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Mass extinctions are thought to produce ‘disaster faunas’, communities dominated by a small number of widespread species. Here, Button et al. develop a phylogenetic network approach to test this hypothesis and find that mass extinctions did increase faunal cosmopolitanism across Pangaea during the late Palaeozoic and early Mesozoic.
The authors provide evidence for the existence of life on Earth in the earliest known sedimentary rocks and suggest that the presence of organic carbon, and low stable-isotope values of graphite from sedimentary rocks in Labrador pushes back the existence of organic life to beyond 3.95 billion years.
Polypterid fish were considered to be archaic outliers of the bony-fish grouping. Fossil analysis now places them at the heart of early ray-finned fishes, a radical change that transforms the timing of their evolution. See Letter p.265