Challenging conventional theory, new scientific research suggests the dinosaurs may have been scorched into extinction by an asteroid collision 65 million years ago that unleashed 10 billion times more power than the Hiroshima nuclear bomb. (Reuters)

One minute you're a big T-Rex, the next you're toast.

Challenging conventional theory, new scientific research suggests the dinosaurs may have been scorched into extinction by an asteroid collision 65 million years ago that unleashed 10 billion times more power than the Hiroshima nuclear bomb.

Earth's temperatures soared, the sky turned red and trees all over the planet burst into flames, said atmospheric physicist Brian Toon of the University of Colorado.

Among the few survivors would have been animals living in water or burrowed in the ground like turtles, small mammals and crocodiles.

"Essentially, if you were exposed you were broiled alive. That is probably what happened to the dinosaurs. They were big creatures that didn't have anywhere to hide," said Toon.

Scholarly debate over how the dinosaurs died is fierce and the theory put forward by Toon and others adds one more twist to the greatest forensic mystery of all time.

Despite opposition from some scientists, the idea that the dinosaurs were killed by an asteroid that slammed into Mexico's Yucatan peninsula has won general acceptance since it was first mooted in the early 1990s.

Under that argument, academics say the giant reptiles mostly froze or starved to death when a huge cloud of particles kicked up by the meteorite blocked the world's sunlight for months.

But Toon, the co-author of a study published in the Geological Society of America Bulletin in May, reckons the dinosaurs' end was even more dramatic.

Creatures living near ground zero would have been vaporized immediately while those in the Caribbean area and southern United States would have drowned in 330-feet-high tsunamis when the asteroid impacted near today's Gulf of Mexico shoreline at a speed of 33,750 mph.

Then, a column of red-hot steam and dust soared thousands of miles into space and most of it fell back toward Earth within a few hours, turning the heavens into hell.

"The entire sky would be radiating at you. It would be like standing next to a giant fire; you'd be burned very severely," Toon said, whose research is based on mathematical and computer models.

Land dinosaurs all around the world perished from the intense heat of several hundred degrees Fahrenheit, said Toon.

He agrees with other scientists that the dust cloud later cooled and blocked out the sun, but says the land dinosaurs were already history by that time.

(Agencies)