The Empty Barrel Theory
Before it was known that Ediacaran organisms survived through the Neo-proterozoic/Cambrian
boundary, some theorized that a mass extinction put an end to the Ediacarans.
After an extinction, survivors diversify and fill ecological niches left
emptied by the extinction.
The "empy barrel theory" had it that the Cambrian explosion of
diversity was a response to extinction of the Ediacarans.
Image: Detail of painting by Mike Levielle, photographed by Sonia Boucher.