Wikimedia CommonsDrawing of a plesiosaur, a marine lizard that went extinct 66 million years agoWikimedia Commons
It was a monumental tragedy. The asteroid that struck off Mexico’s Yucatan peninsula 66 million years ago – estimated to measure ten kilometers in diameter – not only killed the dinosaurs but may also have triggered an algal bloom that contributed to a massive extinction of marine animals (Journal of Geophysical Research, December 2015). Researchers from Purdue University concluded that the asteroid’s impact opened a crater 180 km across and 20 km deep, releasing a vast quantity of tiny fireballs of rock that burned plants and animals and released nitrogen oxide. Computer simulations have indicated that these substances may have formed clouds and fallen as acid rain. This rain may in turn have increased nitrate levels in the oceans and favored an algal bloom that would have cut oxygen levels in the water and produced toxins lethal to invertebrates, fish, plants, and other marine life. This hypothesis, according to the researchers, would account for the extinction of the giant marine lizards known as plesiosaurs. It is estimated that 75% of life forms disappeared after the asteroid hit.
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