Extinction

Animal Extinctions in the Fossil Record: A Developmental Paradigm
Article by Vaclav Petr discussing the possible causes of extinctions.
http://www.mprinstitute.org/vaclav/Develop.htm

Extinction
A number of extinction concepts are discussed and loosely defined, followed by a survey of some important extinction and "extinction-like" events, primarily from the Phanerozoic.
http://www.peripatus.gen.nz/paleontology/extinction.html

Extinctions: Cycles of Life and Death Through Time
Covers patterns and periodicity of extinction, with discussions of major mass extinctions and minor extinction events.
http://park.org/Canada/Museum/extinction/homepg.html

The Late Devonian Mass Extinction
A professional technical paper discussing whether the Late Devonian (Frasnian-Famennian) mass extinction was initiated by an extraterrestrial impact or an earth-bound event. [PDF]
http://www.lpi.usra.edu/meetings/impact2000/pdf/3072.pdf

Mass Extinction
A mathematical model for mass extinction.
http://www.lassp.cornell.edu/newmme/science/extinction.html

Our Nemesis?
Article on a paper by David Raup and John Sepkoski, two respected paleontologists, making the remarkable claim that great catastrophes occur on the Earth every 26 million years,
http://www.thekeyboard.org.uk/Our%20Nemesis.htm