Are we in the midst of a mass extinction? Is Homo sapiens triggering this mass extinction? Four expert panelists have written responses to the aforementioned questions for this highly informative site.

This interactive module explores the environmental factors and species involved in five major mass extinctions.

This site from the American Institute of Biological Sciences contains articles on a wide array of issues related to species diversity and extinction. Many articles available in Spanish.

This is a very good introduction to the role evolution plays in the development of biodiversity. These topics and extinction are explained with the use of colorful interactive pictures.