BIOL 2P05 Lecture Notes - Lecture 24: Megafauna, Mastodon, Habitat Fragmentation
14 Mar 2018
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Mammoths and mastadons were known from fossil remains. Thomas jefferson disagreed, believed in a completeness of nature whose inherent balance did not allow species to go extinct naturally. Lewis & clark - went to look for these species. Along with mastodon, there were many other mega-fauna - huge animals. By 10,000 years ago, 2/3 had gone extinct. Direct indirect (changing food chain - killing smaller animals so less food for larger animals) Chemicals build up in bones as they fossilize. Over the course of history, the magnetic polarity of the earth has flipped on numerous occasions. Burrowing animals can push fossils up through the layers. Forward smearing: dating an extinction later than it occured. Backward smearing: dating an extinction earlier than it occured. Last fossilized remains will probably not be the actual last survivor. If you sum up all of the extinctions --> 95% are not associated with mass extinction.
