Examples Of Extinction Events

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5 Major Extinction Events in Earth’s History Earth has had many extinction events in its life time, but there are 5 events that have been named major events due to the extreme amount of species that were killed off due to the event. The events, in order from first occurring to most recent, are the Ordovician – Silurian Extinction event (450-440 MA), the Late Devonian Extinction (375-360 Ma), the Permian – Triassic Extinction Event (252 Ma), the Triassic – Jurassic Extinction Event (201.3 Ma), and the Cretaceous – Paleogene Extinction Event (66 Ma). The events are ranked by the % of species that were made extinct due to the event. The first event, the Ordovician – Silurian extinction event, which occurred 450-440 Ma was actually two events in…show more content…
This particular extinction event is name the “Great Dying” as it was the largest extinction event in Earth’s history. This event had huge evolutionary benefits however as it ended primacy in mammal life reptiles. It is hard to pinpoint an exact cause for the event as most of the evidence has either been buried in the Earth or destroyed over time. Evidence of asteroid impacts have been found, but are not fully agreed upon in the scientific community. Other, more agreed upon, evidence suggests that volcanism was a major factor in the Permian – Triassic event. The specific event that is well known is the volcanic eruption that created the Siberian Traps which covered over 2 000 000 square kilometres with lava. Volcanoes would have also spewed dust into the air and blocked photosynthesis in plants thus breaking multiple food chains. Acids rain would have been present killing plants and poisoning water sources and killing off certain species that live in water. Carbon dioxide would have been released causing global warming which would have continued even after the dust cleared and the acid rain washed away. Evidence of anoxia is also found as well as euxinia (hydrogen sulphide). These two phenomena are believed to have killed off most of the marine life of this…show more content…
During this event 75% of all species were killed. Mostly terrestrial life was killed, which made way for dinosaurs to become the dominant life form on Earth. The causes for this extinction event are mostly theories as there is a lack of evidence to prove that anything specific happed for certain. Climate change is suggested as well as an asteroid impact, but no evidence of craters or why there was a sudden loss in marine life are evident. Volcanic eruptions would have released CO2 or SO2 and aerosols which would have created global warming or cooling respectively. These are all still theories, but volcanic activity is the most likely cause for the extinction event during this time

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