extinctions Flashcards
what are the big 5 mass extinctions?
- end Ordovician
- late Devonian
- end Permian
- end Triassic
- end Cretaceous
what are the causes of mass extinction?
- ET impact
- volcanoes
- global cc
- ocean anoxia and acidification
what was there in the end Permian mass extinction?
61%
on land: mutagenesis of plants, forests lost 5 Myr, replaced by free-sporing lycopsids, erosion
what volcanic event happened in the end Permian?
- Siberian traps
- spewed out 2 mil Km3 of lava covering 1.6 mil km2 to a depth of 3000m
what happens in carbon cycle perturbation?
- volcanic eruptions release CO2 and lavas intruded into coal beds igniting them and releasing more CO2
what is ocean acidification?
when large amounts of CO2 are added to the atm and dissolve in the surface ocean which acidifies it
when CO2 is added to the atm and dissolves in the ocean what does this inhibit?
the formation of CaCO3 shells
how does the ocean become anoxic?
decreases in O2 demand due to increased P in O2 supply which reduces O2 stability
what happens after ocean anoxia?
it took 10 mil years for complex ecosystems to recover and 100 mil years for biodiversity to recover to pre-extinction levels
what happened in the end Cretaceous mass extinction?
- 60% became extinct
- dinosaurs extinct
- those who could shelter in water or who had larvae eggs underground survived
what eruptions happened in the end Cretaceous?
- Deccan traps
what is the ‘strange love’ ocean?
ocean photosynthesis was wiped out
marine phytoplankton suffered
90% species loss only 12 species survived
what happened when the biological pump collapsed at the end of Cretaceous?
- drop in surface temp 13°C
- CaO in ocean floor sediments drops from 40-60% to less than 10%
what does the biological pump do?
takes up CO2 from the atm and transfers it to the deep ocean
consequences of extinction
origination rates increase after extinctions as empty ecological niches are filled
mammals diversify, rapidly increasing in size and filling niches vacated by dinosaurs
