Credit: Wikipedia Commons
Once upon a time, the prehistoric steppes of North America hosted a menagerie of giant mammals — woolly mammoths, saber-toothed tigers, cave bears, camels, horses, lions, giant ground sloths as well as bison, moose, musk-oxen and even spear-chucking humans dressed in fur.
As any video-watching child knows well, the late centuries of the ice age fairly rocked with these immense beasts and their furry companions.
And then, about 13,000 years ago, most of this fabulous megafauna rapidly died out. Mammoths went extinct. Lions and tigers and horses and sloths disappeared. Scientists have long debated the causes.
Was it overhunting by Pleistocene humans with spears, wild fire and shrewd killing strategies? Or was it a sudden shift in the climate that destroyed the productive grassy steppe that supported this network of grazers and their predators?
Now, an international team of scientists led by Richard Firestone of Lawrence Berkeley National Laboratory has uncovered evidence that an immense explosion — accompanied by a nuclear-strength shockwave — triggered a catastrophic climate shift that wiped out life across America. The work follows up on earlier findings by Firestone that a supernova 41,000 years ago may have created a killer space rock and sent it tumbling into the home planet.
In other words, just like the dinosaurs before them, the mammoths may have been fried by an asteroid.