CEE 1030 1nd Edition Lecture 25: Biodiversity and ExtinctionOutline of Last Lecture I. Fossil recorda. Process of fossilizationb. Preservation potentialc. Enemies of preservationII. ReviewIII. Modes of preservationIV. Preservation of ecosystemsOutline of Current Lecture I. What is extinction?II. BiodiversityIII. Extinction, continuedCurrent LectureI. What is extinction?a. Extinction: global die-off of all individuals in a speciesb. Extirpation: local or regional disappearance of all individuals in a species due to die-off or migrationII. Biodiversitya. 10-20 million species alive on Earth todayb. Only 10% have been described scientificallyc. Estimated 99% of all species that have ever lived on Earth are extinctd. Typical life-span of a species is 5-20 million yearse. Fossil-based biodiversity estimatesi. 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 speciesf. Evolutionary ratesi. Origination and extinction rates of Phanerozoic marine animalsii. Constant turnover of species over geologic timeiii. Rates higher during Cambrian ExplosionIII. Extinction, continuedThese 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 timeb. Mass extinction event: >70% extinction of global species diversity in a geologically short timec. “Big Five” mass extinctionsi. Ordovician/Silurianii. Late Devonianiii. Permian/Triassiciv. Triassic/Jurassicv. Cretaceous/Paleogene1. Last of non-avian disappearance of all land animals weighing morethan 55 pounds2. Extensive charcoal indicates widespread wildfires3. Clay layer at Cretaceous/Paleogene (KT) boundary contains high level of iridium, which is abundant in meteorites4. Shocked quartz: a unique form of quartz crystal that has multiple fracture layers and is found only at impact craters and nuclear testsites5. Tektites: glassy spherules created when rock is vaporized by tremendous heat, ejected, and cooled rapidly6. Effects of meteorite impacta. Evidence of tsunamis suggest ocean impactb. Meteorite impact of such magnitude would blast large amounts of dust into the atmosphere7. Concurrent meteorite impact and volcanic eruptions resulted in extinction of about 70% of
View Full Document
Unlocking...