Crow Dog Native Ferns and Gardens: History of Ferns
Ferns are Champions of Evolutionary Stasis

Ferns first appear in the fossil record about 340 million years ago as strictly aquatic plants. Life at that time was almost exclusively aquatic. The absence of fossils in terrestrial deposits of that time suggests that dry land, and possibly the earth's atmosphere, were not suitable for life as we know it. Early on, the alternating life cycle of ferns required water for sexual fertilization, because the sperm of ferns must swim through water to reach the egg. When the ancient relatives of modern ferns ventured out to land habitats, they retained their dependency on water for fertilization. Throughout fern history, and even to the present, ferns have consistently maintained their alternating generation and water-borne fertilization life style. The Lewellyn Shale fossil pictured below from 309 MYA portrays a very close morphological similarity to modern ferns as well.

--Angiosperms become dominant
--Seed ferns become extinct in middle Jurassic Period
--The oldest extant fern species, Osmunda claytoniana, appears as fossils in ~200MYA Antarctic rocks
--Lewellyn Shale near Shamokin, PA ~309MYA
--Ferns first appeared about 340 million years ago
Fern frond fossil in the ~309 MYA Lewellyn Shale near Shamokin, Pennsylvania Artist conception of a ~300 MYA Carboniferous Swamp of the Pennsylvania Period with tree ferns, tree-size Lycopods, Seed Ferns, and other primitive plants