| Scientists have concrete evidence that
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| | The Triassic-Jurassic Extinction occurred
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| the Earth is currently undergoing the
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| | 200 million years ago.
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| largest mass extinction in 65 million
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| | Was it caused by climate change,
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| years. Over 50 species are going extinct
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| | asteroids, or volcanoes? The verdict
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| every single day.
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| | isn't clear. What is clear is that 20% of
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| It's called the Holocene Extinction -
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| | marine life and many large amphibians
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| Holocene being the current epoch that
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| | were wiped out. At least half of all
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| began at the end of the last ice age,
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| | species on the planet bit the dust.
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| about 10,000 years ago.
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| | This event occurred over less than a
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| From Earth's fossil record, we know about
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| | 10,000 year period, just before the
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| Six Great Mass Extinctions:
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| | supercontinent of Pangea began to break
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| The Ordovician-Silurian Extinction
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| | up.
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| occurred about 444 million years ago.
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| | The Cretaceous-Tertiary Extinction
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| At the time, all complex organisms lived
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| | occurred about 65 million years ago.
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| in the sea. The most common theory is
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| | This event was probably caused, or at the
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| that the onset of an ice age caused the
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| | least aggravated by, the impact of an
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| extinction, which wiped out over 100
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| | asteroid around the size of Manhattan.
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| families of marine life. Many trilobite
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| | About 16% of marine families and 18% of
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| families bit the dust during this event.
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| | land vertebrate families ceased to exist.
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| The Late Devonian Extinction happened 364
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| | In North America, over 50% of plant
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| million years ago.
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| | species may have been wiped out.
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| This event saw a major worldwide
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| | And of course...this is the event that
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| extinction of coral reefs and the marine
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| | doomed the dinosaurs.
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| life they supported, as well as other
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| | The Holocene Extinction is occurring now.
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| groups of animals and plants. Nobody's
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| | Studies of the fossil record show that
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| sure what caused it, but scientists
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| | the normal "background" rate of
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| speculate global cooling and several
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| | extinction is about one species every
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| medium-sized asteroid impacts within a
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| | four years. The current rate is between
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| few million years of each other may have
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| | 30,000 and 100,000 per year.
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| been the culprits.
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| | You are now witnessing the fastest of the
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| The Permo-Triassic Extinction occurred
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| | six great mass extinctions.
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| 251 million years ago.
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| | And this extinction, without a doubt, is
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| The granddaddy of all mass extinctions,
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| | the result of human population growth. By
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| this event saw 96% of all marine species
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| | the end of this century, over five
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| and 70% of land vertebrate species kick
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| | million species (half of the species on
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| the evolutionary bucket.
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| | Earth now) will likely be gone.
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| The die off happened in less than a
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| | "It's not just species on islands or in
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| million years (a very short time in
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| | rain forests or just birds or big
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| geological terms) and the recovery took 5
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| | charismatic mammals," says Stuart Pimm, a
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| million years to crank back up, and
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| | conservation biologist researcher from
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| another million years after that to get
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| | the University of Tennessee. He notes
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| rolling. While not deemed the smoking gun
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| | fish, birds, insects, plants, and
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| yet, this event coincides with the
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| | mammals. "It's everything and it's
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| largest known volcanic eruption in
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| | everywhere...it is a worldwide epidemic
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| history.
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| | of extinctions.
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