1. David Raup and Jack Sepkoski analyzed patterns of extinctions large enough to qualify as "mass extinctions." List the six events they found from earliest to latest, and plot them (from Fig. 6-1) onto Figs. 5-12 to 5-14.
2. What are some generalities you can make about these six mass extinction events and their eventual recovery? What are Lazarus taxa? What is the most likely explanation of their absence from the fossil record for a period after an extinction event?
3. (SKIP Spring, 2003) What are some physical global phenomena that might explain mass extinction events? For each of these six events, list the presently favored explanation (if any) that is best supported by current evidence.
4. Which is the "Mother of Mass Extinctions" and why? What might this have to do with "plume tectonics" and Siberian Traps? Why is an alternative hypothesis called "Murder on the Orient Express"? What other major factors might help account for this giant extinction event, including models by Yukio Isozaki, Andrew Knoll, and Greg Retallack?
5. (SKIP Spring, 2003) What was the supposed connection between periodic extinctions and Nemesis, the Death Star? According to Cowen, what is a more likely explanation for the patterns observed?
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