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Geologic time scale showing major mass extinctions and the occurrence in time of the main groups of vascular plants on land. 1 = spore-bearing plants including lycopsids and ferns; 2 = gymnosperms; 3 = angiosperms (numerical ages from ref. 1 and Geologic Time Scale, Geological Society of America, http://www.geosociety.org/pubs/index.htm). Ma, millions of years. Red line indicates time discussed by Looy et al. (1).
