Mammoth Extinction

A new theory says that Mammoths and other large animals living 13,000 years ago may have been killed by a supernova. The theory suggests the supernova exploded about 41,000 years prior sending a shower of various sized iron particles across the galaxy. The article is very vague on how these particles caused the extinction but the scientist have found extensive evidence of these particles in dirt and bone samples from that period.

Firestone and West also uncovered evidence of an even earlier event that blasted parts of the Earth with iron-rich grains. Three mammoth tusks found in Alaska and Siberia, which were carbon-dated to be about 34,000 years old, are pitted with slightly radioactive, iron-rich impact sites caused by high-velocity grains. Because tusks are composed of dentine, which is a very hard material, these craters aren't easily formed. In fact, tests with shotgun pellets traveling 1,000 kilometers per hour produced no penetration in the tusks. Much higher energies are needed: x-ray analysis determined that the impact depths are consistent with grains traveling at speeds approaching 10,000 kilometers per second.

"This speed is the known rate of expansion of young supernova remnants," says Firestone.

Reading the above explanation it sounds like the extinctions were the result of everything being shredded by BBs from space. I don't think that's what they are suggesting but it makes for a scary new doomsday scenario.

Link: Supernova Explosion May Have Caused Mammoth Extinction