Earth Sciences 2240F/G Chapter Notes - Chapter 17: Background Extinction Rate, Holocene Extinction, Ordovician
16 Dec 2017
School
Department
Course
Professor
Document Summary
Unit 4: chapter #17: phanerozoic era - a trip through time. Phanerozoic era: 542 million years ago today (phanerozoic means abundant life: abundance of fossil evidence in the rock records. The mother of all catastrophes - the end of permian. Plate tectonics and life: rodinia in the latter part of precambrian began to come apart - supposedly triggering snowball earth. During the cambrian period water crept up on to the fragments of rodinia making shallow warm bodies of water where life exploded It is thought that at the end of the precambrian complex organism had developed and with new exposure to nutrients and warm waters these organisms thrived. With such rapid development it"s inevitable that the background extinction rate was high competition was intense what resulted was two distinct periods of mass extinction (542-488) Each extinction with 40% of marine genera (mass extinction of species not a part of the big 5)
