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Over the past five years Jessica Blois (above), now a postdoctoral scholar at University of Wisconsin-Madison, donned hard-hat, headlamp, and coveralls and excavated new sites near the cave's entrance as part of her Ph.D. research at Stanford University. The work was in collaboration with her advisor, Elizabeth Hadly, a former UCMP student and now a UCMP Research Associate and Professor of Biology at Stanford. Jenny McGuire, recent UCMP Ph.D. student and now a postdoctoral fellow at the National Evolutionary Synthesis Center in Durham, North Carolina, radiocarbon-dated the bones at the Center for Accelerator Mass Spectrometry at Lawrence Livermore Labs. Tony Barnosky, UCMP paleontologist, and many students from UCMP and Stanford helped with the excavations.
The Samwell Cave fossils were used to reveal how mammals responded to global warming in the past, and what we might expect as we move through our current global warming episode. The big surprise is that as climate warmed at the end of the last Ice Age some 11,000 years ago, biodiversity of small mammal species decreased, and of the survivors, a "weedy" species (deer mice) became most abundant. The research was funded by the Sedimentary Geology and Paleobiology Program of the National Science Foundation (grants EAR-0545648 and EAR-0719429 to E.A. Hadly and EAR-0720387 to A.D. Barnosky).
Work on the cave faunas continues. Allison Stegner, UCMP graduate student, began a study of the blue grouse from Samwell and other Pleistocene caves while an undergraduate at Stanford. She wants to compare them with living populations in the area to see how climate change has affected their distribution and body size. This is one of the first studies of how birds respond to climate change and has significant implications for predicting future changes in bird populations as our environment continues to change.
In the collections
Note: Collection of fossil material is illegal unless done under a permit from the National Park Service. If you think you have found a fossil on National Park lands, please contact a park representative.
Blois, J., J. McGuire, and E. Hadly. 2010. Small mammal diversity loss in response to late-Pleistocene climatic change. Nature 465(7299):771-774. DOI: 10.1038/nature09077
Feranec, R.S., E.A. Hadly, J.L. Blois, A.D. Barnosky, and A. Paytan. 2007. Radiocarbon dates from the Pleistocene fossil deposits of Samwell Cave, Shasta County, California, USA. Radiocarbon 49(1):117-121.
Furlong, E.L. 1906. The exploration of Samwell Cave. American Journal of Science 22:235-247.
Graham, R. 1959. Additions to the Pleistocene fauna of Samwell Cave, California. I. Canis lupus and Canis latrans. Cave Studies 10:54–67.Hutchison, J.H. 1967. A Pleistocene vampire bat (Desmodus stocki) from Potter Creek Cave, Shasta County, California. PaleoBios 3:1-6.
McCormick, M. 1979. Species analysis of the Triassic fauna of the Hosselkus limestone, Shasta County, California. Ph.D. thesis. University of California, Berkeley.
Merriam, J.C. 1905. The Thalattosauria, a group of marine reptiles from the Triassic of California. Memoirs of the California Academy of Sciences 5(1):1-52.
Merriam, J.C. 1906. Recent cave exploration in California. American Anthropologist 8(2):221-228.
Merriam, J.C. 1908. Triassic Icthyosauria, with special reference to the American forms. University of California Memoirs vol. 1 (1).
Sinclair, W.J. 1904. The exploration of the Potter Creek Cave. University of California Publications, American Archaeology and Ethnology 2(1):1-27.
Sinclair, W.J., and E. L. Furlong. 1904. Euceratherium, a new ungluate from the Quaternary caves of California. University of California Department of Geology Bulletin 3(20):411-418.
Treganza, A.E. 1964. An ethno-archaeological examination of Samwell Cave. Cave Studies 12:1–29.
Jessica Blois and drawers photos courtesy of Tony Barnosky; Gymnogyps leg bone photo by Pat Holroyd; all others from UCMP Archives.
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