Mass Extinctions Flashcards
What is a mass extinction?
It is when many species die out over the same period of time
How many mass extinctions have occurred since the creation of life on earth?
Five
What are the five major mass extinctions?
End of Ordovician period Late Devonian period End of Permian period End of Triassic period End of Cretaceous period
When did the mass extinction at the end of the Ordovician period occur?
435 mya
What is special about the mass extinction at the end of the Ordovician period?
It is the second biggest mass extinction
What was a possible cause of the mass extinction at the end of Ordovician period?
Climatic changes (ice age, with a possible drop in sea level)
When did the mass extinction during the late Devonian period occur?
345 mya
What caused the mass extinction late in the Devonian period?
The exact cause is unknown
It may have been an ice age with a drop in sea level
When did the mass extinction at the end of the Permian period occur?
250 mya
What caused the mass extinction at the end of the Permian period?
Climatic changes Ice age Volcanic eruptions Flood Comet or asteroid
What was special about the mass extinction at the end of the Permian period?
It was the biggest mass extinction in history
About 90% of all life on earth was wiped out
When did the mass extinction at the end of the Triassic period occur?
190 mya
What caused the mass extinction at the end of the Triassic period?
It is uncertain
Could have been global warming, ice age or volcanic eruptions
What happened after the mass extinction late in the Devonian period?
Amphibians became terrestrial
What happened after the biggest mass extinction?
Reptiles replaced huge amphibians as the dominant group
What was life like before the mass extinction at the end of the Ordovician period?
Until this time, life was limited to the water, with very little life on land
What is special about the mass extinction at the end of the Triassic period?
The last of the big amphibians became extinct
What happened after the mass extinction at the end of the Triassic period?
Dinosaurs were abundant
When did the mass extinction at the end of the Cretaceous period occur?
65 mya
What caused the mass extinction at the end of the Cretaceous period?
Possibly a meteorite collision with the earth
Volcanic eruptions
Why do scientists think that a meteorite collision caused the mass extinction at the end of the Cretaceous period?
The Yucatan Peninsula seems to show evidence of the collision
What is special about the mass extinction at the end of the Cretaceous period?
The dinosaurs became extinct
Marine ammonites became extinct
What happened after the mass extinction at the end of the Cretaceous period?
Mammals increased and became the dominant group
Why do scientists suspect volcanic eruptions caused the mass extinction at the end of the Cretaceous?
There is evidence of a high level of volcanic activity at that time