Mass Extinction Events: Causes and Effects
Mass Extinction Events: The Causes And Effects
Kieran A. F. Burley
A mass extinction is defined as an event when there is a massive decrease in the abundance and diversity of all species on the planet, this will occur over a relatively short period of time, for any one species an extinction is catastrophic. Extinction events occur continually this results in regular change of all species on the planet and is known as background extinctions, sometimes however extinction rates rise suddenly for a relatively short time and this is a mass extinction.
Mass extinctions that have occurred through time.
There have been a number of examples the most famous being the Cretaceous-Tertiary mass extinction or K-T extinction, this is because the dinosaurs became extinct during this particular mass extinction. This is also the most recent large scale mass extinction and has been relatively well documented in the rock strata. (Jablonski D., 2001)
A number of mass extinction events have occurred throughout geological time. There have been five major mass extinctions, they are the following...
the Ordovician-Silurian boundary Late Devonian The Permo-Triassic boundary The Triassic-Jurassic boundary And the Cretaceous-Tertiary boundary
All of the extinctions mentioned above have in some way affected well-established genera. Extinction event | Time | Organisms most affected | Cretaceous-Tertiary | 65 Ma | Bivalves, Belemnites, dinosaurs, Ammonites, pterosaurs, plesiosaurs, mososaurs, numerous families of fish and many others all became extinct at this time. | Triassic-Jurassic | 200 Ma | Sea and land animals. Many Ammonoids. About 35% of all animal families die out. Most of the dinosaur families become extinction. | Permo-Triassic | 251 Ma | 95% of all marine species. In particular Brachiopods, Corals, Ammonoids, Echinoids and Trilobites. 50% of all animal families. Many tree and plant organisms
Kieran A. F. Burley
A mass extinction is defined as an event when there is a massive decrease in the abundance and diversity of all species on the planet, this will occur over a relatively short period of time, for any one species an extinction is catastrophic. Extinction events occur continually this results in regular change of all species on the planet and is known as background extinctions, sometimes however extinction rates rise suddenly for a relatively short time and this is a mass extinction.
Mass extinctions that have occurred through time.
There have been a number of examples the most famous being the Cretaceous-Tertiary mass extinction or K-T extinction, this is because the dinosaurs became extinct during this particular mass extinction. This is also the most recent large scale mass extinction and has been relatively well documented in the rock strata. (Jablonski D., 2001)
A number of mass extinction events have occurred throughout geological time. There have been five major mass extinctions, they are the following...
the Ordovician-Silurian boundary Late Devonian The Permo-Triassic boundary The Triassic-Jurassic boundary And the Cretaceous-Tertiary boundary
All of the extinctions mentioned above have in some way affected well-established genera. Extinction event | Time | Organisms most affected | Cretaceous-Tertiary | 65 Ma | Bivalves, Belemnites, dinosaurs, Ammonites, pterosaurs, plesiosaurs, mososaurs, numerous families of fish and many others all became extinct at this time. | Triassic-Jurassic | 200 Ma | Sea and land animals. Many Ammonoids. About 35% of all animal families die out. Most of the dinosaur families become extinction. | Permo-Triassic | 251 Ma | 95% of all marine species. In particular Brachiopods, Corals, Ammonoids, Echinoids and Trilobites. 50% of all animal families. Many tree and plant organisms
References: Berner R. A., 2002. Examination of hypotheses for the Permo–Triassic boundary extinction by carbon cycle modelling.Hallam A. & Wignal P. B., 1997. Mass Extinctions and their aftermath. Jablonski D., 2001. Lessons from the past: Evolutionary impacts of mass extinctions. McGee Kenneth A.,Doukas Michael P., Kessler Richard, and Terrence M. Gerlach 1997. Impacts of Volcanic Gases on Climate, the Environment, and People. U.S. Geological Survey Open-File Report 97-262 Wignall P.B., 2000. Large igneous provinces and mass extinctions. Earth-Science Reviews. 1177.