Gillespiea randolphensis (early fern)
Three Gillespiea fragments (arrows). The image is 7 cm wide.
Photo courtesy of Walt
Cressler. A number of small, light-weight fragments of Gillespiea randolphensis have been found at floodplain pond facies at Red Hill. It's not clear whether these small plants grew near the lake or were transported there from other locations.
Gillespiea belongs to an extinct group of early "ferns" called the Stauropteridales. This group is represented by three genera (Gillespiea, Rowleya and Stauropteris) and ranges from the Late Devonian to the Late Carboniferous of Euramerica (present-day North America and Europe). They are united primarily on the basis of their stele shape (i.e., the shape of their central vascular cylinder), but they may in fact be polyphyletic.
All three genera of Stauropteridales were small and bushy terrestrial plants with non-webbed (or non-laminar) ultimate appendages (leaves). The vascular system alternates in shape and decreases in size with each branching, suggesting that growth is determinate. Branching patterns differ considerably among the species. Gillespiea randolphensis and Stauropteris burntislandica have quadriseriate branching (opposite and alternate pairs of branches). In contrast, Stauopteris biseriata had a two-dimensional, distichous pattern similar to that found in the fronds of true ferns. The third genus, Rowleya trifurcata, has trifurcating (trios) lateral branches.
Two species of the Stauropteridales, Gillespiea randolphensis and Stauropteris burntislandica, are heterosporus, while a third species, Stauropteris oldhamia, is probably homosporus. Heterospory is the possession of both microspores and megaspores. Microspores develop into sperm-producing gametophytes (sexually reproducing plants) while megaspores develop into egg-producing gametopytes; homosporus plants produce one type of spore that develops into a bisexual (with sperm and egg) gametophyte.
Another early "fern", Rhacophyton ceratangium, was also found at Red Hill. You can also learn more about Ferns.
- Books:
- Stewart, W.N and G.W. Rothwell. 1993. Paleobotany and the Evolution of Plants. Cambrige: Cambrige Univ. Press.
- Taylor, T.N and E.L. Taylor. 1993. The Biology and Evolution of Fossil Plants. New York: Prentice Hall.
- Scientific Papers:
- Cressler, W.L., 1999. "Site–analysis and floristics of the Late Devonian Red Hill locality, Pennsylvania, an Archaeopteris-dominated plant community and early tetrapod site." Unpublished Ph.D. Dissertation, Univ. Pennyslvania, Philadelphia, 156 p.
- Erwin, D.M. and G.W. Rothwell. 1989. "Gillespiea randolphensis gen. et. sp. nov. (Stauropteridales), from the Upper Devonian of West Virginia." Canadian J. Botany 67: 3063-3077.