Why the Dinosaurs Died

"The age of the dinosaurs ended 66 million years ago when a city-size asteroid struck a shallow sea off the coast of what is now Mexico," writes CNN. "But exactly how the mass extinction of 75% of the species on Earth unfolded in the years that followed the cataclysmic impact has remained unclear."Previous research suggested that sulfur released during the impact, which left the 112-mile-wide (180-kilometer-wide) Chicxulub crater, and soot from wildfires triggered a global winter, and temperatures plunged. However, a new study published Monday in the journal Nature Geoscience suggests that fine dust made from pulverized rock thrown up into Earth's atmosphere in the wake of the impact likely played a greater role. This dust blocked the sun to an extent that plants were unable to photosynthesize, a biological process critical for life, for almost two years afterward. "Photosynthesis shutting down for almost two years after impact caused severe challenges (for life)," said lead study author and planetary scientist Cem Berk Senel, a postdoctoral researcher at the Royal Observatory of Belgium. "It collapsed the food web, creating a chain reaction of extinctions." To reach their findings, scientists developed a new computer model to simulate the global climate after the asteroid strike. The model was based on published information on Earth's climate at that point in time, as well as new data from sediment samples taken from the Tanis fossil site in North Dakota that captured a 20-year period during the aftermath of the strike.

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