Research shows how dinosaurs became extinct after asteroid hit

By the end of the disaster more than three quarters of species on Earth, including all the dinosaurs that did not evolve into birds, had been wiped out. Photo / 123RF

Dinosaurs met a hellish end as fiery brimstone rained down from the sky and broiled the Earth's surface after a massive asteroid struck the planet.

The biblical horror continued with billions of tonnes of soot from the fires blotting out the sun and plunging the Earth into icy darkness for nearly two years, new research has shown.

In addition, large-scale destruction of the protective ozone layer high in the atmosphere led to DNA-damaging levels of ultraviolet radiation.

By the end of the disaster, known as the K-Pg extinction, more than three quarters of species on Earth, including all the dinosaurs that did not evolve into birds, had been wiped out.

Scientists recreated the nightmarish aftermath of the meteor strike 66 million years ago using powerful computer simulations and evidence from the estimated 15 billion tonnes of fine soot left behind by the cataclysm.

The 10km wide space rock smashed into a shallow sea off Mexico's Yucatan peninsular, triggering earthquakes, tsunamis, volcanic eruptions and, worst of all, a burning rain of incandescent rock particles that ignited raging global fires.

Soot from the fires swept up into the atmosphere by air currents blocked out 99 per cent of the sun's light for around 18 months, making every day as dark as a moonlit night.

During this time average temperatures plummeted by 28C on land and 20C in the oceans and surviving plant life deprived of photosynthesis perished.

The 10km wide space rock smashed into a shallow sea off Mexico's Yucatan peninsular. Photo / 123RF

Lead scientist Dr Charles Bardeen, from the US National Centre for Atmospheric Research, said: "The extinction of many of the large animals on land could have been caused by the immediate aftermath of the impact, but animals that lived in the oceans or those that could burrow underground or slip underwater temporarily could have survived.

"Our study picks up the story after the initial effects - after the earthquakes and the tsunamis and the broiling. We wanted to look at the long-term consequences of the amount of soot we think was created and what those consequences might have meant for the animals that were left."

The study, published in the journal Proceedings of the National Academy of Sciences, raises the frightening prospect of what might happen to the Earth after a global nuclear war.

- AAP