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The Earth's Major Extinction Periods

By bridget.blount2019
  • 444 BCE

    Ordovician Perioid

    Ordovician Perioid
    1.The more likely cause is that the Earth cooled, particularly the oceans where most of the organisms lived during the Ordovician.
    2. 85% of the animals went extinct
    3. blastoids, bryozoans, corals, crinoids, as well as many kinds of brachiopods, snails, clams, and cephalopods,

    4.The greatest extinctions occurred in the tropical oceans. There would be fewer regions warm enough to accommodate all the warm-preferring organisms.
  • 359 BCE

    Devonian

    Devonian
    1. Glaciation and the lowering of the global sea level may have triggered this crisis since the evidence suggests warm water marine species were most affected.
    2. 20 to 50 percent of all genera on Earth at that time may become extinct 3.
    3. there was no organic accumulation in the soils, resulting in soils with a reddish color. This is indicative of the underdeveloped landscape, probably colonized only by bacterial and algal mats.
  • 252 BCE

    Permian

    Permian
    1. Supercontinent separating disrupted the circulation of seawater, making the oceans stagnant.
    2. As many as 90 to 96% of the planet's marine species were lost, and 70% of the land's reptile, amphibian, insect, and plants species went extinct
    3. Dimetrodon, Eryops, Diplocaulus, archosaurs, amphibians, fish 4.interior regions of this vast continent were probably dry, with great seasonal fluctuations due to the lack of a moderating effect provided by nearby bodies of water
  • 199 BCE

    Triassic period

    Triassic period
    1. Massive volcanic eruptions from a large region known as the Central Atlantic spewed huge amounts of lava and gas. This global warming and acidification of the oceans that ultimately killed off thousands of plant and animal species.
    2. This massive extinction decimated 76 percent of marine and terrestrial species.
    3. Conodonts, Ostracods, Tetrapods, and Gastropods
    4. The land masses of the world were still bound together into the vast supercontinent known as Pangea.
  • 145 BCE

    Cretaceous Period

    Cretaceous Period
    1. An asteroid hit Earth in the Yucatan Peninsula, Mexico. It has been estimated that half of the world's species went extinct at about this time, but no accurate species count exists for all groups of organisms.
    2. 80% of all living animals went extinct
    3. conifers, cycads, and other gymnosperms, also most of the dinosaurs
    4. the supercontinent Pangea was already drifting apart, and by the mid-Cretaceous, it had split into several smaller continents.