Transcript Ordovician-Silurian Mass Extinction: 440 million years

http://www.bbc.co.uk/nature/history_of_the_earth
Ordovician-Silurian Mass
Extinction:
440 million years ago
Ordovician-Silurian Mass
Extinction
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3rd largest extinction in Earth’s history
Actually had two peaks in which the
extinction was the greatest over
hundreds of thousands of years.
During this time, most life on Earth
existed in the oceans which is where
the most damage occurred.
Nearly 85% of sea life was wiped out
The reason? The most accepted
cause of this extinction was an ice
age that not only caused drastic
cooling but it caused sea-levels to
drop
Late Devonian Mass Extinction:
360 million years ago
Late Devonian Mass
Extinction:
360 million years ago
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Also known as the “Kellwasser Event”
75% of all species on Earth died out
Believed to have been a series of extinctions over millions of
years
Marine life was the worse affected with coral reefs suffering
the most. Actually, coral reefs didn’t rebound until well over
a 100 m.y. later!
Bacteria was practically the only organism that could survive
in the oxygen deprived oceans
Unknown cause  theories include climate change, asteroid
impact, invasion of new species affecting surrounding
ecosystems.
Permian Mass Extinction:
250 million years ago
Permian Mass Extinction:
250 million years ago
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Nicknamed “The Great Dying” for being the largest
mass extinction in Earth’s history
Killed 96% of marine life and 70% of terrestrial
vertebrates
Most likely happened over millions of years with several
waves of extinction, as opposed to one large event
Only mass extinction known to affect insects
Possible Causes  first phase was probably due to
global climate change, then increased volcanism,
abundant release of methane which led to anoxia,
sea-level change, a possibly a shift in ocean circulation
due to climate change.
Triassic-Jurassic Mass Extinction:
200 million years ago
Triassic-Jurassic Mass Extinction:
200 million years ago
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2 to 3 phases of this extinction over 18 m.y.
Many animals died out; marine reptiles, amphibians, some
reef-building communities
About 50% of all life was predicted to have died out
Plants, mysteriously, were not affected very much
Cretaceous-Tertiary Mass Extinction:
65 million years ago
Cretaceous-Tertiary Mass Extinction:
65 million years ago
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Also known as the K-T Mass Extinction
Famous for the death of the dinosaurs
Dinos, however, weren’t the only organisms to go
extinct
• Ammonites
• Many flowering plants (angiosperms)
• Pterosaurs
Theorized that flood basalt eruptions severely
affected climate change and caused many of these
species to be on the decline well before this
extinction
Huge asteroid hit in Yucatan Peninsula which pushed
these dwindling species over the edge