Video: Dinosaurs may still be here had asteroid hit at different time or place
In the documentary The Day the Dinosaurs Died, scientists say dinosaurs' fate may have altered had asteroid that wiped them out struck elsewhere or at another time.
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The asteroid that wiped out the dinosaurs was more than a killer rock from outer space. It was a perfect storm, according to a BBC documentary.
In fact, had the asteroid hit nearly anywhere else on Earth – or if the impact came at a different time of day – history as we know it would have been changed completely, scientists say.
Their findings are on display in the documentary The Day The Dinosaurs Died, hosted by paleopathologist Alice Roberts and evolutionary biologist Ben Garod.
To gather their evidence, researchers set up shop on a drilling rig in the Gulf of Mexico off the Yucatan Peninsula, the exact spot the 15-kilometre-wide asteroid slammed into the planet 66 million years ago.
The impact created the enormous Chicxulub crater, which measured 179 kilometres across and 32 kilometres deep. When the team dug into the rock that makes the crater its home, they found it to be packed with sulphur compounds. The team theorized that the disastrous event released 100 billion tonnes of the compounds into the air.
That massive cloud of light-reflecting dust blocked out the sun and kicked off an immediate and drastic cooling of the planet, pushing world temperatures below freezing for the next decade. Such frigid temperatures were enough to wipe out most life that survived the original impact and its resulting tsunamis, toxic fumes and molten rock that rained from the sky.
“In the end, it wasn’t the size of the asteroid, the scale of the blast, or even its global reach that made dinosaurs extinct,” says Garrod. “It was where the impact happened.”
The slightest shift in the asteroid’s trajectory would have placed that impact on a stretch of Earth that may not have been so gypsum-rich, sparing the world a life-suffocating cloud. If the trajectory remained the same, but the timing was slightly tweaked, it would have crashed into deep ocean and thrown little more than vaporized seawater into the air.
While this represented terrible luck for the giant dinosaurs and their metabolic demands, it was just the ticket for smaller creatures – including the mammals that would one day evolve into humans.
The Mammals Step Up
Contrary to widely held beliefs, mammals were doing quite well before the mass extinction that destroyed their reptilian neighbours.
A 2016 study by researchers at the University of Chicago and the University of Southampton found that early mammals had carved out a significant variety of diet and ecological co-operation, starting 10 to 20 million years before the asteroid strike.
“The early (mammals) were probably insect-eating creatures like small rodents or shrews,” wrote study co-author David Grossnickle, adding that by the time the asteroid struck “there is definitely evidence that there are some plant-eating therian mammals and some more carnivorous therian mammals.”
Some of those mammals with more specialized diets were among the casualties of the mass extinction event. However, critters that had less discerning tastes were able to survive in the incredibly harsh environment created by the cloud. As that cloud dissipated and the sun was again able to peek through, those mammals were in a prime position to thrive – a lesson for the current era of extinction around the world.
“The types of survivors that made it across the mass extinction 66 million years ago might be indicative of what will survive in the next hundred years, the next thousand,” Grossnickle said.