To add on to Chuck's post:
After so many species die out, it's also a lot easier for the surviving ones to survive as their competition and predators are all gone. So even though very small amount survive, they procreate and are able to fill the niches that the dead animals left behind. So rapid (in evolutionary time frames) speciation would happen.
After so many species die out, it's also a lot easier for the surviving ones to survive as their competition and predators are all gone. So even though very small amount survive, they procreate and are able to fill the niches that the dead animals left behind. So rapid (in evolutionary time frames) speciation would happen.