Paleogeography and paleoclimates

Question 1

GABI

Answer 1

Great American Biotic Interchange
1. 2.8 mya
2. North American fauna invades the south
3. South American fauna invades the north

Question 2

BIME

Answer 2

Biotic Immigration Events
1. Initial colonisation increase alpha (within community ) diversity at the expense of beta (between community) diversity. Gamma (global) diversity remains unchanged.
2. With insolation speciation occurs in all three diversity metrics

Question 3

What is vicariance?

Answer 3

Seperation of an ancestral biota into two or more biota following a geographical barrier that stops gene flow (e.g. evolution of an ocean or mountain belt).

Question 4

What is dispersal?

Answer 4

The movement of organisms from place to place.
Works well when continents join

Question 5

Latitudinal diversity gradient (LDG)

Answer 5

Shows diversity trailing away symmetrically north and south from equator to poles

Question 6

Thermal maturation

Answer 6

Some microfossil change colour with changing paleotemperatures e.g. Conodonts

Question 7

Snowball Earth scenario

Answer 7

1. Continents are near the equator, increasing precipitation removes CO2 from atmosphere, and with falling temperatures ice begins to spread
2. Ice continues to spread, temperatures further reduced by albedo
3. Atmospheric CO2 increases due to volcanic activity, prompting a reversal in temperature
4. . Greenhouse conditions return and ice sheet recede

Question 7

Conodont alteration indices (CAI)

Answer 7

• Conodonts are good thermal indicators
• Light amber>gray>black and white>translucent
• CAI values from1-8 though temperature range of 60-600 degrees C

Question 7

Climate oscillation last 600 mya

Answer 7

during last 600 mya the Earth has oscillated at least five times between ice house and green house conditions