Stephen Jay Gould would have loved this:
A cataclysmic mass extinction that devastated life on Earth millions of years ago is the unlikely reason such a rich variety of life is found in the oceans today, scientists have discovered.
Around 250m years ago at the end of the Permian era the Earth experienced its most dramatic loss of life, when an estimated 95% of marine species and 70% of land animals were wiped out. Scientists are uncertain what caused the extinction, but many suspect rapid environmental upheaval caused by vast volcanic eruptions were at least in part to blame.
Scientists at the Field Museum of Natural History, in Chicago, used a new database of fossil records to study how lifeforms in the oceans changed over 545m years. Instead of finding a gradual rise in different species, they spotted a sudden explosion in marine life shortly after what paleontologists call "the great dying".
I've never understood the objections to apparent bursts of speciation in the fossil record being down to actual bursts of speciation, rather than imperfections in the fossil record. There is no reason to believe that speciation must always be a steady process. There is nothing anti-Darwinian about this: if a large number of ecological niches suddenly become available (following a mass extinction, say), previous constraints are suddenly removed, and evolution is almost bound to fill the niches as quickly as possible.