At www.sciencedaily.com/releases/2010/05/100517152518.htm it is claimed a mass extinction of fish some 360 million years ago reset the button on earth’s life forms triggering modern vertabrae biodiversity. The mass extinction event, it is theorised, scrambled the species pool near the juncture when the first vertebrae were crawling out of the water on to the land. Those few species of vertebrae that survived the extinction event became the evolutionary starting point for an explosion of other vertebrae species that subsequently emerged. The study, published in Proceedings of the National Academy of Sciences says the Devonian Period, 416 to 359 million years ago, is known as the Age of Fishes. This is because it is known mainly from fish fossils in Devonian rock strata which include gigantic lungfish, the dominant species in the seas. However, in a minority were ray finned fish species, sharks and tetrapods. At the boundary between the Devonian and the Carboniferous periods there was a catastrophic disappearance of the giant lungfish – and ray finned fish replaced them as the dominant species in the sea. I should add, it is thought so. Although lungfish are still extent they are a distinct minority so the extinction event had far reaching consequences. It is unclear why groups of species abundant before the event did not recover while other groups were able to multiply and diversify in radical new ways – one of the mysteries of a number of extinction events.