As I wrote here, there has recently been a new theory proposed to account for the onset of the Younger Dryas, a 1,500 year long period of extreme cold that took place between about 13,000 and 11,500 years ago. The new theory suggests that an "impact event" occurred somewhere near the Great Lakes at the beginning of the Younger Dryas:
Iridium peaks, and spikes of ammonium and nitrate which could have been produced by extensive burning of biomass, are also found in the Greenland ice cores. The authors therefore propose that the black horizon is the result of massive forest fires raging across the whole North American continent, triggered by the fiery impact of a meteorite or comet - or possibly a low altitude explosion like the Tunguska event. Enough soot from the fires, and dust from the impact, would have been thrown into the atmosphere to significantly cool the climate, causing enough environmental stress to wipe out both the Clovis people and the mammoths.
Well, now the same team of scientists behind this theory have found further evidence for arctic impacts:
Startling evidence has been found which shows mammoth and other great beasts from the last ice age were blasted with material that came from space.
Eight tusks dating to some 35,000 years ago all show signs of having being peppered with meteorite fragments.
Basically, and as the picture above shows, it looks like the poor animals took something like a shot-gun blast to the upper surface (but NOT the lower surface) of the tusks.
Of course the dates--35,000 vs. 13,000 years ago--don't really match up, which leads geoscience consultant Allen West to speculate that
Maybe, these were tusks from dead animals that were just exposed on the surface, so when this thing blew up in the atmosphere, it would have peppered them. The date could really be anywhere from 13,000 to 35-40,000 years ago.
Plus an excellent post by Loren Coleman at Cryptomundo describing how cryptozoologists got to certain aspects of this theory years ago.