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13 Cards in this Set
- Front
- Back
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What is the definition of extinction?
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The death of a taxon (any of the levels of the classification scheme of living thing).
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Why is the fossil record sometimes wrong about extinctions?
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Pin-pointing the exact time of extinction in the fossil record is very difficult. It is impossible to prove when something is not there. The last appearance of an animal does not equal the time of extinction in the fossil record.
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What did Signor and Lipps have to say in 1982?
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They said that gas in the fossil recod can make the severity of an extinction seem less. The effect is an inaccurate picture of actual extinction times.
--mass extinction are worse than they seem in the fossil record. |
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What did Mr. Lazarus discover?
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When a species seems to go extinct (disappear from the fossil record) but they show up later in younger rocks, or older rocks. it's the result of poor fossil record in on time horizon, and/or the species left the area to go to a "refuge."
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What is a pseudo-extinction?
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--a subdivision of an evolving lineage. It is two brand new species, nothing has died out.
-- Larger groups of animal and one part of the group goes extinct |
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What did Sepkoski do in 1981?
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He wrote the first detailed descriptions of diversity and extinctions in the Phanerozoic. Worked mostly on the Family level.
-- he noted trends in marine families Vs. time, like... *steep increase from Cambrian through Ordovician *The diversity peak in Ordovician (Permian plateau) *Rapid decline at permian/triassic boundary *After than, steady increase at 2X permian plateau |
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What is a background extinction rate?
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Not related to a catastrophe event. They happen every day.
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What is an extinction rate?
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Number of taxa that go extinct in a given amount of time.
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What are the five times of increased extinction?
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Tem,Ashg,Guad ( see slide)
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What did Sepkoski find to be the periodicity of the increased extinction pattern?
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Every 26-30 Ma. During the past 250 Ma. This is fairly regular. Missing 2 out of the ten.
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What happened statistically during the times of increased extinctions?
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Decrease in background extinction rates
Average rate intensity decreased from Cambrian until now. Benton Taxa are more resistant to extinction over time?? Samplimg Artifact?? Tax anomic structure?? (the way we classify animals). Fewer species in the genus at the beginning, so if later the genus has more species then it is less likely that the entire genus will die out. |
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What were Raup and Sepkoski's findings in 1982?
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There are 5 times of increased extinction intensity in marine animal families. At the end of Ordovician, Devonian, Permian, Triassic, and Cretaceous.
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What do the terrestrial and insect fossils show about increased extinction periods?
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Terrestrial vertebrates show that there was impact during the permian, Triassic and Cretaceous.
Insects were impacted in the Permian and less in the Crestaceous. |
