Mark T. Clementz, Department of Geology & Geophysics, University of Wyoming
Cetaceans (e.g., whales, dolphins, porpoises) and sirenians (e.g., sea cows: manatees, dugongs) are major consumers in nearshore and offshore foodwebs and play a strong part in regulating the structure and composition of these communities today. Their earliest influence on aquatic ecosystems occurred at 50 Ma, when the first whales and sea cows appeared in the fossil record. Both geochemical and morphological evidence suggest that these groups already had a strong affinity for life in the water. New discoveries of members of each order in India and Pakistan at or shortly after this event have led to a significant accumulation of fossil material documenting most of the critical steps within the transition from terrestrial to marine ecosystems by whales and sea cows. This wealth of collected material makes it now possible to examine the evolution of these groups in a more rigorous, quantitative manner. This, in turn, can provide new insights into the relationship between ecological change and morphological evolution for these groups. The primary goal of this project is to compare the evolutionary ecology of these two groups of marine mammals (Orders Cetacea and Sirenia) in the context of environmental conditions and Cenozoic climate change. With the appearance of whales and sea cows in the Early Eocene, the evolution and diversification of both groups occurred across major episodes of significant climate change as the Earth moved from the greenhouse conditions of the early Paleogene and into the icehouse conditions of the Neogene and today. In order to effectively evaluate the impact that this climate change may have had on the evolution of each, I plan to examine specimens of whales and sea cows as components of marine food webs. This requires that I not just understand the diet or trophic position of individuals or species, but of entire, coeval marine communities. Key localities representing well preserved marine vertebrate fossil accumulations (i.e., ?bone beds?) have been identified from Eocene, Oligocene and Miocene deposits in the USA (California, Oregon, South Carolina), Egypt and New Zealand for inclusion in this study. I will primarily rely on geochemical analysis of fossil tooth enamel as a proxy for ecological information. This approach involves the analysis of the stable isotopes of calcium, carbon, oxygen, and strontium to define the trophic position, diet, and salinity tolerances, respectively, of each individual examined under this project. Thus, my research component will focus on reconstructing marine food webs from these time periods as well as defining the role of whales and sea cows within them. At the same time, my teaching component will also emphasize an integrative, big-picture approach to educate K-12 and college students on the concepts of evolution, ecology and climate change. This will be done through a combined effort of research in the field and lab and classroom activities, including theater education, to provide students with multiple methods of mental stimulation and assessment. These efforts will be achieved by incorporating these teaching activities and lessons into the current UWyo paleo research program, which will be possible through the assistance of post-doctoral fellows, graduate students, undergraduates, and high school interns funded through this proposal and other sources available at UWyo. The combined research and teaching efforts are intended to provide an opportunity for students to gain a greater appreciation for scientific thinking as well as a better understanding of the processes shaping the natural world around them.
