Lecture 18 Flashcards
Background rate of extinction
Over millions of years, an average number of taxonomic families will go extinct
Chronospecies
A single species, changing morphologically, genetically, or ecologically over a long time scale
Mass extinction
Extinction of a large number of unrelated species (biodiversity loss) over a short period of geological time
End Ordovician
Loss of 49% of animals, marine organisms suffered most
Great Ordovician Biodiversity Event
Diversification of species within those body forms
Late Devonian
Species in shallow waters impacted most, extinction pulses
End Permian
The great dying: 70% terrestrial vertebrates and 96% marine species
-mass volcanic eruptions
End Triassic
76% of species went extinct
End Cretaceous
75% of plant and animal species went extinct, followed by the rise of mammals
Devonian Plant Hypothesis
Large numbers of plants led to global cooling and anoxic ocean environments (lack of oxygen)
Dead zones
Regions of low oxygen in waterways
Impact hypothesis
End cretaceous extinction caused by bolide impact, bolide threw a cloud of particles into the atmosphere
Deccan traps
Massive basalt floods, likely produced many of the same effects seen during the extreme volcanism of preceding mass extinctions
Press-pulse hypothesis
Where 2 events occur: the first stresses an environment then the second occurs as a result of stressed cause by first (second event has greater than expected impact on the environment)
