UNM Assistant Professor of Anthropology Sherry Nelson spends as much time peering at teeth as a dentist, but her time is in the laboratory looking at teeth of animals who roamed the earth in the Miocene era between 6.3 and 12 million years ago. Nelson’s fascination with this era is because that’s when the earth’s climate and ecology were changing into something close to the world we see now.
Photo: Sherry Nelson
Nelson uses the information from the teeth of primates - artiodactyls, perissodactyls and proboscideans - to understand what they ate. It’s an indirect way to determine what kind of vegetation grew in northern Pakistan where the fossils were collected. The Potwar Plateau, south of Islamabad is a special place where researchers can find a variety of fossils from the past 20 million years. They are easily accessible as erosion exposes them.
Nelson is part of a group of researchers investigating the way a changing climate impacted vegetation and the animals who fed on it. As the landscape changed from forest and woodlands to savannah, they found three things. Most forest browsers maintained dietary habits and disappeared. Some species adapted their diet to include different plants and persisted for another million years. And a few species kept altering their diet as climate changed and survived the transitions.
Their findings are detailed in a recent paper published by the National Academy of Sciences. It can be found at: Miocene Mammalian Record.
Nelson examines carbon and oxygen isotopes in the teeth. These isotopes vary in plants according to how much water and light stress they are under, as well as how plants photosynthesize. An animal incorporates these isotopes from its diet into tooth enamel as teeth form. Isotopes in teeth, then, reflect the foods and habitats an animal exploited, ranging from forest floor and canopy to grasslands.
Nelson combines isotopic information with findings from examining microscopic wear on tooth surfaces. She said, “I look at tiny little bits and scratches on the teeth, because they reflect the physical properties of food chewed. If you change your diet, the wear features will show those changes in a matter of days.” Her research interests are reconstructing the ecology of these past animals. She said she wants to know what they ate. What kind of habitat did they have? What was the climate like?
The research team includes Catherine Badgley, University of Michigan; John C. Barry and Michelle E. Morgan and David Pilbeam from Harvard University; Anna K. Behrensmeyer from the National Museum of Natural History at the Smithsonian Institution; and Thure E. Cerling from the University of Utah
Nelson says she is still very interested in working in Pakistan, but members of the research group haven’t been able to conduct field work there recently because of political instability and potential terrorist activity.
Media Contact: Karen Wentworth, (505) 277-5627; e-mail: kwent2@unm.edu
Posted by scarr at November 26, 2008 04:35 PM