BILD 3 Chapter Notes - Chapter 9: Geologic Record, Antarctica, Eukaryote
30 May 2016
School
Department
Course
Professor
Document Summary
1. macroevolution: the sweeping changes in life as revealed by fossils a. i. Example: antartica used to be warm and teeming with tropical invertebrates/ dinosaurs. 1. the fossil record: sedimentary rocks are the richest source of fossils, strata a. i. Accumulated sedimentary rock layers b: many organisms did not die in the right place at the right time to be preserved as fossils, despite the limitations, fossil records are very detailed of biological change. 2. how rocks and fossils are dated: rock strata tell the relative age but the absolute age must use other techniques, radiometric dating a. i. a. ii. Rate of decay is expressed by the half-life a. i. 1. Time required for 50% of the parent isotope to decay: when organisms die, their carbon-12 amount does not change while the radioactive carbon-14 decays. Find the ratio of the two to calculate the age. A standard time scale that divides earth"s history into four eons and further subdivisions a. i. 1.
