12. Outliving T-rex

Question 1

Which extinction killed the dinosaurs?

Answer 1

End-Cretaceous

Question 2

What letter is sometimes used to represent the Cretaceous period to avoid confusion with the Carboniferous?

Answer 2

K

Question 3

When was the end cretaceous mass extinction?

Answer 3

65 Million Years ago

Question 4

What % of overall species went extinct in the end-cretaceous mass extinction?

Answer 4

75-80%

Question 5

What are the 2 main theories for the cause of the end-cretaceous extinction?

Answer 5

Bolide impact or eruption of the Deccan Traps in India

Question 6

What is a bolide?

Answer 6

A meteorite large enough to form an impact crater

Question 7

What evidence of environmental conditions was found in cretaceous-tertiary boundary clays? What do they evidence? What is the significance of their location?

Answer 7

Iridium, soot, charcoal, tektites
- Evidence of major environmental disruption e.g. wildfires
Found everywhere -> worldwide event

Question 8

What was the impact of the end-cretaceous extinction on land tetrapods?

Answer 8

All LARGE tetrapods on land died

Question 9

What was the impact of the end-cretaceous extinction on freshwater animals ?

Answer 9

Most large ones survived

Question 10

How large was the end-cretaceous bolide speculated to be?

Answer 10

10-12km diameter

Question 11

What was the quick impact of the bolide?

Answer 11

Nearby - incineration
Far away - wildfires and tsunamis

Question 12

What was the main long lasting effect of the bolide impact that affected everywhere?

Answer 12

Blackout

Question 13

What is the impact of a blackout on the world/ecosystems?

Answer 13

• Cold weather
• Photosynthesis shutting down
• Green food chain collapses
• Prevents unsprouted seeds from germinating

Question 14

What were the most vulnerable land groups in the end-cretaceous extinction?

Answer 14

Vegetable eaters, eaters of vegetable eaters, those requiring lots of food regularly (warmbloods)

Question 15

What were the least vulnerable land groups in the end-cretaceous extinction?

Answer 15

Detritus eaters, eaters of detritus eaters, diggers for roots, tubers and seeds, those able to fast for long periods (coldbloods)

Question 16

Why were freshwater systems more durable than land systems in the end-cretaceous extinction?

Answer 16

Freshwater systems are fuelled by both green and brown food chains and are able to survive when the green systems shut down.
- Systems are damaged but not driven to full extinction

Question 17

Who were the best survivors of the end-cretaceous extinction?

Answer 17

Small seed and invertebrate eaters, especially those plugged into brown food chain, and big freshwater predators at the top of a brown food chain.

Question 18

What are four main characteristics to increase survival through a mass extinction?

Answer 18

1. Large geographic range
2. High abundance
3. Habitat and food generalism
4. Low resource requirements

Question 19

What traits of cold-blooded animal populations are conducive to their good survival rates?

Answer 19

• Large numbers in favourable areas, which persist under harsh conditions
• Population needs less food than warm-blooded counterparts
• Small numbers even in unfavourable conditions (occupy a range of habitats)
• Can resupply between these regions to grow numbers after reduction

Question 20

What traits of warm-blooded animal populations make them less likely to survive extinction-type events?

Answer 20

• Need more food
• No breeding populations in unfavourable locations
• Smaller populations typically, in even favourable locations
• More vulnerable to local extinctions when conditions turn unfavourable
• No resupply

Question 21

What does the study of crocodiles over the last 50 ish years prove about coldbloods?

Answer 21

Crocodiles are very threatened by poaching and thus were predicted to have gone extinct 30 years ago, but still persist today
- Show resilience of cold blooded river animals

Question 22

What was studied to try and pinpoint a time of year for the beginning of the end-cretaceous extinction? What time does it suggest

Answer 22

Fish bones
- Annual growth lines in specific bones, these have peaks in the summer and show a cut off just before that
Suggests spring extinction

Question 23

What other research corroborates the findings from the fish-bones?

Answer 23

Carbon isotope records that show growth patterns

Question 24

Why is it so hard to compare severity of extinctions? (2 reasons)

Answer 24

Due to disparity in fossil records between periods
- Extinction usually described in terms of species, while fossils usually categorised by genus