Outliving T-Rex

Question 1

What is the most famous mass extinction event

Answer 1

The Cretaceous-Tertiary even (~65Mya)
Dinosaurs (and much else e.g. ammonites/belemnites) were wiped out

Question 2

How many species went extinct in the Cretaceous-Tertiary even (~65Mya)

Answer 2

75-80% of species extinction worldwide

Question 3

Why is it important to study extinctions

Answer 3

Studying past environmental crises can help us understand mechanisms of extinction and differential patterns of survival

Question 4

What caused the Cretaceous-Tertiary (K-T) extinction

Answer 4

Most think a bolide hit the Earth and caused/contributed to the extinction (A bolide is a meteorite from an asteriod belt)
Others think, the eruption of the Deccan Traps (a large Igenous provice) in India
Probably both

Question 5

What evidence is there for a bolide hitting the Earth

Answer 5

• Cretaceous and Teriary limestone shown
• The guy on the right has his hand on a layer of clay which has massive amounts of iridium in it - mostly present in Earth’s core
• The bolide distributed the iridium upon impact from the core

Question 6

What was the major effect of the K-T mass extinction

Answer 6

All large terrestrial animals (dinosaurs) and most large fresh water animals all died
As well as some small mammals, birds, amphibians and reptiles
This created a large change because dinosaurs where the most dominant species BUT many freshwater tetradpods survived suggesting a resilliance to environmental stressors

Question 7

What would have been the effects of the bolide impact

Answer 7

• Near the creater, there would have been rapid incinceration due to the intense heat
• This created wildfires which spread across the world - removing terrestrial vegetation
• Blackouts from the soot would have occured, effecting every continent - photosynthesis shuts down and the ‘green’ food chain collapses

Question 8

Which were the most vulnerable individuals from the bolide impact

Answer 8

• Vegetable eaters
• Eaters of vegetable eaters
• Those requiring lots of food regularly (warm-blood)

Question 9

Which individuals were less vulnerable from the bolide impact

Answer 9

• Detritus eaters
• Eaters of detritus-eaters
• Diggers for roots, tubers, seeds
• Those able to fast for long periods (cold-bloods)

Question 10

Why were marine organisms more resistant to extinction pressures than terrestrial organisms

Answer 10

• Freshwater systems are fuelled by both green and brown food chains
• Green: photosynthesis/algae and Brown: organic detritus
• Meaning when the Green food chain collapsed due to the bolide, the brown chains kept functioning in freshwater systems

Question 11

What are the main factors promoting survival through mass extinctions

Answer 11

• Large geographic range
• High abundance
• Habitat/food generalism
• Low resource requirements

Question 11

What are the main factors promoting survival through mass extinctions

Answer 11

• Large geographic range
• High abundance
• Habitat/food generalism
• Low resource requirements

Question 12

What is the biology of survival

Answer 12

A organism being able to survive in their non-preferred habitats
Being able to move from geographic range to the borders is critical to species survival and reproduction
This is why cold-bloods could survive more than warm-bloods because they can fast through long lean periods in unfavourable conditions
An example of this is Crocodilians and river dolphins