bio 2

• Earth's timeline and emergence of life


  System of dating the history of earth in a chronological manner using geological data
• Geological time scale


  • Eons
  • Eras
  • Periods
  • Epochs
• Eons


  • Phanerozoic eon, Precambrian eon
• Epochs


  • Shortest subdivision unit, changes in life forms and may vary from continent to continent
• Precambrian


  • Proterozoic
  • Archean
  • Hadean
• Proterozoic


  Formation of supercontinent Rodinia, the evolution of eukaryotic cells and multicellular organisms
• Archean


  Earth's crust cooled enough that rocks and continental plates began to form
• Hadean


  Referring to the hellish conditions, volcanic eruption
• Phanerozoic


  • Cenozoic
  • Mesozoic
  • Paleozoic
• Cenozoic


  Age of mammals
• Mesozoic


  Age of reptiles
• Paleozoic


  Age of invertebrates
• Periods in Paleozoic eon

  • Cambrian
  • Ordovician
  • Silurian
  • Devonian
  • Carboniferous
  • Permian
• Cambrian


  Major groups of animals first appear in the fossil record (Cambrian explosion), diversity of life forms
• Ordovician


  Variety of marine life, first primitive plants began to appear on land
• Silurian


  The rise of coral reefs, increase in the stabilization of global temperatures and climate, first appearance of land plants
• Devonian


  Age of fishes
• Carboniferous


  Coal beds began to form when faunal life became established on land, first seed plants and first reptiles appeared
• Permian


  The emergence of the supercontinent of Pangaea, severe extremes of climate and environment due to its vast size, 90% extinction of earth's species
• Theories regarding the origin of life on earth

  • Spontaneous generation theory
  • Primordial soup theory
  • Theory of panspermia
• Stromatolite fossils are the earliest known evidence on earth
• Life during Precambrian era

  • Proterozoic
  • Neoproterozoic
  • Mesoproterozoic
  • Paleoproterozoic
  • Archean
  • Hadean
• During the Paleozoic era, there were six major continents landmasses (Asia, south America, Europe, India, Antarctica, and north America), Pannotia was broken into pieces leading to the formation of Pangea
• Paleozoic era


  Characterized by the explosion of different life forms that started to emerge on earth
• Life forms in Precambrian era

  • Ediacarans (dickinsonia)
• Life forms in Paleozoic era

  • Vertebrates
  • Trilobites
  • Crinoids
  • Echinoderms
  • Brachiopods
  • Graptolites
  • Rugose corals
  • Acanthostega
• ICS - International Commission on stratigraphy
• Primitive microbial colony found in Australia
• Mesozoic era


  Famous for the presence of dinosaur
• Mesozoic era


  • Lasted 180 million years, estimated span 250 to 65 million years
• Periods in Mesozoic era


  • Triassic
  • Jurassic
  • Cretaceous
• Triassic


  250 MA (Mega annum- 1 million year)
• Cretaceous


  65 MA
• Plate tectonics


  • Permian (225 MYA) - land masses still intact = pangaea
  • Triassic (200 MYA) - 2 continent, laurasia and gondwanaland
  • Present (quaternary period) - 7 continents, human evolution
• Environment during Mesozoic era


  Unusually warm, polar ice caps were not yet formed, Pangaea located at the equator
• Triassic period


  Generally warm, continents still connects as one, presence of crocodilians, flying reptiles, sea-reptiles, mammals, diversity of dinosaur
• Jurassic period


  Two continent (laurasia and gondwanaland), dominant species and evolved to be gigantic dominant
• Cretaceous period


  Flowering plants (angiosperm) began to show for the first time
• Plants in early Mesozoic

  • Ginkgophytes
  • Cycads
  • Ferns