Researchers at Purdue University have identified a cloud of microscopic dust as the primary driver of the mass extinction that killed the dinosaurs 66 million years ago, according to a new study.
A rock the size of Everest struck the Yucatan Peninsula, creating the Chicxulub crater and wiping out nearly 75 percent of all species on Earth. Scientists have long sought to understand how a single collision could devastate an entire global ecosystem.
Scientist Brandon Johnson analyzed the physics of the event and found that the impact released enormous kinetic energy, vaporizing more than 1,000 cubic kilometers of rock and earth. That material rose above the atmosphere, cooled into tiny solid droplets called spherules, and then reheated as friction slowed their fall back to Earth.
The decisive factor, however, was an immense blanket of ultrafine dust that stayed suspended in the upper atmosphere. Cloud expert Alexandria Johnson collaborated on that part of the analysis. The particles measured just 2.5 micrometers, about 30 times thinner than a human hair, and acted like a lid on a boiling pot, blocking heat from escaping into space.
Thermal radiation bounced back to Earth’s surface, exposing Cretaceous animals to levels 17 times the dose that would be 100 percent lethal to a human. The heat was sufficient to spontaneously ignite grass, leaves, moss, and wood, setting off wildfires on a global scale. The sky fell into near-total darkness, with the reddish glow of fire as the only visible light.
Survival depended on burrowing underground, submerging in water, or finding thermal insulation. The fine dust remained in the skies for years or decades, and animals that escaped incineration faced serious health consequences from inhaling the toxic particles.
