Life returned very quickly to the Chicxulub crater after the asteroid hit Earth with an impact equivalent to 10 billion Hiroshima bombs. Microfossils found in the core sample show that life at the crater reappeared after about 30,000 years, roughly when it reappeared in other locations, according to , Christopher Lowery, a researcher at the University of Texas-Austin. “You see that resurgence across the globe”, he added.
Around 65 million years ago a massive asteroid crashed into the Gulf of Mexico causing an impact so huge that the blast and subsequent knock-on effects wiped out around 75 per cent of all life on Earth, including most of the dinosaurs. Scientists studying the crater have shown how large asteroid impacts deform rocks in a way that may produce habitats for early life.
“The asteroid itself was so large that, even at the moment of impact, the top of it might have still towered more than a mile above the cruising altitude of a 747,” writes Peter Brannen in Ends of the World. “In its nearly instantaneous descent, it compressed the air below it so violently that it briefly became several times hotter than the surface of the sun,” hitting Earth with enough force enough to lift a mountain back into space at escape velocity.
In March 2019, The Galaxy posted “The Day the Earth Rained Glass” –Prelude to Extinction that described horror of the impact. The beginning of the end started with violent shaking that raised giant waves in the waters of an inland sea in what is now North Dakota. Then, tiny glass beads began to fall like birdshot from the heavens. The rain of glass was so heavy it may have set fire to much of the vegetation on land. In the water, fish struggled to breathe as the beads clogged their gills, says paleontologist Robert DePalma about the killing field laid down soon after the asteroid impact that eventually led to the extinction of all ground-dwelling dinosaurs at the end of the Cretaceous Period, the so-called K-T boundary, that exterminated 75 percent of life.
“This is the first mass death assemblage of large organisms anyone has found associated with the K-T boundary,” said DePalma, curator of paleontology at the Palm Beach Museum of Natural History. “At no other K-T boundary section on Earth can you find such a collection consisting of a large number of species representing different ages of organisms and different stages of life, all of which died at the same time, on the same day.”
A cosmic impact powerful enough to wipe out all life on Earth’s surface would loft large amounts of rock into orbit around the sun. And most of these bits and pieces would end up falling back onto our bruised and battered planet, potentially bringing life back with them, said Steinn Sigurðsson, a professor in the Department of Astronomy and Astrophysics at Penn State University “This is peculiarly reassuring,” Sigurðsson said last month at the Breakthrough Discuss conference at the University of California, Berkeley.
“If you have a sterilizing impact — if you have a beyond dinosaur killer, something that’s going to flash fry the entire planet — there is a significant probability that some biota is ejected and returns to the planet, hopefully gently, fast enough to reseed the planet,” he added. The existence of such “space refuges” is supported by computer simulations Sigurðsson and his colleagues that tracked the trajectories of rock blasted off Earth and the other rocky planets into orbit around the sun.
Image credit top of page: With thanks to Robert DePalma. In text image, The Day the Dinosaurs Died, with thanks to BBC Bancroft