Here’s an interesting new theory–the large mammals of America may have been wiped out by a storm from a supernova:

Richard Firestone, a nuclear scientist at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory, who formulated the theory with geologist Allen West, told Discovery News that a key piece of evidence for the supernova is a set of 34,000-year-old mammoth tusks riddled with tiny craters.

The researchers believe that in the sequence of events following the supernova, first, the iron-rich grains emitted from the explosion shot into the tusks. Whatever caused the craters had to have been traveling around 6,214 miles per second, and no other natural phenomenon explains the damage, they said.

Interesting, and as the article says, it’s testable. If it’s true, it’s a new kind of threat to worry about. I wonder if there would be any warning?

I don’t think that the precision in that paragraph makes sense, though–“around 6,214 miles per second”?