Relationship between extinction rates and the time interval over which the rates were calculated, for mammals. Asterisks indicate taxa for which very few species (less than 3% for gastropods and bivalves) have been assessed white arrows show where extinction percentages are probably inflated (because species perceived to be in peril are often assessed first). Yellow icons indicate the Big Five species losses: Cretaceous + Devonian, Triassic, Ordovician and Permian (from left to right). Black icons add currently ‘threatened’ species to those already ‘extinct’ or ‘extinct in the wild’ the amphibian percentage may be as high as 43% (ref. White icons indicate species ‘extinct’ and ‘extinct in the wild’ over the past 500 years. Numbers next to each icon indicate percentage of species. Extinction magnitudes of IUCN-assessed taxa 6 in comparison to the 75% mass-extinction benchmark.
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