If a giant dinosaur-destroying asteroid had hit seconds later, they'd probably still be roaming Earth
If the asteroid had hit the Earth a matter of seconds earlier or later, dinosaurs could well still be doing their dinosaur thing and we would probably not exist.
That's the finding of scientists who have been digging around the massive Chicxulub Crater just off the coast of Mexico, which was created when a 15km-wide asteroid hit the Earth about 66 million years ago, an event that is believed to have led to the dinosaur die-off that wiped out giants such as Tyrannosaurus Rex.
According to a just-aired BBC documentary, The Day The Dinosaurs Died, because the asteroid hit in the shallow waters surrounding the Yucatan Peninsula - rather than plunging into deep ocean - it created a giant sulphur cloud from the underlying gypsum, which led to the global winter that killed plant and animal life, including the dinosaurs.
"This is where we get to the great irony of the story - because in the end it wasn't the size of the asteroid, the scale of blast, or even its global reach that made dinosaurs extinct - it was where the impact happened," documentary co-presenter Ben Garrod told the BBC.
"Had the asteroid struck a few moments earlier or later, rather than hitting shallow coastal waters it might have hit deep ocean," Garrod continued.
"An impact in the nearby Atlantic or Pacific oceans would have meant much less vapourised rock - including the deadly gypsum. The cloud would have been less dense and sunlight could still have reached the planet's surface, meaning what happened next might have been avoided.
"In this cold, dark world food ran out of the oceans within a week and shortly after on land. With nothing to eat anywhere on the planet, the mighty dinosaurs stood little chance of survival."
The documentary followed scientists Jo Morgan, of Imperial College London, and Sean Gulick, of the University of Texas, as they dug up and examined rock cores drilled from the Gulf of Mexico.
The samples showed the energy created by the asteroid, which created a crater about 60 miles wide and 18 miles deep, was equivalent to 10 billion Hiroshima bombs.
"Our blue planet turned grey," said Garrod, who is an evolutionary biologist. "As the lights went out, global temperatures plunged more than 10 degrees Celsius within days."
Meanwhile, documentary co-presenter Alice Roberts met up with scientists to examine fossils that revealed clues to the die-off that occurred after the asteroid's impact.
"They died suddenly and were buried quickly," Ken Lacovara, a palaeontologist at Rowan University in New Jersey, told Roberts.
"It tells us this is a moment in geological time. That's days, weeks, maybe months. But this is not thousands of years; it's not hundreds of thousands of years. This is essentially an instantaneous event."
One, said Roberts, that led to the arrival of humans.
"Just half a million years after the extinction of the dinosaurs, and landscapes around the globe had filled with mammals of all shapes and sizes," she said.
"Chances are, if it wasn't for that asteroid, we wouldn't be here to tell the story today."