The information presented here represents preliminary research as the result of ten-weeks of investigation in-residence at the National Museum of Natural History. This is not an official publication of the information.

As preliminary information, results and/or findings should not be cited as part of conclusive work. Please contact the authors first if you wish to utilize the information presented here.

Abstract

The Early Permian biota was subject to a worldwide shift from ice age to global warming conditions. Seasonal dryness occurred in many regions. The intent of this study was to generate baseline data on the vegetation of one ancient flora, to be compared with earlier and subsequent species assemblages in future studies of climate-driven ecological change.

The fossil plant species and genera of the Early Permian (Leonardian) Lueders Formation, north-central Texas, were identified and quantified. The study was performed upon seven fossil collections gathered from four localities in the Lueders Formation. This area had once been a tropical coastal floodplain.

The Early Permian ecological trend in favor of seed-producing, dryness-tolerant plants appears to have been established in the Lueders flora. Seed plants, including gymnosperms and pteridosperms, dominated the assemblages. Spore-producting plants, such as the fern Pecopteris, were uncommon.

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Introduction

During the Middle Pennsylvanian to Early Permian, the earth experienced a shift from an ice age to globally warm conditions. In addition, seasonal aridity increased in many regions, such as the tropics. This was the only period in the history of life with such a climatic shift except for the present, when human activities have led to global warming (Gastaldo et al, 1996). By studying the late Paleozoic fossil record, we may observe long-term ecological changes and begin to understand better current climate-driven ecological trends.

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Methods

For each site, fossil taxa were quantified using a system of quadrats. Each fossiliferous rock was considered a quadrat. The taxa occurring on each quadrat were recorded once. The total number of quadrats on which each taxon occurs at any given site formed its biomass estimate.

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Geological Localities

The Lueders Formation of north-central Texas was deposited during the Leonardian Age of the Early Permian, about 260 million years ago. At this time, Texas lay near the equator and was partially covered by an ocean.

The collection sites are located near Lake Kemp in Baylor County, north-central Texas.

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Results

Early Permian vegetation experienced increased aridity caused by global warming. Dryness-tolerant, seed-producing plants became dominant in plant communities over swamp-loving, spore-producing plants. The Lueders flora captured this trend: seed plant foliage was the most common element. Gymnosperm groups, mainly conifers Walchia sp. and Brachyphyllum sp., dominated the flora. Pteridosperms, seed ferns, were also common. The occurrence of remnant swamp flora, including calamite and lycopod stems and true fern Pecopteris foliage, was relatively infrequent.

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This study is restricted to drawing conclusions about a single age. However, future baseline studies may gather enough information about other geological layers to develop a chronology of changes in Early Permian floral populations.

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Citation

Gastaldo, R.A., DiMichele, W.A., Pfefferkorn, H.W., 1996. Response of Late Carboniferous and Early Permian plant communities to climate change. Annual Review of Earth Plant Science 29, 461-487.

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Acknowledgements

I would like to thank my advisor William A. DiMichele and Dan S. Chaney for patiently assisting me throughout this project. I also am pleased to have had the support of RTP director Mary Sangrey and my fellow interns. This project was funded by a grant from the National Science Foundation's Research Experience for Undergraduates Program, Award Number DBI-9820303.

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ENTOMOLOGY

Sarah Garrett
"An Inventory of Leafroller Species of Moths of the Great Smoky Mountains National Park"

Abstract / Summary

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