Mass Extinctions

Mass Extinctions - Mark Halma 622-14-1146 GLY 130 Mass...

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Mark Halma 622-14-1146 GLY 130 Mass Extinctions Many extinctions have occurred over the course of time but not many have been drastic enough to be considered mass extinctions. Some would argue that there have only been five major extinctions and other would say there has been up to twenty. According to David Raup and Jack Sepkoski, there have been five major extinctions large enough to be considered mass (wikopedia). The extinctions include End Ordovician, Late Devonian, End Permian, End Triassic, and End Cretaceous. The period after extinction is the recovery time period where we see an occurrence of Lazarus Taxa. The first of the major five mass extinctions occurred at the end of the Ordovician Period. Some believe that after finding more fossils from this time period that it was a minor event compared to the other major extinctions. The Ordovician extinction shows evidence of an extreme climate change (Sanelson, Tulane University). The first series of extinction occurred at the beginning of an ice age and the second series of extinction began as that ice age ended. The next extreme destruction of life came at the later part of the Devonian period. This extinction is assumed to have taken place in several different events at the Frasnian- Fammenian boundary. Evidence shows mass extinction of coral reefs and other associated species. Reports from China and Western Europe show iridium anomalies, shocked quartz, and glass spherules but there are also indications that major changes in
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Mass Extinctions - Mark Halma 622-14-1146 GLY 130 Mass...

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