fortapocalypse sends word that a new paper was published today in the journal Science on the hypothesis that a comet impact wiped out the Clovis people 12,900 years ago. (We discussed this hypothesis last year when it was put forth.) The new evidence is a layer of nanodiamonds at locations all across North America, at a depth corresponding to 12,900 years ago, none earlier or later. The researchers hypothesize that the comet that initiated the Younger Dryas, reversing the warming from the previous ice age, fragmented and exploded in a continent-wide conflagration that produced a layer of diamond from carbon on the surface. While disputing the current hypothesis, NASA's David Morrison allows, "They may have discovered something absolutely marvelous and unexplained."