The asteroid that killed the nonavian dinosaurs may have also killed countless marine animals after it triggered a worldwide algal bloom, a new study finds.
The infamous 6-mile-long (10 kilometers) asteroid hit Earth about 66 million years ago, creating the Chicxulub crater, an expanse spanning 110 miles (180 km) across and 12 miles (20 km) deep, according to a blog post by the American Geophysical Union (AGU).
Upon impact, the asteroid threw a vast amount of tiny fragments into the atmosphere, where they became extremely hot from the friction of rubbing against one another. As they fell back to Earth, these fragments created a global layer of silica glass about 0.12 inches (3 millimeters) thick. That layer is now known as the Cretaceous-Paleogene boundary, according to previous studies.
The radiant heat from the superhot fragments likely killed many plants and animals (as did other deadly factors generated by the asteroid, including shock waves, fires, tsunamis and darkness, as the fragments blocked much of the sun’s light). About 75 percent of animal species went extinct, including the nonavian dinosaurs.
But it’s long puzzled scientists why many marine animals, including plesiosaurs (giant marine reptiles) and ammonites (spiral-shelled mollusks), also died, even though the water should have shielded them from the thermal radiation, the AGU said.
The researchers tackled this question in the new study. They simulated how the fragments of molten and vaporized rock would have behaved after they were blasted up and out of the atmosphere and then fell back to Earth, the AGU reported.…