Mass Extinctions

Question 1

What is a mass extinction?

Answer 1

It is when many species die out over the same period of time

Question 2

How many mass extinctions have occurred since the creation of life on earth?

Answer 2

Five

Question 3

What are the five major mass extinctions?

Answer 3

End of Ordovician period
Late Devonian period
End of Permian period
End of Triassic period
End of Cretaceous period

Question 4

When did the mass extinction at the end of the Ordovician period occur?

Answer 4

435 mya

Question 5

What is special about the mass extinction at the end of the Ordovician period?

Answer 5

It is the second biggest mass extinction

Question 6

What was a possible cause of the mass extinction at the end of Ordovician period?

Answer 6

Climatic changes (ice age, with a possible drop in sea level)

Question 7

When did the mass extinction during the late Devonian period occur?

Answer 7

345 mya

Question 8

What caused the mass extinction late in the Devonian period?

Answer 8

The exact cause is unknown

It may have been an ice age with a drop in sea level

Question 9

When did the mass extinction at the end of the Permian period occur?

Answer 9

250 mya

Question 10

What caused the mass extinction at the end of the Permian period?

Answer 10

Climatic changes
Ice age
Volcanic eruptions
Flood
Comet or asteroid

Question 11

What was special about the mass extinction at the end of the Permian period?

Answer 11

It was the biggest mass extinction in history

About 90% of all life on earth was wiped out

Question 12

When did the mass extinction at the end of the Triassic period occur?

Answer 12

190 mya

Question 13

What caused the mass extinction at the end of the Triassic period?

Answer 13

It is uncertain

Could have been global warming, ice age or volcanic eruptions

Question 14

What happened after the mass extinction late in the Devonian period?

Answer 14

Amphibians became terrestrial

Question 15

What happened after the biggest mass extinction?

Answer 15

Reptiles replaced huge amphibians as the dominant group

Question 16

What was life like before the mass extinction at the end of the Ordovician period?

Answer 16

Until this time, life was limited to the water, with very little life on land

Question 17

What is special about the mass extinction at the end of the Triassic period?

Answer 17

The last of the big amphibians became extinct

Question 18

What happened after the mass extinction at the end of the Triassic period?

Answer 18

Dinosaurs were abundant

Question 19

When did the mass extinction at the end of the Cretaceous period occur?

Answer 19

65 mya

Question 20

What caused the mass extinction at the end of the Cretaceous period?

Answer 20

Possibly a meteorite collision with the earth

Volcanic eruptions

Question 21

Why do scientists think that a meteorite collision caused the mass extinction at the end of the Cretaceous period?

Answer 21

The Yucatan Peninsula seems to show evidence of the collision

Question 22

What is special about the mass extinction at the end of the Cretaceous period?

Answer 22

The dinosaurs became extinct

Marine ammonites became extinct

Question 23

What happened after the mass extinction at the end of the Cretaceous period?

Answer 23

Mammals increased and became the dominant group

Question 24

Why do scientists suspect volcanic eruptions caused the mass extinction at the end of the Cretaceous?

Answer 24

There is evidence of a high level of volcanic activity at that time

Question 25

Where was the main concentration of these volcanic eruptions?

Answer 25

In the Deccan region of India

Question 26

What probably caused this raised level of volcanic activity?

Answer 26

India was a separate mass of land drifting north

The collision with Asia probably caused it

Question 27

Why could volcanic activity cause a mass extinction?

Answer 27

Dust and ash released into the air could block out the sun’s rays
This led to a cooling of the atmosphere
Ice sheets were formed at the poles, sea levels dropped and the aquatic habitats decreased
Less photosynthesis occurred
O2 in the atmosphere decreased
The surface of the earth becomes submerged in CO2
This intensifies global warming (greenhouse effect)
Ice masses melt
Terrestrial habitats are flooded and destroyed

Question 28

What is a meteorite?

Answer 28

Mass of dust and rock moving through space

Question 29

What is an asteroid?

Answer 29

A meteorite with a diameter of more than one kilometre

Question 30

What is the asteroid impact theory?

Answer 30

A theory which speculates that the mass extinction at the end of the Cretaceous period was caused by an asteroid impact

Question 31

Why would an asteroid cause a mass extinction?

Answer 31

Dust and rubble would have been released into the air
It blocked the sun’s rays, which could ave caused an ice age
The heat of the impact would have led to the extinction of many plant and animal species including the dinosaurs
Organisms could not adapt to the ch aged environment and died out
Photosynthesis stopped:
Plants became extinct
When this food source was lost, many other animals died out
O2 levels dropped

Question 32

What other disasters would an asteroid impact have caused?

Answer 32

Worldwide fires
Huge tsunamis
Acid rain

Question 33

Why do some scientists say that modern time is the sixth mass extinction?

Answer 33

The present rate of extinction is higher than any during any time in the past

Question 34

How many species become extinct each year?

Answer 34

About 40 000

Question 35

What is the cause of this “sixth mass extinction”?

Answer 35

The negative impact of humans on the environment

Question 36

What is unique about this sixth mass extinction?

Answer 36

It is the only one with a biotic cause