Good visual site from PBS that presents the geologic history of sharks and acts a good introduction.

This site contains on-line exhibits including animals, plants, time periods, phylogeny, geology, and evolution. Also, a search is provided at the bottom of the site for more specific information.

Standford University provides interesting biographical and professional information on Stephen Jay Gould and his many contributions to scientific thought, including his efforts to help people see science "As something that is important...