Dark Matter and the Dinosaurs: The Astounding Interconnectedness of the Universe

by Lisa Randall

The Permian-Triassic (P-Tr) event about 250 million years ago was the most devastating known extinction in terms of the percentage of species that disappeared from the planet. Life, including amphibians and reptiles, had blossomed both in the sea and on land for quite some time after the Devonian extinction. But that ended during the P-Tr extinction, when at least 90 percent and probably more of the species on both land and in the sea died off. The losses included surface plankton as well as bottom-dwelling species such as fixed bryozoans and corals, some shellfish, and trilobites—species that had already survived two major extinction events. On land, even insects were devastated—the only time they suffered a mass extinction. In addition, a large portion of amphibians disappeared, and reptiles—who had only emerged after the previous extinction—lost most of their member species too. The cause of the P-Tr extinction remains the subject of controversy, but massive climate change and changes in the chemistry of the atmosphere and oceans almost certainly played a role. Though the cause and mechanism are unclear, the approximately eight degree Celsius rise in temperature was likely due at least in part to massive volcanism in Siberia and the consequent enormous amount of carbon dioxide and methane emissions from the Siberian Traps. The Permian-Triassic extinction—the biggest known extinction event—is almost certainly partly the result of these volcano-induced gases that heated t...