ERTH 2401 Study Guide - Seafloor Spreading, Biostratigraphy, Blast Wave
Document Summary
Definitiion of extinction: the birth rate of an organism does not keep up with ththe death rate. Mass extinction vs. background extinction: background : less dramatic, slower over time. Times of mass extinctions: late ordovician, late devonian (corals, permian - deadliest (almost whipped out all life, late triassic, cretaceous/tertiary. Permian extinction: 96% of all species died, 56% of all families died, took place over 2 million years, glaciation event creating a sl drop. Land dried out: large volcanic eruptions - ash deposits found in siberia and arctic. Problems with studying extinctions: incomplete fossil record and sedimentary record, most complete information in marine record (not a lot of info with dinosaurs) Time resolution preserved: 50-90% of rock record not preserves. 9 out of 10 hours of earth history not: only 20 localities of kt boundary mass destinction. Paleontological resolution: mckinny: 5-50 mill. species extinct today. Less that 1% fossilized: importance of lagerstaetten, first appearance datum - when species first appears.
