Extinction and global change

Question 1

what are the 5 mass extinction events in our planet’s history

Answer 1

1) Cretaceous-Tertiary (65 mya)
2) End triassic (200mya)
3) Permian Triassic (250 mya)
4) Late devonian (364mya)
5) ordovician silurian extinction (440mya)

Question 2

what is the difference between background and mass extinction

Answer 2

Background = extinction which occurs continually, generating a turn over of species living on Earth

mass = when extinction rates rise suddenly for a relatively short period of time, killing off many species

Question 3

outline some characteristics of the Ordovician- Silurian extinction 440 mya

Answer 3

26% of all marine families
60% of all genera
82-88% of all species died
WHY- an intense ice age brought about by the location of the supercontinent Gondwana over the southern pole

Question 4

outline some characteristics of the late devonian extinction 362mya

Answer 4

22% of all marine families
57% of all genera
79-87% of all species
WHY- time of massive environmental change with the first phase being linked to lack of oxygen in the ocean

Question 5

outline some characteristics of Triassic extinction

Answer 5

51% of marine families
82% of all genera
93-97% of all species
WHY- large landmass created very hot and dry conditions acorss most of interior

Question 6

outline characteristics of the end of triassic extinction 200mya

Answer 6

22% of marine families
53% of all genera
76-84% of all species
WHY- least understood due to lack of sediments but most evidence suggests falling sea levels

Question 7

outline some characteristics of the cretaceous tertiary extinction

Answer 7

16% of marine families
47% of all genera
71-81% of all species
large asteroid impact

Question 8

what are some human drivers of the current extinction

Answer 8

climate change
temperature
increased extreme events
increased sea levels
habitat destructions