Isolated fossil pinnule (leaf-like segment) from a compound leaf of the seed fern *Neuropteris* sp. (pteridosperm; probably group Medullosales) from the Pennsylvanian of Mazon Creek, Illinois (PRI 49832). Specimen is on display at the [Museum of the Earth](http://www.priweb.org), Ithaca, New York. Length of specimen is approximately 13.5 cm. Model by Emily Hauf.