Visit the Smithsonian Institution Paleobiology Dept. website (linked to the BIOL 471 website), then to the featured webpages on dinosaurs.  Then be prepared to answer the following questions concerning the phylogeny, biology and extinction of dinosaurs.

1.(2) What is a dinosaur? In what geologic period did dinosaurs first appear?

2.(2) What are archosaurs? What groups besides dinosaurs are derived from archosaurs?

3.(2) What is the present number of recognized Mesozoic dinosaur species?

4.(2) What is the difference between ornithischian and saurischian dinosaurs?

5.(2) What is the Alvarez theory for the extinction event at the end of the Cretaceous? What other theories have been proposed?