Virginia Tech
Virginia Polytechnic Institute: Greenhouse Dinosaur Extinction Theory
This comprehensive page discusses the Asteroid Impact vs. Volcano-Greenhouse dinosaur extinction debate. It was written by paleontologist, professor, and scientist Dr. Dewey McLean.
Other
Mbari: Marine Flora
For good information about marine flora, go to this site from the Monterey Bay Aquarium Research Institute. It provides details about different types of seaweeds and phytoplankton. It also contains a photo gallery.