Abstract Detail

Paleobotanical Section

Axsmith, Brian [1], Stults, Debra [2].

Fagaceae from the Pliocene Citronelle Formation of Alabama.

Ongoing studies of the Pliocene (Piacenzian) Citronelle Formation in Alabama continue to provide new information from a poorly know time in the evolution of the Eastern Deciduous Forest. As is true for the extant flora of south Alabama, the Fagaceae is particularly well represented. In the original description of this flora, Berry (1916) described a leaf as Fagus lambertensis. Results of our reexamination of the original specimen are inconclusive. However, a newly discovered specimen is most likely a species of Fagus, which may be related to Asian species such as F. hayatae based on its small size and cuneate base. New collections include Castanea leaves similar to those of extant C. dentata and C. pumilla. Berry assigned several leaves to Quercus. Q. catesbaeifolia was named as a new species similar to extant Q. laevis. Examination of his specimen and new material suggests these fossils are probably conspecific with the extant taxon. Similarly, Berry’s Q. lambertensis fossil and newly collected specimens are indistinguishable from extant Q. falcata. Leaves identical to Q. virginiana are common and we propose that Berry’s Q. previrginiana specimens are also representative of the extant species. Characteristic acorn cups and cuticular features support this identification. Q. phellos is represented by a single specimen. Berry assigned a partial leaf to Q. nigra, but it is atypical. A newly collected specimen shows the more common shallowly lobed apex morphology with bristle tips verifying the presence of this species. A Quercus catkin with in situ pollen has also been recovered. Many of these fossils are significant in being the earliest record of their species, and support the concept that components of the Gulf of Mexico Coastal Plain flora have been remarkably stable for at least the last 3 million years.

Broader Impacts:
The Fagaceae is a major component of the Eastern Deciduous Forest. This research provides the first records of several important species and is, therefore, of interest in understanding the biogeographical, phylogenetic, and paleoclimatic history of this important ecosystem.

1 - University of South Alabama, Biological Sciences, Life Sciences Building 124, Mobile, AL, 36688, United States
2 - University of South Alabama, Department of Marine Sciences, Life Sciences Bldg 25, Mobile, Alabama, 36688, USA

Keywords:
Fagaceae
Fagus
Quercus
Castanea
Pliocene.

Presentation Type: Oral Paper:Papers for Sections
Session: 58
Location: 556A/Convention Center
Date: Wednesday, August 4th, 2010
Time: 1:45 PM
Number: 58002
Abstract ID:271