Slashdot linked up the latest in "can't-see-it-coming" apocalypses, gamma ray bursts:
In the latest issue of the Astrophysical Journal Letters, scientists argue that a gamma ray burst, the most powerful explosion that occurs in the universe, was responsible for the Ordovican mass extinction in which 60% of all marine invertebrates died.
Unfortunately the article doesn't reveal what sort of evidence these scientists are relying on. Unlike BFRs* falling from the sky, gamma rays don't leave trace evidence of exotic minerals scattered all over the planet. Even better, since they travel at the speed of light there's no way to detect a gamma ray burst on the way. This may change if we ever figure out where the dratted things come from (right now we have no idea), but until then if it's gonna get us, it's gonna get us.
Ain't the universe grand?