CEE 1030 1nd Edition Lecture 25 Biodiversity and Extinction Outline of Last Lecture I Fossil record a Process of fossilization b Preservation potential c Enemies of preservation II Review III Modes of preservation IV Preservation of ecosystems Outline of Current Lecture I What is extinction II Biodiversity III Extinction continued Current Lecture I II III What is extinction a Extinction global die off of all individuals in a species b Extirpation local or regional disappearance of all individuals in a species due to die off or migration Biodiversity a 10 20 million species alive on Earth today b Only 10 have been described scientifically c Estimated 99 of all species that have ever lived on Earth are extinct d Typical life span of a species is 5 20 million years e Fossil based biodiversity estimates i Fossilization is rare very few organisms are fossilized ii Fossils are common 4000 million years of rare fossilization events add up iii Stratigraphic range interval between oldest fossil occurrence and youngest fossil occurrence of a species f Evolutionary rates i Origination and extinction rates of Phanerozoic marine animals ii Constant turnover of species over geologic time iii Rates higher during Cambrian Explosion Extinction continued These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute a Background extinction constant turnover of species over geologic time b Mass extinction event 70 extinction of global species diversity in a geologically short time c Big Five mass extinctions i Ordovician Silurian ii Late Devonian iii Permian Triassic iv Triassic Jurassic v Cretaceous Paleogene 1 Last of non avian disappearance of all land animals weighing more than 55 pounds 2 Extensive charcoal indicates widespread wildfires 3 Clay layer at Cretaceous Paleogene KT boundary contains high level of iridium which is abundant in meteorites 4 Shocked quartz a unique form of quartz crystal that has multiple fracture layers and is found only at impact craters and nuclear test sites 5 Tektites glassy spherules created when rock is vaporized by tremendous heat ejected and cooled rapidly 6 Effects of meteorite impact a Evidence of tsunamis suggest ocean impact b Meteorite impact of such magnitude would blast large amounts of dust into the atmosphere 7 Concurrent meteorite impact and volcanic eruptions resulted in extinction of about 70 of species
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