It is time we had another fossil plant in this series. The above specimen is Neuropteris ovata Hoffmann 1826, a relatively common bit of foliage in the Upper Carboniferous of North America. This is a pteridosperm, more commonly known as a seed fern. They weren’t really ferns at all but fern-like plants with some of the first real seeds. They are usually reconstructed as trees, but were also known to be bushy or even like climbing vines.
The taxonomy (naming system) of fossil plants can be very complicated because different plant parts were given different names at different times. A single plant species, then, could have a list of names for its foliage, bark, roots, seeds, etc. The name Neuropteris usually thus refers to the leaves of this particular pteridosperm.
Neuropteris ovata is famous for its use in studies of the distribution of stomata on its leaf surfaces. Stomata, sometimes called guard cells, regulate gas exchange and moisture retention in vascular land plants. The density of stomata on N. ovata leaves in the Late Carboniferous may reflect changes in carbon dioxide levels and the expansion and contraction of tropical forests (Cleal et al., 1999).
Neuropteris ovata was named by Friedrich Hoffmann (1797-1836), a Professor of Geology at the University of Berlin. I wish I knew more about him because not only did he do considerable paleobotanical research, he was also well known for his work on volcanoes in Italy. You don’t see that combination very often!
References:
Beeler, H.E. 1983. Anatomy and frond architecture of Neuropteris ovata and N. scheuchzeri from the Upper Pennsylvanian of the Appalachian Basin. Canadian Journal of Botany 61: 2352-2368.
Cleal, C.J., James, R.M. and Zodrow, E.L. 1999. Variation in stomatal density in the Late Carboniferous gymnosperm frond Neuropteris ovata. Palaios 14: 180-185.
Hoffmann, F. 1826. Untersuchungen über die Pänzen-Reste des Kohlengebirges von Ibbenbühren und von Piesberg bei Osnabrück. Archiv für Bergbau und Hüttenwesen 13: 266-282.
Zodrow, E.L. and Cleal, C.J. 1988. The structure of the Carboniferous pteridosperm frond Neuropteris ovata Hoffman. Palaeontographica Abteilung Palaophytologie 208: 105-124.
[Originally posted on October 23, 2011.]
Mark, this reminds me of all the Lepidodendron remnants (I think) easily found in the stream valleys, just south of the terminal moraine in Holmes County (Glenmont-Killbuck area, between SR 39/60 and 520), not too far away from the COW.
For anyone interested in Pleistocene (and earlier) geology of that area, they should go visit the Killbuck Natural History Museum that was set-up by Dr. Nigel Brush, from Ashland University (http://www.killbuckmuseum.org/directions/). They have curated great fossil specimens of some of these MS-PA gymnosperms (were they all gymnosperms, or is that an out-of-date classification?), as well as bits and pieces of some of the wild megafauna from the ice ages. For a town the size of Killbuck, the museum is amazing–just beware of the hours it’s open!
Thanks, Bill! I also see lots of Lepidodendron from the area. Cool museum link. Gymnosperm is still a valid taxon. Those fossils are a mix of seedless vascular plants and early gymnosperms.