Week 11 Intro

Question 1

Species

Answer 1

A group of organisms capable of interbreeding to produce fertile offspring

Question 2

Biodiversity

Answer 2

The variation of life forms within a given ecosystem or even on the entire Earth.

Question 3

Extinction

Answer 3

The end of an organism or group. The moment of death of the last individual marks the extinction, but because that is virtually impossible to determine, we define that last death by projection of population decline.

Question 4

Background Extinctions

Answer 4

Extinctions caused by moderate environmental changes or normal biological interactions. It is estimated that 99.9% of all species to ever exist are now extinct. Species become extinct when they are no longer able to adapt to changes in the environment or against superior species.

Question 5

Mass Extinction

Answer 5

• The event must be global in extent;
• All ecologies (marine and terrestrial) must be involved;
• The time of the event must be short – certainly less than 1 million years;
• A large number of species must become extinct; normally, we accept that the number
  must exceed 30% of the total species existing at the time.

Question 6

Mass Extinction End Ordovician Time

Answer 6

443.7 mya; approximately 85% of all existing species became extinct over two closely-spaced events.
1/5 extinctions of Phanerozoic Eon.

Question 7

Mass Extinction Late Devonian Time

Answer 7

370 and 360 mya; from 50 to 72% extinction rate each. Together, 2/5 of Phanerozoic.

Question 8

Mass Extinction End Permian Time

Answer 8

251 mya; 96% extinction of all marine and more than 70% extinction of all
terrestrial species. Near eradication of all life on Earth. 3/5 of the ‘big 5’.

Question 9

Mass Extinction End Triassic Time

Answer 9

201.8 mya; approximately 55-65% species extinction.
4/5 of the ‘big 5’.

Question 10

Mass Extinction End Cretaceous Time

Answer 10

65.5 mya; 65-75% species extinction (including dinosaurs). 5/5 of the ‘big 5’.

Question 11

Mass Extinction Holocene Time

Answer 11

Current, this is considered one of the most rapid and most devastating of
extinctions, and the causes are all linked to human activities and practices

Question 12

Mass Extinction Causes

Answer 12

• Flood Basalts
• Sea Level Rising
• Impact Events
• Sustained and Significant Climate Change
• Methane Clathrates
• Anoxic Ocean Water

Question 13

Mass Extinction Causes

Answer 13

• Flood Basalts
• Sea Level Rising
• Impact Events
• Sustained and Significant Climate Change
• Methane Clathrates
• Anoxic Ocean Water

Question 14

26 Million Year Correlation

Answer 14

• Raup and Sepkoski (1984) claim to see a 26 million year periodicity in extinction patterns over the past 250 million years
• No real evidence

Question 15

33 Million Year Correlation

Answer 15

• Stothers and Rampino (NASA)
• Periodicity in flood basalts, large impacts,
  magnetic field reversals, and mass extinctions
• They claim that periodicity to be 33 ± 3