Research Training Program

Smithsonian Institution
National Museum of Natural History

PROJECT SUMMARY
1996

Philip M. Gottshall
Moravian College
Bethlehem, Pennsylvania
Douglas H. Erwin, Ph.D.
Research Scientist
Department of Paleobiology
"The Second Summer Opportunity (SSO) was a spectacular program for developing the research from my previous year. The newest results allow for a much better understanding of the relationships of my snails than would have been possible from last summer's work. "

The genus Amphiscapha (Gastropoda: Euemphalidae):
A phylogenetic evaluation incorporating stratigraphy

ABSTRACT
Amphiscapha is a small discoidal gastropod found in the middle Pennsylvanian through the Early Permian (310-271 million years ago) stretching from western Texas through Oklahoma, Kansas, Nebraska, and Iowa, to southwestern Pennsylvania. A total of 12 species have been previously described. This contribution combines two summers of research in order to understand the precise evolutionary relationships among the species of this genus. The most common method for hypothesizing evolutionary trees uses the theory of parsimony, which assumes that evolution occurs in the most efficient manner possible. While this criteria is beneficial for setting a rigid criteria for theoretical systematists to follow, the true occurrence of parsimony in nature is highly assumptive and does not accord well with actual fossil occurrences. Using the stratigraphic record, a more realistic model was created for the evolution of this genus. While this research is important for establishing these relationships, it is more important in illustrating that paleontologists have a better arsenal of tools available for understanding the evolutionary process than most biologists have given them credit.

Letter of Gratitude