http://www.bbc.co.uk/nature/history_of_the_earth

Ordovician-Silurian Mass Extinction:

440 million years ago

Ordovician-Silurian Mass Extinction

• 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

• 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.

Late Devonian Mass Extinction:360 million years

ago

Permian Mass Extinction:250 million years ago

Permian Mass Extinction:250 million years ago

• 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• 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• 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