Ancient whole-genome duplications (WGDs), also referred to as paleopolyploidizations, have been reported in most
evolutionary lineages. Their attributed role remains a major topic of discussion, ranging from an evolutionary dead end
to a road toward evolutionary success, with evidence supporting both fates. Previously, based on dating WGDs in a limited
number of plant species, we found a clustering of angiosperm paleopolyploidizations around the Cretaceous–Paleogene
(K–Pg) extinction event about 66 million years ago. Here we revisit this finding, which has proven controversial, by
combining genome sequence information for many more plant lineages and using more sophisticated analyses. We include
38 full genome sequences and three transcriptome assemblies in a Bayesian evolutionary analysis framework that incorporates
uncorrelated relaxed clock methods and fossil uncertainty. In accordance with earlier findings, we demonstrate
a strongly nonrandom pattern of genome duplications over time with many WGDs clustering around the K–Pg boundary.
We interpret these results in the context of recent studies on invasive polyploid plant species, and suggest that polyploid
establishment is promoted during times of environmental stress. We argue that considering the evolutionary potential of
polyploids in light of the environmental and ecological conditions present around the time of polyploidization could
mitigate the stark contrast in the proposed evolutionary fates of polyploids.