Dinosaur Extinction

Question 1

K/T boundary

Answer 1

K/T: Cretaceous /Tertiary

Tertiary is outdated term

Question 2

K/Pg boundary

Answer 2

K/Pg Cretaceous / Paleogene
End of cretaceous / end of dinosaurs
Age of dinosaurs - k/Pg Boundary -> age of mammals

Question 3

K/Pg boundary and K/T boundary

Answer 3

They are the same thing

Question 4

Rock of K/Pg ( between age of dinosaurs and age of mammals)

Answer 4

Dark
A lot of things burnt?
Softer rock than other rock layers

Question 5

Spike in Iridium

Answer 5

Found usually from space or deep in earth

Not a lot found normally on earth’s surface

During K/Pg boundary, found A LOT of iridium

Found not only in Italy but around the world

Controversy about where it’s from but most like it’s ET (extraterrestrial)

Question 6

Was there a gradual decline of dinosaur diversity before the K/T boundary?

Answer 6

More genera in Cam than Maa

But it depends on rock availability

Question 7

Errors with rock availability and measuring decline of dinosaur diversity

Answer 7

But it depends on rock availability:

Bias of sampling
Suggests no decline in diversity

Statistical errors b/c of little sample size

No consistency in results
Statistically did NOT decrease gradually (dinosaurs were doing fine before the extinction)

Question 8

What are the Deccan Traps?

Answer 8

LARGE Body of lava found in India

Huge chunk of lava covering large area

Question 9

Deccan Traps and Magma

Answer 9

To cover a size that large, you need a lot of magma
Mantle

Molten rocks become magma
Magma seeps through crust to make volcanoes

Because there aren’t enough cracks, the magma keeps building up

The older the magma, the smoother it is
Therefore, when it comes out, it doesn’t stop flowing -> covers a much larger area

Question 10

Erruptions of the Deccan Traps and K/Pg boundary

Answer 10

1st eruption before K/Pg boundary
Last eruption after K/Pg boundary

Deccan traps on and off during that time period
Deccan traps most likely resting before impact

Question 11

What is the Chicxulub Crater?

Answer 11

Crater (Mexico?)
Half on sea, half on land
Scientists looked for crater after iridium spike

Question 12

Gravity anomaly in the Chicxulub Crater?

Answer 12

Gravity is actually not constant
We can calculate subtleties in gravity

Found gravity anomaly in crater
Majority of crater sill there

Question 13

Asteroid impact and its leftovers

Answer 13

Asteroid (which created the crater) impact was so strong, it melted everything around it

Estimates of asteroid diameter = 10 km

Left behind dark layer - carbon leftover

Question 14

Asteroid impact at an angle?

Answer 14

The asteroid hit at an angle

So the molten stuff went more in one direction than in another

Question 15

Immediate Aftermath and resulting effects of the asteroid impact?

Answer 15

Ignites fires
Melted the limestone under the surface
Got to the rocks easily
Released a MASSIVE tidal wave
Water couldn’t stop the fires because it went in the different area

Question 16

Deccan Traps and the asteroid?

Answer 16

2 different things happened in India and mexico @ the same time

Question 17

Was it an instantaneous kill?

Answer 17

Wasn’t an instant thing
Probably tooks years, centuries, etc.
Long time compared to us but a short time period in terms of everything else

Question 18

Mass extinction

Answer 18

Mass extinction: 75% of all species died
All non bird dinosaurs died
Difficult to kill a lot all at once

Question 19

What most likely happened during the Mass extinction - from the deccan traps and the asteroid?

Answer 19

Probably ignited fires all over world

Probably why we see black @ K/Pg Boundary in rock

Question 20

After effects of this beginning of the mass extinction?

Answer 20

Acid rain
Nuclear winter
Greenhouse effect

Question 21

Acid rain

Answer 21

When the heat melted the limestone, it got absorbed into the air leading to acid rain
Weeks of acid rain

Question 22

Nuclear winter

Answer 22

Happened first few weeks

The soot of burning gets into air -> blocks the sun
Shields the sun

Plants cannot survive long w/o sun
If plants die, dinosaurs don’t have anything to die -> they die too

Weeks without sun, temperature drops

Question 23

Greenhouse effect

Answer 23

Once dust settles, left in air was greenhouse gasses
Greenhouse effect
After winter -> much warmer than average temperatures

Question 24

Deccan Traps during impact

Answer 24

Volcanoes release CO2 into air -> reduce sunlight -> helped asteroid cover even more

Most likely happened before asteroid

Deccan traps most likely resting before impact

Question 25

What is the new hypothesis including the asteroid and volcanos?

Answer 25

Hypothesis: impact of asteroid affected the volcanoes and set it off but still controversial

Question 26

What survived?

Answer 26

Amphibians “cold blooded”

• Frogs
• Salamanders
• Caecilians

Reptiles “cold blooded”

• Snakes
• Crocodiles
• Lizards
• Turtles

Birds
many survived but some cretaceous did not

Mammals - sized sized
But extinct today

Question 27

What did NOT survive?

Answer 27

Dinosaurs
Non bird of dinosaurs
Feathered dinosaurs
Big marine reptiles
Pterosaurs

Question 28

Ichthyosaurs?

Answer 28

Ichthyosaurs extinct long before K/Pg boundary

Question 29

Ammonites and belemnites?

Answer 29

Amniotes are all descendants of the common ancestor between mammals and reptiles.
Ammonites and belemnites extinct during K/Pg mass extinction
Popular in cretaceous seas

Question 30

Generally, what is the trend between what survived and what didn’t?

Answer 30

Big species didn’t do well but some small species died too

No clear trend of who died and who didn’t

Question 31

Other mass extinctions

Answer 31

5 mass extinctions total through time
K/Pg most recent
End of Permian - THE WORST
95% of species DIED IN SEA

Question 32

Volcanism a factor in mass extinctions?

Answer 32

3 of time had volcanism associated with it
Volcanism most common mechanism

Probably had impact on end permian
b/c of the ET gas trapped in air but not well established

Question 33

What is the general trend in mass extinctions?

Answer 33

SIKE
Long term global warming was associated with P/T
Each mass extinction has unique set of potential causes

Bolide impact is well established only for K/Pg mass extinction

Global warming limited to K/Pg