Ferns first appear in the fossil record 360 million years ago in the late Devonian period[5] but many of the current families and species did not appear until roughly 145 million years ago in the early Cretaceous, after flowering plants came to dominate many environments. The fern Osmunda claytoniana is a paramount example of evolutionary stasis. Paleontological evidence indicates it has remained unchanged, even at the level of fossilized nuclei and chromosomes, for at least 180 million years.[6]
Ferns are not of major economic importance, but some are grown or gathered for food, as ornamental plants, for remediating contaminated soils, and have been the subject of research for their ability to remove some chemical pollutants from the air. Some are significant weeds. They also play a role in mythology, medicine, and art.
