Chapter 3: The Great Extinctions

Red dot at each major extinction: Ordovician (440 myb) Marine family numbers Red dot at each major extinction: Ordovician (440 myb) Devonian (365 myb) Permian (245 myb) Triassic (210 myb) Cretaceous (66 myb)   Data from Sepkoski.  Graphs after Sole & Newman. http://exobio.ucsd.edu/Space_Sciences/extinctions.htm

Extinction Event. Years Before Present (millions). Families Lost Extinction Event Years Before Present (millions) Families Lost Recovery Time (millions years) Cretaceous-Tertiary 66 15% of 650 20 Triassic 213 20% of 300 ** Permian 250 30% of 400 100 Devonian 360 22% of 450 30 Ordovician 440 22% of 450 25

http://www.uky.edu/KGS/coal/webgeoky/kygeolgy.htm

http://www.bbc.co.uk/education/darwin/exfiles/index.htm

Theories of Extinction http://www.enchantedlearning.com/subjects/dinosaurs/extinction/Other.html

Location of the Chicxulub crater (circle) on Mexico's Yucatan Peninsula. http://www.icr.org/pubs/imp/imp-334.htm

http://www.tulane.edu/%7Esanelson/geol204/impacts.htm

2 million years ago 630,000 years ago 1980 http://www.icr.org/pubs/imp/imp-302.htm, http://freerepublic.com/focus/f-news/1050165/posts?page=353

http://www.ucmp.berkeley.edu/geology/tectonics.html

The jigsaw fit of Africa and South America shows rocks of equivalent age matching when the continents are reassembled. http://www.geology.ohio-state.edu/~vonfrese/gs100/lect25/

http://faculty.plattsburgh.edu/thomas.wolosz/somedefinitions.htm

v Figure 1 The fossil record of marine animal biodiversity. Standing diversity of genera and families through the Phanerozoic ( a), and corresponding percentages of extinction (b) and origination (c) of genera in each stratigraphic interval. Shaded bands highlight recovery intervals (between extinction rate peaks and subsequent origination rate peaks) for the 'Big Five' mass extinctions: end-Ordovician (1), late Devonian (2), end-Permian (3), end-Triassic (4) and Cretaceous–Tertiary (5). Dotted lines in b and c show the long-term trends (estimated using LOWESS, a robust curve-fitting technique19) that are subtracted from extinction and origination time series before calculating cross-correlations. http://www.nature.com/nature/journal/v404/n6774/fig_tab/404177a0_F1.html

The Cyclical Nature of Extinction Events It has been suggested that mass extinction events occur in a roughly cyclical manner--that is, about every 26 million years.  The following graph is a product of a 1984 study by Raup and Sepkoski and shows clearly that major extinction events seem to be quite regularly distributed over time. http://www.earth.rochester.edu/ees207/Mass_Ext/higgins_mass2.html

Solé, R. V. , Montoya, J. M. and Erwin, D. H. 2002 Solé, R. V., Montoya, J. M. and Erwin, D. H.. 2002. Recovery after mass extinction: evolutionary assembly in large-scale biosphere dynamics. -Philos. Trans. R. Soc. B 357: 697-707.

Sepkoski, J. J. 1997. Biodiversity; past, present, and future Sepkoski, J. J.  1997.  Biodiversity; past, present, and future.  Journal of Paleontology, July 1997, Vol. 71, Issue 4, pp. 533-539 

Patterns of extinction and biodiversity in the fossil record, R. V Patterns of extinction and biodiversity in the fossil record, R. V. Sole and M. E. J. Newman, in the Encyclopedia of Global Environmental Change, T. Munn (ed.), John Wiley, New York (2001).

Climate change threatens new wave of extinction http://www.birdlife.net/news/news/2004/01/climate_change.html http://www.eurekalert.org/pub_releases/2004-01/ci-ccm010504.php