The Cretaceous-Teritary Mass Extinction (L28)

Question 1

What does K-T mass extinction stand for?

Answer 1

Cretaceous-Teritary mass extinction

Question 2

What are the 3 factors that effected the K-T mass extinction?

Answer 2

Asteroid Impact
Volcanism
and Sea Level Change

Question 3

What was an element that was shown to have a dramatic increase at the K-T boundary and what is interesting about it?

Answer 3

Iridium

irdium is chemically inert so didn’t cause the mass extinction

Question 4

What do marine fossils show about the K-T boundary and what does this suggest?

Answer 4

there was a dramatic change in size and diversity and suggest that a major biological criss occured at this time

Question 5

What is a piece of proof that there was a bolide impact at the K-T boundary?

Answer 5

grains of quartz (shocked quartz) and peculiar criss-crossed lines (shock lamellae) were found in the boundary layer which are only found in high temps and pressures from exploisions

glass like material found (molten and cooled very quickly)

soot particles

lack of vegetation after impact

Question 6

What does the presence of glass in the boundary layer indicate?

Answer 6

that they were once molten and cooled very quickly

Question 7

What does the trench-like feature on the edge of the structure suggest?

Answer 7

suggests impactor came in at a relatively shallow angle to the ground

Question 8

What is an impact winter?

Answer 8

the earth entering darkness and cold for at least several months as debris is ejected into the atmosphere and creating extreme pollution

Question 9

How did impact winter create death by starvation?

Answer 9

plants would die, then plant-eaters would starve, and without plant-eaters, meat eaters would have starved

Question 10

How would impact winter create acidic death?

Answer 10

the rock anhydrite got hit by the impact and this rock is basically gypsum and

when gypsum is heated, it produces sulphur dioxide gas and when this sulphur reacts with water in the atmosphere, creates acid

and acid rain would dissolve the calcite meaning every organism with a calcium carbonate shell would have died

Question 11

How would impact winter create negative effects by vapourization?

Answer 11

the vapor of rock would hvae consumed oxygen, including oxygen in the form of ozone

ozone protects us from radiation from the sun. meaning that anything that survived impact winter would have faced tissue damage

Question 12

What is the Deccan Traps?

Answer 12

A giant stack of laval flows that is referred to this name b/c of their stepped appearance in natural exposures

Question 13

What is flood basalt volcanism associated with?

Answer 13

rising heat plumes from the mantle

Question 14

What is one of the first hypotheses put forward on what caused the K-T mass extinction?

Answer 14

Sea Level Change was the cause

Question 15

How did Sea Level Change hypothesis work?

Answer 15

a major sea level change occured near the end of the Cretaceous Period

the continental shelf areas became narrower as sea-level fell, causing an ecological crunch due to losso f living space and food resources

this would have forced organisms into competition for food and space, reducing diversity

less rainfall also reduced diversity of land animals even further

this may have allowed land animals to invade other continents carrying diseases that the native fauna weren’t immune to, reducing the native populations

Question 16

To sum it up, how did K-T mass extinction occur?

Answer 16

the biosphere was probably already weakened by volcanic activity, global cooling and sea level fall, and the asteroid impact at the very end of the Cretaceous was simply the final nail

Question 17

What happened with the dinosaurs becoming extinct?

Answer 17

there was a power change in land animals, the mammals smaller than dinos were no longer “oppressed” by the dinos and evolved quickly to fill in the niches that the dinos were removed from, making them big