Mass Extinctions Flashcards
How many mass extinctions are in Earth’s known history? What are they known as?
Five, known as “The Big Five”.
What are the requirements for a period to be considered as one of mass extinction?
At least 75% of species go extinct in a geologically short period of time, typically less than 2.8 million years.
What are the names of the 5 mass extinctions, in chronological order?
Ordovician, Devonian, Permian, Triassic, Cretaceous.
How long ago was the Ordovician extinction? What percentage of Earth’s species went extinct in this period?
444 million years ago. 86% of Earth’s species disappeared.
How long ago was the Devonian extinction? What percentage of Earth’s species went extinct in this period?
360 million years ago. 75% of species went extinct.
How long ago was the Permian extinction? What percentage of Earth’s species went extinct in this period?
250 million years ago. 96% of Earth’s species disappeared, making it the most devastating mass extinction event in Earth’s history.
How long ago was the Triassic extinction? What percentage of Earth’s species went extinct in this period?
200 million years ago. 80% of species went extinct.
How long ago was the Cretaceous extinction? What percentage of Earth’s species went extinct in this period?
65 million years ago. 76% of the species on Earth went extinct.
Which mass extinction event caused the extinction of dinosaurs?
The Cretaceous.
What caused the Ordovician mass extinction?
Intense glacial periods locked away a large portion of the Earth’s water, killing most ocean life.
What caused the Devonian mass extinction?
As life spread onto dry land, plants transformed rubble into dirt, running nutrients into the water which contained a large majority of Earth’s species. These nutrients allowed the growth of algae, which deprived marine species of oxygen.
What caused the Permian mass extinction?
Intense volcanic activity in modern-day Siberia released large amounts of CO2 and sulphur, triggering extreme global warming and ocean acidification.
What caused the Triassic mass extinction?
Similar to the Permian mass extinction, volcanoes caused extreme global warming and ocean acidification.
What caused the Cretaceous mass extinction?
An asteroid 13 kilometers wide crashed into modern-day Yucatán, Mexico at 72000 km/h, leaving a 19 kilometer-deep crater. The debris were hurled into the atmosphere, blocking out the sun and causing Earth’s temperatures to decrease dramatically.
What is the Holocene extinction?
It is the mass extinction period Earth is currently experiencing. It started about 10,000 years ago and is now being exacerbated by human activity.
