Extinct, extinct in the wild, believed to be extinct.
These websites will help you research extinct animals. Remember,
you must select an animal that has become extinct within the last
thirty million years. Therefore, you may not select a dinosaur.
http://www.50birds.com/extan/gextanimals1.htm
http://www.extinctanimal.com/
http://www.nature.ca/NOTEBOOKS/ENGLISH/enexpg.htm
http://extinctanimals.petermaas.nl/
http://en.wikipedia.org/wiki/List_of_extinct_animals
http://eelink.net/EndSpp.old.bak/ES.lists.html
http://bagheera.com/inthewild/extinct.htm
http://www.earthwitness.com/Animals.htm
Geological timeline:
http://en.wikipedia.org/wiki/Geologic_timescale
http://www.enchantedlearning.com/subjects/Geologictime.html
http://www.ucmp.berkeley.edu/help/timeform.html