A new study from NAI astrobiologists looks at two of the greatest mass extinctions in Earth’s history, concluding that the ecosystem collapse is attributed to a loss in the variety of species sharing the same space. It took up to 10 million years after the mass extinctions for the ecosystem to stabilize. The study correlates ammonoid diversity and disparity and ecosystem stability as represented by stable carbon isotopic records spanning the end-Permian through end-Triassic mass extinctions. Their paper appears in Geology online.