To Quetzel or anyone else interested in ice age extinctions:
I honestly do not mean to thread hijack, but I wanted to post one more interesting thing about the ice ages (the Ordivician in particular), and a possible explanation to mass extinction. A recent article in my local newspaper outlined some research done at my beloved alma mater:
News, Sports, Jobs - Lawrence Journal-World: news, information, headlines and events in Lawrence, Kansas
Here's a more detailed description of the research:
System Unavailable
Never even knew anything about gamma-ray bursts being a possibility.
Apologies for steering off-road. Back on the micro/macro topic.