Pecopteris Leaf of Fern Tree

Fern leaves called Pecopteris grew abundantly in the coal swamps of the Carboniferous and Permian time periods, approximately 359-251 million years ago. These leaves dropped off a medium sized, 35 foot (10 meters) tree called, Psaronius, one of the most common Paleozoic varieties. With its expansive leaves and branches, it resembled modern day palm trees. Impressively, it produced as many as 7000 tiny spores on the underside of its leaves. These fossil samples are preserved in gray coal shale from Pennsylvania as with many Carboniferous leaf fossils.

Pecopteris Imprint Fossil Leaf from Fern Tree

If you’ll recall the differences from, Neuropteris leaflets shown on the previous page, the mid-vein stops midway up the leaflet and splits into several fine veins, whereas the mid-vein in Pecopteris extends up to the tip. Neuropteris leaflets are usually more blunt tipped and are attached by a single stem as opposed by the entire base, such as with Pecopteris. Another way to identify Pecopteris is hinted in its name, derived from the Greek word meaning, to comb. Observably, the leaflets along the stems feature an arrangement resembling that of a comb.

Pecopteris Imprint Fossil Leaflets from Fern Tree

What makes fern trees so special? The large fronds produced by Pecopteris leaves, which grew upon the ancient Psaronius fern trees, cloaked the forest floor in deep shade together with the Medullosa seed fern trees. Consequently, they protected the ancient creatures below from the strong ultra violet rays of the sun as it was closer to earth and more powerful during the Paleozoic Era. Also, the shedding and decomposing of leaves created more layers of soil for roots to extend deeper and deeper, alleviating the need for trees to grow near water pools. Trees were then able to spread further inland. Yet another benefit was that the leaves fed inland water sources cultivating more fresh water fish varieties. But this fantastic fossil is most special to me because I inherited from my late father-in-law, Joseph Mirto II. It was found in Johnstown, Pennsylvania.


Kingdom: Plantae

Division: Pteridophtya (meaning vascular plant with transport system for nutrients and fluids)

Class: Filicopsida (Ferns which reproduce with spores)

Order: Marattiales (primitive ferns)

Family: Marattiaceae

Genus: Pecopteris

Psaronius Fern Tree Rendition Drawing


Botanical Name: Psaronius Common Name: Fern Tree

Kingdom: Plantae

Division: Tracheophyta (meaning vascular plant with transport system for nutrients and fluids)

Class: Marattiopsida (distinguished by massive roots and largest fronds of all seed fern trees)

Order: Marattiales (primitive ferns)

Family: Psaronlaceae

Genus: Psaronius Species: magnificus