Fossil Fern | Crenulopteris acadica | Illinois

Crenulopteris acadica Pennsylvanian Carbondale Formation Coal City, Illinois Specimen approx. size: 3.125" x 0.75" Matrix approx. size: 3.125" x 1.5" *Note: the lighter half is much thinner than the darker half. Crenulopteris acadica is an extinct seed fern (Pteridosperm) known from the Pennsylvanian (Carboniferous) period, approximately 310–315 million years old. Morphology Fronds are pinnate to bipinnate, with well-defined, evenly spaced pinnae. Pinnules are typically rounded to ovate, attached directly to the rachis without a stalk (sessile). Margins commonly show the crenulated or scalloped edges that give the genus its name. Venation is open and regularly branched, with a strong midvein and secondary veins arching toward the pinnule margins.