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ERTH 2401 (36)


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Earth Sciences
ERTH 2401
Claudia Schroder- Adams

Lecture 19 Extinctions Definitionthe birth rate of an organism does not keep up with the death rate Cause of extinctionNature of extinctionBackground Extinction are happening all the time and a very large part of dinosaurs are becoming extinct due to background extinctionCauses of background Extinctioncompetition for food sourcespace destruction of habitat through fire river migration drying wetland eruption of volcanoes Changes in climate development of mountain ranges Ex Rhino Less dramatic than mass extinctionSlower speed over longer timeML Mckinney suggested 95 of all extinction are accounted for by background extinctions Many dinosaurs have been victims to background extinction Mass extinction Large numbers of species go extinct many types of species go extinct Effect must take place on a global scale Happens over a short period of geological time Times of Mass extinctionKNOW VERY IMPORTANT Late Ordovician 438 MaLate devonian 380 MaPermian 245 Ma largest mass extinction 96 of all species Late Triassic 208 Ma Cretaceous Tertiary65 Ma Manicouagan Extinction Permian Extinction Most severe mass extinction 96 of all species died52 of all families Over 2 Mill years Sea level drop Why is it difficult to study the permian extinction you can only go by what it was preserved permian had Pangea so much was exposed as land permian sea floor would it be preserved in modern oceanno floors are constantly being sub ducted Reduced amount of shelf space Triassic Extinction Crater in QuebecStudy of extinctionsproblemsIncompleteness of fossil record
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