It was probably during these times of ecological perturbation that the real winnowing took place. The marine algae recovered quickly, but a closer look at the post-catastrophe oceans indicates that animal life was disrupted so severely that the world slipped back into an archaic state more similar to the time when there were only microbes. And the same pattern is seen after an even greater catastrophe that occurred about 250 million years ago. There may be lessons for us. Nature is resilient, but not infinitely so.
Complex life occupies a thin veneer and is enmeshed in a dense set of ecological networks.
Pull these apart, be it by impacting meteorite or human meddling, and ultimately we may find we have inherited a world that has regressed to its microbial infancy. In one sense we owe our origins to that rogue meteorite that extirpated the dinosaurs, and gave the mammals their chance. Yet the reality of evolution permeates our entire bodies. We could neither see nor breathe were it not for microbial biochemistries that evolved billions of years ago. So too my arm once slithered across a Devonian mud-bank and hundreds of millions of years later swung from a Miocene tree.