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Biogeographic distribution of infected plants and the continental drift theory allow a time calibration of the phylogenetic tree of Pospiviroidae. Viroids evolved in the late Early Cretaceous shortly after the appearance of angiosperms, which constitute their only known hosts. No decline in the estimated speciation rates of Pospiviroidae is observed during the Late Cretaceous but they abruptly decreased at the Cretaceous–Paleogene boundary. However, an adaptive radiation of Pospiviroidae which occurred in the late Paleocene may reflect a recovery from the K–Pg mass extinction. The evolutionary history of viroids has been in part shaped by radiation and extinction events of angiosperms. Herein, for the first time I show the probable impact of a mass extinction event on the speciation rates of subviral pathogens, which are the simplest known lifeforms.