Chapter 16: Precambrian Time Extinctions

Question 1

Approximately when did early life take hold?

Answer 1

After the heavy bombardment (beginning of the archean eon)

Question 2

Was there oxygen in this period?

Answer 2

No, only simple life forms were supported (prokaryotes)

Question 3

When did the oxygen catastrophe occur?

Answer 3

2400 mya

Question 4

What caused the access amount of O2 in the atmosphere?

Answer 4

Prokaryotes produced oxygen as a waste product of photosynthesis

Question 5

What metal would oxygen combine with?

Answer 5

Iron to from and iron oxide precipitate removing oxygen from the environment

Question 6

What happened when excess oxygen began to escape the oceans?

Answer 6

Accumulate int he atmosphere, but levels were so high that the excess was being returned to the water which caused catastrophic deaths
-1st mass extinction

Question 7

Snowball earth extinction, did it happen?

Answer 7

May have included several stages rather than one single event
Or no event because life seemed to flourish at this time

Question 8

When did the extinction of life occur?

Answer 8

At the end of the precambrian