I am inordinately fond of mass extinctions. I find them consoling.
The most recent mass extinction, the newly-famous Yucatan-comet-iridium K-T boundary event of 66 million yeas ago is one of my personal favorites. To recall: a comet six or seven miles in diameter, zooming along at 65,00 miles per hour and therefore generating a good bit of momentum, smacked into what is now the Yucatan peninsual with the force of a heck of a large number of hydrogen bombs. The impact produced a crater that was initially an astonishing 65 miles across and 18 mles deep, triggered massive earthquakes as well as tsunamis half a mile high, and briefly heated the earth's atmosphere to hundreds of degrees. Within minutes, everything as far as Illinois became wasteland. Because of the blanket of smoke and dust, sunlight could not reach the earth, so temperatures plummeted, completely disrupting the world-wide chlorophyll-based food chain. At the same time, downpours of acid rain corrosive enough to dissolve rocks killed everything they touched. A full 80% of all animal species disappeared -- along with half of all land plants.
Although it must have been quite a show, it was not as thorough a disaster as the Permian extinction (252 million years ago) which killed 95% of all living species, but it is, rather, comparable to the Ordovician extinction (444 million years ago), the Devonian (375 million years ago) and the Triassic (201 million years ago). It's no wonder that folks in the know estimate that 99.9% of all the species that have ever existed have disappeared.
The knowledge that there will inevitably be another extinction helps to put our daily woes in perspective. How can I worry about the color of the grout or my newest skin growth when our species and the cool green earth itself are doomed. Judgment day is coming, whether in the form of another wayfaring comet, or a series of explosive volanoes, or the release of nitrogen and carbon now sequestered in the permafrost, or some event entirely unpredictable. Something is going to happen as sure as shooting. Perhaps, some think, it's already happening.
So that's one benefit of a mass extinction -- it helps you sleep well at night. Why worry?
And also: if it weren't for the extinctions, we wouldn't be here at all. If the dinosaurs hadn't been killed by the comet they would most likely have continued to dominate the planet, and the descendants of velociraptors and mosasaurs and thunder-lizards sure as heck weren't going to leave a lot of breathing room for proto-primates.
Extinctions are one of the many improbable accidents that got us here. Extinctions are joyful.