Double space strike 'caused dinosaur extinction'
The dinosaurs were wiped out 65 million years ago by at least two space impacts, rather than a single strike, a new study suggests.
Previously, scientists had identified a huge impact crater in the Gulf of Mexico as the event that spelled doom for the dinosaurs.
Now evidence for a second impact in Ukraine has been uncovered.
This raises the possibility that the Earth may have been bombarded by a whole shower of space rocks.
The new findings are published in the journal Geology by a team lead by Professor David Jolley of Aberdeen University, UK.
When first proposed in 1980, the idea that an asteroid or comet impact had killed off the dinosaurs proved hugely controversial. Later, the discovery of the Chicxulub Crater in the Gulf of Mexico was hailed as "the smoking gun" that confirmed the theory.
The discovery of a second impact crater suggests that the dinosaurs were driven to extinction by a "double whammy" rather than a single strike.
The Boltysh Crater in Ukraine was first reported in 2002. However, until now it was uncertain exactly how the timing of this event related to the Chicxulub impact.
In the current study, scientists examined the "pollen and spores" of fossil plants in the layers of mud that infilled the crater. They found that immediately after the impact, ferns quickly colonised the devastated landscape.
Ferns have an amazing ability to bounce back after catastrophe. Layers full of fern spores - dubbed "fern spikes" - are considered to be a good "markers" of past impact events.
However, there was an unexpected discovery in store for the scientists.
They located a second "fern spike" in a layer one metre above the first, suggesting another later impact event.
Professor Simon Kelley of the Open University, UK, who was co-author on the study, said: "We interpret this second layer as the aftermath of the Chicxulub impact."
Previously, scientists had identified a huge impact crater in the Gulf of Mexico as the event that spelled doom for the dinosaurs.
Now evidence for a second impact in Ukraine has been uncovered.
This raises the possibility that the Earth may have been bombarded by a whole shower of space rocks.
The new findings are published in the journal Geology by a team lead by Professor David Jolley of Aberdeen University, UK.
When first proposed in 1980, the idea that an asteroid or comet impact had killed off the dinosaurs proved hugely controversial. Later, the discovery of the Chicxulub Crater in the Gulf of Mexico was hailed as "the smoking gun" that confirmed the theory.
The discovery of a second impact crater suggests that the dinosaurs were driven to extinction by a "double whammy" rather than a single strike.
The Boltysh Crater in Ukraine was first reported in 2002. However, until now it was uncertain exactly how the timing of this event related to the Chicxulub impact.
In the current study, scientists examined the "pollen and spores" of fossil plants in the layers of mud that infilled the crater. They found that immediately after the impact, ferns quickly colonised the devastated landscape.
Ferns have an amazing ability to bounce back after catastrophe. Layers full of fern spores - dubbed "fern spikes" - are considered to be a good "markers" of past impact events.
However, there was an unexpected discovery in store for the scientists.
They located a second "fern spike" in a layer one metre above the first, suggesting another later impact event.
Professor Simon Kelley of the Open University, UK, who was co-author on the study, said: "We interpret this second layer as the aftermath of the Chicxulub impact."
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