1. Summarize, in your own words, what the leading hypotheses for dinosaur extinction prior to Alvarez’s research. How do you think his team’s hypothesis was received by the scientific community at the time (1980)?
2. Why is the presence of iridium in the sediment samples key to the meteorite hypothesis?
3. Why was it important to show iridium levels in three different regions (Italy, Denmark, and New Zealand)? Why wouldn’t one sample location be enough? And why would the New Zealand sample be especially important after finding the two samples in Europe?
4. What are the “expected biological consequences” of “suppressing photosynthesis” on a world-wide level?
5. Summarize, in your own words, the “major obstacle” researchers encountered when attempting to discover the cause of the extinction.
6. In paragraph 6 (page 38) the article provides a summary of the work of other researchers with regard s to the study of platinum metals in deep-sea sediments. Why do the authors bother to do this?
7. If a large meteorite killed off so many species, how did mammals and other animals survive?
8. Why does the article discuss the eruption of Krakatoa? How can a volcanic eruption support their meteorite hypothesis?