It Took More Than an Asteroid to Kill Dinosaurs

One certainly cannot begrudge James Powell’s desire to sell his new book espousing his views of catastrophic dinosaur extinction (“Jurassic Park Ranger,” by Michael R. Forrest, So SoCal, July 12). But one is left with the impression that the impact of a meteorite (probably an asteroid) was the sole cause. For those scientists who have actually worked on the extinction, it is now clear that it was far more complex. The loss of vast seaways, prolonged massive volcanism and an asteroid impact now each appear to be necessary but separately insufficient causes for the extinction 65 million years ago.

J. David Archibald

Department of Biology

San Diego State University