Yesterday we talked about the discovery of amino acids in meteorites. And then today comes news that there was an explosion of life (pardon the pun) after meteorites rained down more than 400 million years ago. Even though the Earth was struck by more than 100 1-km meteorites in a short period of time, life not only survived, it thrived.
The string of impacts occurred during the Ordovician period, between 490-440 million years ago. It wasn’t quite life as we know it, but creatures were living on land, and organisms had evolved to fit every niche in the oceans.
According to planetary scientists, a disruption in the asteroid belt about 470 million years ago sent hundreds of space rocks out of their normal orbit, and into ours.
Over a few million years, more than 100 separate meteorites larger than 1 km across struck the Earth, throwing up a Sun-clogging shroud of dust. Plants, starved for sunlight, died, and the chains of life depending on them collapsed.
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But incredibly, life thrived after this period, evolving into new and interesting life forms.
Researchers from the University of Copenhagen and Lund University gathered together chemical samples from meteorites, fossils, and examined several craters in Sweden. The Lockne crater, for example, is located in northern Sweden and has a diameter of 7.5 km across.
They found evidence for the thriving life forms in layers newer than the ones containing debris from the meteorite strikes.
“You could say that biological evolution experienced a serious boost within a relatively short period of time. And, as is the case with, for example, volcanic eruptions or large forest fires, the impacts initially had a devastating effect on all life, but from the ashes arose a much richer fauna than had existed previously,” said Dave Harper from the University of Copenhagen.
This is research we’ve seen before. Paleontologists announced earlier this year that life can bounce back quickly from an extinction event, but it takes a long time for the true diversity of life to reappear. So, after most life is wiped out by an asteroid, the cockroaches and rats take over. You might have the same number of creatures, but it takes many years before you get rich ecosystems with butterflies and giraffes too.
Original Source: Nature Geoscience