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


Lepidodendron & Sigillaria Scale Trees

Lepidodendron Petrified Tree Root Fossil

The fossil above is a section from the root of a large sized, 100 foot (30 meter) Lycopod tree which originated over 400 million years ago. It contains deeply pitted circular patterns, but its trunk differed having deeply grooved diamond patterns. It’s a very dense, heavy fossil of petrified wood. Petrified wood materializes when plant matter is buried by sediment and protected from decay caused by oxygen and organisms. Then, groundwater rich in dissolved solids flows through the sediments, replacing the original plant material with silica, calcite, pyrite, iron or another inorganic material such as opal. This was a common occurrence in the coal swamp forests of the Carboniferous Period from about 360 to 300 million years ago during the late Paleozoic Era.

Sigillaria & Lepidodendron Tree Leave Fossils

The fossil above are leaf imprints of these giant Lycopod trees such as Sigillaria and Lepidodendron cast in coal shale. The trunks of Lycopods were topped with plumes of these long thin, grass-like leaves which were often arranged like that of a bottle brush. The trees had relatively short life-cycles growing rapidly reaching heights sometimes up to 130 feet (40 meters). Lycopod forests of plenty generated tremendous amounts of decaying peat. After millions of years, it became coal buried deeply in the ground, later, fueling the Industrial Revolution. More importantly, their decaying matter helped revolutionize Earth’s emerging forests by creating soil for trees to develop deeper root systems. This enabled new tree varieties to spread further inland without relying solely on wet swampy habitats.

Lepidodendron Scale Tree Rendition Drawing
Sigillaria Scale Trees Rendition Drawing


Botanical Names:  Sigillaria and Lepidodendron

Common Name: Scale Tree 

Kingdom: Plantae

Division: Lycopod-iophyta (oldest vascular plant group, reproduced by releasing spores)

Class: Isoetopsida (plants with hollow quill-like leaves spirally arranged on a single, unbranched vein) ie quillworts, scale trees, spike moss)

Order: Lepidondrales (primitive vascular tree-like plants related to lycopods which are loosely grouped with ferns)

Family: Lepidodencraceae (has arrangement of spores on cones born on the shoots)

Genera:  Sigillaria (possess deep lace pattern on trunk with bottle brush crown of leaves)

Genera: Lepidodendron (possess deep diamond pattern on trunk with plume of grassy leaves on crown. Roots lack diamond pattern.