The Paleontology of Gran Barranca: Evolution and Environmental Change through the Middle Cenozoic of Patagonia

MADDEN, R.H., CARLINI, A.A. , VUCETICH, M.G. AND KAY, R.

La Plata

Congreso; XVI Congreso Geológico Argentino, Simposio Gran Barranca; 2005

The Paleontology of Gran Barranca: Evolution and Environmental Change through the Middle Cenozoic of Patagonia. Madden, R.H.1, Carlini, A.A. 2, Vucetich, M.G.2 and Kay, R. 1 1 Duke University Medical Center 2 Facultad de Ciencias Naturales y Museo, Paseo del bosque, 1900 La Plata Kay words: Patagonia, Gran Barranca, Sarmiento Formation The Patagonian cliff called Gran Barranca exposes the Sarmiento Formation, the most complete sequence of middle Cenozoic paleontology in South America and the only continuous continental fossil record anywhere in the Southern Hemisphere through the Middle and Late Eocene, across the Eocene-Oligocene Transition (EOT), and extending into the early Miocene. The special significance of Gran Barranca relates to the geography of Patagonia, unique in terms of its proximity to Antarctica and climatic intimacy with the Southern Ocean. Notably, the fossil record at Gran Barranca preserves a record of the evolution of high-crowned teeth among many different mammalian herbivores. The fossil mammal sequence at Gran Barranca is the standard of reference for the Middle Cenozoic throughout South America. Among the diverse paleontological and geological archives in the 285m thick Sarmiento Formation at Gran Barranca are a highly resolved phytolith stratigraphy, a rich ichnofossil record, and of course, the fossil mammals and other vertebrates. New fossil vertebrate collections are much larger than ever before available and include new and diverse small mammals collected by both dry and wet screening. The new collections use a maximally refined stratigraphic control that recognizes 49 discrete levels including some never before sampled.