Paleontologists have long looked for the cause of the massive extinctions at the end of the predinosaur Permian period. A little more than 250 million years ago, these die-offs swept the Earth clean of most life, including almost 95 percent of species in the oceans (SN: 2/1/97, p. 74). Favorite candidate causes include severe changes in ocean chemistry, huge volcanic eruptions in Siberia, and the impact of a comet or asteroid.
Whatever the cause, a report in the July Geology indicates that the end of the Permian could have unfolded in less than 8,000 years. This strongly suggests a "catastrophic" cause for the large-scale die-off, says Michael R. Rampino, associate professor of biology at New York University.