Cameron University’s Dr. Mike Dunn, Associate Professor in the Department of Biological Sciences, has described a new fossil plant from the 325 million-year-old Pride Mountain Formation of northern Alabama. When members of the Alabama Paleontological Society discovered fossil plant remains while hunting for sharks teeth and other marine fossils, they contacted the Smithsonian Institution, who directed them to Dunn. Dunn was recommended to lead the investigation due to his experience with plant fossils of this geological time period formally known as the Mississippian.
After a collecting trip to Alabama, Dunn returned to Cameron with hundreds of specimens. After Dunn and his team analyzed the specimens, the analysis revealed an extremely rare plant fossil assemblage.
“Because plants usually fall apart as they die, fossil plants are most commonly reconstructed by identifying individual organs such as stems, leaves, roots, and reproductive structures and then putting the plant back together like a puzzle,” Dunn explains. “That process can take many years at best. However, the Pride Mountain fossil flora turned out to be a site of exceptional preservation.”
According to Dunn, the plants discovered at the site grew as a monoculture of only one species that was preserved in a sudden but gentle muddy flood so that the plants were entombed with organs still in attachment; that is, roots to stems as well as leaves and reproductive structures to stems. In addition, the mode of burial preserved the plants as compressions that reveal external morphology as well as permineralizations (petrified fossils) that reveal internal anatomy down to the cellular level.
“This rare variation of modes and tempos of preservation allowed for the extremely rare reconstruction of an extinct plant from a single site in a single analysis,” Dunn says.
After the data were analyzed and the plant was scientifically reconstructed, Dunn contracted Cameron art major Nathanial Ruff of Lawton to artistically recreate the plant. Using the fossils and a walk across campus to observe modern analogs of the extinct plant, Ruff was able to bring this plant to life.
Dunn named the plant Winslowia tuscumbiana after the recently deceased Dr. Marcia Winslow, who described the dispersed female spores that have now been connected to the whole plant, and the Tuscumbia Mine near Tuscumbia, Ala., where the fossils were recovered. The plant is interpreted as a much-branched plant, approximately one meter tall with a bulb-like rooting structure. Small awl-shaped leaves overlapped as they covered the stem in the upper regions but fell off, leaving leaf scars on the lower portions of the stem. Reproductive structures were attached to modified leaves that were four to five times longer than the vegetative leaves.
The data were published in the International Journal of Plant Sciences in January 2012, where the plant is described as: Dunn, et al., 2012. Winslowia tuscumbiana gen. et. sp. nov. (Chaleronaceae): a cormose, heterosporous, ligulate lycopsid reconstructed from the inside out from the Pride Mountain Formation (late Mississippian/Serpukhovian) of northern Alabama.
May 1, 2012