Might the Mother of All Mass Extinctions have been caused by an asteroid impact? Not exactly a new idea, but there's some more chatter about it in this week's Science magazine. This BBC News article provides a brief summary, if you've neither the means nor the inclination to read the article in Science. Personally, I prefer to blame the Permian-Triassic extinction on the formation of Pangea. But I'm a world-class ignoramus.