Eight tusks dating to some 35,000 years ago all show signs of having being peppered with meteorite fragments. The ancient remains come from Alaska, but researchers also have a Siberian bison skull with the same pockmarks.
The scientists released details of the discovery at a meeting of the American Geophysical Union in San Francisco, US. They painted a picture of a calamitous event over North America that may have severely knocked back the populations of some species.
"We think that there was probably an impact which exploded in the air that sent these particles flying into the animals," said Richard Firestone from the Lawrence Berkeley National Laboratory. "In the case of the bison, we know that it survived the impact because there's new bone growth around these marks."
And geoscience consultant Allen West added: "If the particles had gone through the skin, they may not have made it through to vital organs; but this material could certainly have blinded the animals and severely injured them."
Raised, burnt surface rings trace the point of entry of high-velocity projectiles; and the punctures are on only one side, consistent with a blast coming from a single direction.
The ratios of different types of atoms in the fragments meant it was most unlikely they had originated on Earth, the team told the AGU meeting.
The researchers reported the discovery of sediment at more than 20 sites across North America that contained exotic materials: tiny spheres of glass and carbon, ultra-small specks of diamond and amounts of the rare element iridium that were too high to be terrestrial. The scientists also found a black layer which, they argued, was the charcoal deposited by wildfires that swept the continent after the space object smashed into the Earth's atmosphere.
This is awesome -- I always assumed that any kind of space bombardment would be in the "nuclear holocaust" range, you know, instant flaming death from above. I didn't expect to hear about mammoths with uncomfortably-warm space acne.
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