End Permian Mass Extinctions Flashcards
What does the PME mark the end of?
The Palaeozoic
What is the difference between the Perm-Carb and the Permo-Triassic?
Carboniferous has presence of large ice sheet at southern pole
Permian Triassic is greenhouse warm (no ice sheet)
What is one of the unusual features of the carboniferous?
Major collapse of rainforests
What vegetation change occurred in the late Carboniferous?
From Lycopod-dominated assemblages to Fern-dominated
What did the Carboniferous rainforest collapse also impact?
Evolutionary history of tetrapod’s
What is an extinction?
The permanent end of an organism or group of organisms
What is extirpation?
Regional loss of organisms or groups (species, genera, families)
Not permanent
What are background extinction rates based upon?
exclusively on the fossil record
What is the background extinction rate?
2-5 marine families every million years
What are mass extinctions?
– widespread and rapid global decrease in diversity
– affects multiple groups of organisms
– observed across more than one setting or sedimentary facies
What are Lazarus taxa?
Taxa (species, genera, families) re-appearing post ‘extinction’
Extirpation not extinction
What are the types of extinction pattern?
Progressive
Catastrophic
Stepwise
What is progressive extinction?
extinction patterns relate to relatively long term, moderate intensity environmental change
What is catastrophic extinction?
Extinction patterns relate to a single, short term, high intensity environmental change exceeding the environmental tolerances of multiple species
What is stepwise extinction?
extinction pattern suggests biotic responses to short bursts of facies and/or environmental changes
What are the extinction events of the Permian called?
Mid-Capitanian
End Permian
What was the mortality rate associated with the Mid-Capitanian?
82% of fusilinid genera
87% brachiopod genera
25% of bivalve genera
24% of land plant species in S. China
56 of land plant species in N. China
What was the mortality rate associated with the end Permian?
96 % marine species
70% terrestrial vertebrate species
Only mass extinction to have affected insects
What is the name for a volume change in the ocean?
Eustatic change
What is the causes of the extinctions in the Permian thought to be?
Sea level
Global warming
Volcanism
Glaciation
What are the problems associated with changes in sea level?
Change in water depth, energy
levels, and position of wave bases.
Also effects changes in circulation
patterns
What happens as regression occurs?
The shelf (greatest diversity) progressively lost.
Low amount causes methane hydrate build which can be released when exposed
Erosion of former shelf and oxidation
Increased salinity
What are the environmental effects of transgression?
Sea level increases – larger volume, lowers salinity
Former shelf setting now under deeper water (palaeo-shelf)
Gas hydrates (*) may form, but narrower zone
Erosion concentrated above former
What is the relationship between warming and methane?
Warming directly leads to methane increase due to elevated wetland area productivity at mid-low latitudes +ve feedback loop
