Frond of Pecopteris, a true fern. Large numbers of small leaves are typical of this true fern living in the coal swamps some 300 million years ago during the Pennsylvanian Epoch, Carboniferous Period. Grew as shrubs and thick-trunk trees up to 50 ft. high. Unlike most other dominant spore-producing plants of the time, true ferns have survived to the present. Specimen courtesy of Pennsylvania State Museum, Klose Coal Fossil Collection.