New research suggests that fine silicate dust kicked up by the asteroid impact 66 million years ago was the primary driver of the mass extinction that wiped out non-avian dinosaurs. The study, published in Nature Geoscience, used computer simulations to assess the 'killing mechanisms' following the Chicxulub impact in what is now Mexico's Yucatán peninsula.
While soot from wildfires, volcanic eruptions, and sulphur have been considered culprits, the researchers argue that trillions of tonnes of dust from pulverised granite and rock played a crucial role. The simulations, based on dust particles recovered from a site in North Dakota, showed that dust could have remained in the atmosphere for up to 15 years, blocking sunlight and causing a global winter.
The dust reduced photosynthesis for nearly two years and cooled the planet by up to 15°C, according to the models. 'The silicate dust most likely drove the last mass extinction event through the disruption of photosynthetic activity,' said Cem Berk Senel of the Royal Observatory of Belgium. Co-author Philippe Claeys added that the dust was the 'most efficient blocker of photosynthesis,' rendering the atmosphere opaque to sunlight.
Steve Brusatte, a palaeontologist at the University of Edinburgh not involved in the study, described the asteroid as 'apocalyptic' but noted that the real killer was the aftermath. 'The asteroid didn't kill all the dinosaurs in one go, but it was a more stealthy murderer, which triggered a war of attrition that led three out of every four species to die,' he said.
