The scientists behind the study believe that by nearly wiping out life in the oceans the playing field was levelled between formerly dominant marine species and others eking out an existence on the margins. In the following millennia organisms jostled for space and carved out niches. The research, published in the journal Science today, is the first to explain how modern ocean life came to be.
"It tells us that there was not an inexorable trend towards modern ecosystems," said lead scientist Peter Wagner at the FMNH. "If not for this one enormous extinction event at the end of the Permian, then marine systems today might still be like they were 250m years ago."
Marine animals to emerge after the extinction included snails, clams and crabs. Other species, such as sea lilies and lamp shells, dominant before, became less common.