambrian explosion (oceanic calcium, oxygen)
  • Invertebrates: sponge, trilobites (no backbone)
• Ordovician


  • First fish evolved - early bone fish
  • First plant
  • Plants colonize land for the first time but animals remain in the water
• Phanerozoic


  • Complex multicellular organisms first appeared
  • Supercontinent Pangea
• Paleozoic

  • Ancient life or old life
  • First vertebrate animals (backbone)
  • Life flourished through the sea
• Devonian


  • First seed plant - protected or stored food
  • Cartilage fish - golden era of fish
  • Vertebrates evolve - amphibians
• Silurian


  • Earliest land animal
  • Vascular plants
  • First jawed fish, shark, lung fish, lobe fish, arthropods
• Archean


  • Beginning of rock record
  • Earth cooled, clouds form, crust began to harden
  • First Life - Cyanobacteria
• Carboniferous


  • First amphibians (still produce in water)
  • First reptiles (produce on land)
  • Diversification of insects and arachnids
• Permian

  • Domination of reptiles
  • Plants and animals evolve in dryness (waxy leaves or leather to prevent water loss)
• Mesozoic


  • Middle life
  • Age of dinosaurs
  • Appearance of mammals and flowering plants
• Triassic

  • First dinosaur
  • First mammal
  • Huge seed fern and conifers dominated the forest
  • Pangea separated into Laurasia and Gondwana land
• Jurassic

  • Golden age of dinosaurs
  • Earliest bird
  • All major group animals evolved
  • First appearance of flowering plants
  • New insects to pollinate
• Cretaceous


  • Modern seed-bearing plants
  • Dinosaurs reached their peak size
  • Earth's climate; warm and poles lacked ice
• Cenozoic


  • Recent life
  • Age of mammals
  • Today
• Neogene

  • Mammals and birds evolved
  • First hominids evolved
• Tertiary

  • Domination of mammals
  • Earliest prehistoric humans
  • Domination of flowering plants
  • Grazing animals
• Holocene

  • Enter ice age
  • Homo erectus
  • Early humans colonize Eurasia
  • Neanderthals
  • Modern humans appear
• Quaternary


  ?
• Carboniferous (period)


  First amphibians and reptiles, diversification of insects and arachnids
• Devonian (period)


  First seed plants, cartilage fish, evolution of amphibians
• Extinction (Permian)


  Worst extinction in earth's history with 95% death rate, volcanic eruption impact
• Mesozoic (era)

  Age of dinosaurs, appearance of mammals and flowering plants
• Hadean (eon)


  Earth's earliest history with a molten surface, volcanism, and asteroid impacts
• Proterozoic (eon)


  Great oxygen event, snowball earth, evolution of eukaryotic cells and multicellular organisms
• Permian (period)


  Domination of reptiles, adaptation to dryness in plants and animals
• Cambrian (period)


  Cambrian explosion, invertebrates like sponges and trilobites
• Phanerozoic (eon)


  Complex multicellular organisms first appeared, supercontinent Pangea
• Paleozoic (era)


  First vertebrate animals, flourishing of life in the sea
• Archean (eon)


  Beginning of rock record with the formation of the Earth's crust and the appearance of Cyanobacteria
• Ordovician (period)


  First fish evolve, first plants, colonization of land by plants
• Silurian (period)


  Earliest land animals, vascular plants, first jawed fish and arthropods
• Jurassic (period)

  Golden age of dinosaurs, first birds, major animal groups evolved