Document Type
Thesis
Abstract
Recent projections of anthropogenically-influenced climate change have emphasized the importance of understanding how organisms respond to long-term climate change, using data from the fossil record. Past studies have focused primarily on quantifying the ecological and biogeographic effects of climate change, with relatively little attention paid to the evolutionary response of faunas. The goal of this research is to begin to explore whether the evolutionary history of planicostate venericards was significantly impacted by Paleogene climate change along the U.S. Gulf Coastal Plain. By reconstructing venericard phylogenetic history, quantifying morphology and comparing both to broad records of climate change during the Paleocene and Eocene it is possible to begin to study the relationship between climate and evolution in the genus. Field and museum specimens were used to provide a record of morphologic and phylogenetic change in venericard bivalves during the Paleocene and Eocene (Appendix 1). Specimens were collected from eleven localities in Alabama and Mississippi and supplemented with museum specimens from the Smithsonian Museum of Natural History (DC), Virginia Museum of Natural History (VA), Mississippi Department of Environmental Quality (MS) and the Paleonotological Research Institute (NY) in order to increase species sample size and examine rare species. Digital images of venericards in lateral orientation were taken and morphology was quantified using thirteen prominent landmarks, distributed along the beak, hinge, adductor muscles, and shell outline. A venericard phylogeny was reconstructed using 40 characters compiled for 17 taxa. To explore the evolutionary response of planicostate venericards to climate change, we qualitatively compared morphological and phylogenetic patterns with paleoclimate data across this interval. Results indicate that some of the early hypotheses about venericard systemmatics and phylogentics are correct, but a few relationships are disproven using these more quantitative techniques. In addition, the quantitative methods used here give a better understanding of the extent to which lithologic, climate trends, and productivity factors influence changes in venericard size and shape (morphology) over the Paleocene and Eocene Epochs. Since venericards, particularly planicostate species, have received little attention in recent years this research raises a number of possible questions for future work.
Date Awarded
2007
Department
Geology
Advisor 1
Rowan Lockwood
Recommended Citation
Fenlon, Erin E., "Quantifying the Morphology and Reconstructing the Phylogeny of Venericard Bivalves along the Gulf Coastal Plain during the Paleocene and Eocene" (2007). Geology Senior Theses. William & Mary. Paper 172.
https://scholarworks.wm.edu/geologyseniors/172
