Research: Flowering Plants Evolved Seed Dispersal Early

While reproductive evolution of flowering plants (angiosperms) is traditionally linked to the end-Cretaceous biotic crisis, new research suggests angiosperm dispersal ecologies had already diversified by that time. The study is based on an analysis of flowering plant diaspores – the units comprising seeds and associated structures – from a Late Cretaceous fossil forest site in New Mexico. Flowering plants possess remarkable diversity in fruit and seed size and shape, reflecting morphology for dispersal by wind, water, and animals. This diversity is thought to have only originated during the Paleogene, despite an earlier increase in abundance and diversification of angiosperms across the Cretaceous. Here Jaemin Lee et al. suggest an earlier origin of variation in angiosperms seeds and fruits. They describe a relatively well-preserved collection of 77 diaspore morphotypes from a Late Cretaceous fossil forest in New Mexico, USA, featuring fleshy fruits and an average weight approximately the size of a blueberry. Though likely dispersed by vertebrates, their emergence may have been part of the shift to shady, humid tropical forests, rather than driven by vertebrate diversification. The results broaden "our understanding of forest ecology and plant-animal interactions during the first half of angiosperm evolutionary history," say the authors.