EOSC 114 Lecture Notes - Eugene Merle Shoemaker, 298 Baptistina, Meteor Crater
8 Apr 2013
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Cretaceous paleogene quaternary: precambrian is 87% of earth"s history, the base of new geological time periods/groups of periods defined on the. Radiation of new species: what is a mass extinction event, at least 30% of species lost, broad range of ecosystems, short/sudden, how many mass extinctions? (at least 5 in the phanerozoic) Permo/triassic (largest extinction event: permits evolution of dinosaurs) Late ordovician: what causes mass extinctions, biologically-based: competition, predation, pathogens, physical earth-based! A) changes in continental configuration: changes in climate/ocean cyclicity/sea level. The greater the land mass the lower the biodiversity. Greenhouse / cold house effects: extraterrestrial-based, combination of many factors! Worst day for biosphere-permo/triassic 251 million years ago. Less than 1 million years duration: causes of the permo-triassic extinction, continental configuration- drop in diversity, sea level fall- less ocean ridge activity, oceanic stagnation- anoxia (absence of oxygen, possible extra terrestrial impacts, climate change. Siberian traps - massive volcanic activity: 2-3 million km3 basaltic lava.
