Collaborative Research: testing the link between climate and mammalian faunal dynamics in the early Paleocene record of the San Juan Basin, New Mexico

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Collaborative Research: Testing the link between climate and mammalianfaunal dynamics in the early Paleocene record of the San Juan Basin, New Mexico byThomas Williamson, New Mexico Museum of Natural History Foundation EAR-1325544Ross Secord, University of Nebraska, Lincoln, EAR-1325612Daniel Peppe, Baylor University, EAR-1325552ABSTRACTThe Nacimiento Formation of northwestern New Mexico contains the most complete, diverse, and longest record of early Paleocene mammal evolution known anywhere in the world, spanning from about 65.8 to 62.2 million years ago. The early Paleocene is of particular importance for understanding the evolution of modern ecosystems because it includes the first mammal-dominated ecosystems that appeared immediately following the end-Cretaceous extinction of non-avian dinosaurs. This was a time when the world was warmer than now and the climate appears to have been unstable. This study will test for a relationship between climate and mammalian faunal change in the early Paleocene, and will provide a better understanding of the role climate change played in the establishment of the earliest mammal-dominated ecosystems. This project will test if mammals responded to climate change during this critical interval of time by generating a detailed climate record, including estimates of mean annual temperature and precipitation from leaf-margin and leaf-area analyses of fossil leaves, and from the study of ancient soils. This study will also reconstruct the ancient biomes present at this time and the habitats within those biomes using stable carbon isotopes from mammal teeth, and the types of depositional environments present using sedimentology. These various proxy records will be compared to test for correlations between the mammalian faunal record and changing climate or changing biomes in the early Paleocene. Results from this study should be useful for developing more accurate models for predicting the consequences of climate change. This project will provide educational and research opportunities for high school, undergraduate, and graduate students, including Native American students from New Mexico, which are greatly underrepresented in the sciences, and "at risk" 6-8th grade students from Nebraska. The results of this research will also be incorporated into a permanent museum exhibit at the New Mexico Museum of Natural History and Science.