Extinction: The Great Dying Flashcards
When were therapsids the dominant land animals?
- Triassic Period
How do stable isotope ratios (13C/12C) change during the “Great Dying”?
major decrease
How do carbon isotope ratios (13C/12C) during the Great Dying (PTB Mass Extinction) differ from those of the preceding carboniferous?
Carboniferous: coal was buried which created an increase in C13/C12 ratio because the organic matter buried and turned to coal took much of the C12 with it
PTB: released MASS amounts of of CO2 to the air which causes a drop in the ratio of 13C/12C ratio due to excessive release
Great Dying “Kill Mechanism”
Siberian Traps (large igneous province with extrusion of massive amounts of lava that released hella carbon when burning buried coal)
How would a sharp rise in atmospheric CO2 levels affect surface-ocean pH?
- lowers the pH of the sea water
What is pH?
a figure expressing the acidity or alkalinity of a solution on a logarithmic scale on which 7 is neutral, lower values are more acid, and higher values more alkaline.
(-log10C)
Therapsids
- mammal like reptiles of the Permian and Triassic period
- ruled after the Great Dying
Exaptation
“natural selection ‘tinkering’”
- modification of preexisting structures to serve a new function
I.E. evolution of jaw bones into ear bones during the reptile-to-mammal transitions
Morganucodonts
- earliest true mammals
- shrew sized
- possessed both dentary/squamosal jaw hinge and an incus and malleus in the middle ear
When were dinosaurs (diapsids) the dominant land animals?
most of the mesozoic era, late triassic through the cretaceous
How are dinosaurs distinguished from other reptiles?
- advance metatarsal joint
- ankle bones are fused to the shin
- astragalus larger than calcanem
Evolution of Flight
convergent evolution in wings of pterosaurs, bats, and birds
Pterosaurs
first appear in the triassic period
- advance mesotarsal joint, ankle bones
