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1 CE
Today
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66
The Cretaceous Extinction
Cause: impact of massive comet or asteroid. Heat wave and shocks upon impact, fell back on earth and caused destruction
Earth Conditions: T-rex, theropods, herbivores
Evidence: A 180 km of crater was also found in Mexico, a high level of iridium, which is abundant in asteroids. Fossil records
Result: ~80% of the earth’s species lost
Terrestrial vertebrate, invertebrate, and plants, many marine invertebrates died.Tertiary, alligators, crocodiles, birds, frogs and salamanders survived. -
210
the Triassic Extinction
Earth Conditions: C-shape Pangea. 199 MYA, plate tectonics split Pangea into 2 land masses (Laurasia and Gondwana)
~90% of earth’s species therapids and reptiles archosaurs extinct
Cause: Climate change, rising sea level, release of CO2 from volcanic activity.
Fun Fact: Evolution of dinosaurs; the event opened niches which were filled by dinosaurs and made them the dominant species. First period of the Mesozoic Era where terrestrial life began to diversify -
252
The Permian Extinction
The mother of all extinctions
95% of all marine life and 70% of all terrestrial life lost
Immobile organisms died out
Duration of the extinction event is unclear: 15 MY to 200,000 Y
Cause: Temperature crises due to the disruption of chemical cycles. Methane-producing microbes caused widespread suffocation. Oceans became deprived of O2
Earth Conditions: Pangea emerged, landmass and ocean currents drastically changed
Evidence:
Fun Fact: -
364
The Devonian Extinction
The Era of the Fishes!
Earth Conditions: marine, 10 m long sea creatures, the Dunkleosteus, Placoderms; fish with jaws, gills, and fins; ancient ancestors of sharks
Cause: plants strangled the ocean to death.The development of plants changed ground minerals and atmospheric conditions. The anoxic zone suffocated marine species
~70-80% species lost
After the Devonian, land species evolved
Fun Fact: some Devonian era species are still kicking around, such as the Elephant shark. -
443
The Ordovician Extinction
Occurred ~443 MYA
~85% of species went extinct
~60% of all marine life
~25% of invertebrates.
1/3 of all brachiopod and bryozoan families, as well as numerous groups of conodonts, trilobites, and graptolites, as well as reef-building fauna.
Causes: The first wave of extinction was caused by climate change as extreme cooling lead to the glaciation of Gondwana and lowered sea levels. Then, the second wave occurred as the climate warmed at the end of the ice age.
Evidence:
