EXTINCTION: “THE GREAT DYING” (4/23

Question 1

When were therapsids the dominant land animals? (Late Permian thru Middle Triassic)

Answer 1

○ Were the dominant vertebrate fauna during the Triassic period

Question 2

How do stable carbon isotope ratios (13C/12C) change during the “Great Dying”?

Answer 2

○ Major decrease

Question 3

What does this signify?

Answer 3

• What does this signify?
○ Signifies release of 13C-depleted carbon into the atmosphere
○ Sharp rise of CO2 in the atmosphere

Question 4

How do carbon isotope ratios (13C/12C) during the PTB mass extinction differ from those of the preceding Carboniferous?

Answer 4

• carboniferous–coal was so buried during the time: Created increase in C13/C12 ratio bc burial depleted coal/org carbon so much in atm and ocean system
  
  • PTM–release of mass amounts of CO2 into the air and quickly. raised the amount of inorganic carbon in the atm/ocean system quickly which increased ph

Question 5

Great Dying “kill mechanism”

Answer 5

• Great Dying “kill mechanism” => Siberian Traps (large igneous province with extrusion of massive amounts of lava)

Question 6

Thermal combustion of Carboniferous coal via intrusion of Siberian Traps

Answer 6

LIPs - large igneous provinces

Question 7

Exaptation: evolution of jaw bones

Answer 7

Exaptation: evolution of jaw bones into ear bones during reptile-to-mammal transition (modification of pre-existing structures to serve a new function)

Question 8

Morganucodonts (Late Triassic):

Answer 8

• Morganucodonts (Late Triassic): earliest true mammals, diminutive shrew-sized mammals

Question 9

When were dinosaurs (diapsids) the dominant land animals?

Answer 9

○ Most of the Mesozoic Era: Late Triassic thru Cretaceous)

Question 10

In general, what did the earliest dinosaurs look like?

Answer 10

• In general, what did the earliest dinosaurs look like?
○ Eoraptor: earliest and most primitive dinosaur
○ A lot of them were bipedal

Question 11

How are dinosaurs distinguished from other reptiles?

Answer 11

• How are dinosaurs distinguished from other reptiles?
○ Advanced mesotarsal joint- the main foot hinge is positioned between the first and second row of ankle bones
○ Ankle bones are fused to the shin
○ Astragalus larger than calcanem

Question 12

Pterosaurs =>

Answer 12

• Pterosaurs => ankle bones, advanced mesotarsal joint => first appear during Triassic Period

Question 13

Evolution of Flight =>

Answer 13

• Evolution of Flight => convergent evolution in wings of pterosaurs, bats, and birds- super long pinky finger (4th digit) in Pterosaur wings