Maestrichtian Land Mammals of Vega Island, Antarctic Peninsula

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OPP 9615236 Woodburne OPP 9615933 Case Abstract The Maestrichtian is considered to have been a key interval in the development of the land mammal fauna of southern Gondwana from Australia to Antarctica and South America. Up to now, no Maestrichtian fossil land mammals have been found in any of these continents. The Lopez de Bertodano Formation of Vega Island, Antarctic Peninsula, shows the best potential of yielding remains of land mammals of Maestrichtian age in any southern Gondwana location. This project is designed to grasp that opportunity as a collaborative venture between St. Mary's University, University of California, Riverside, and Argentine scientists. Current theory predicts that the presently unknown Maestrichtian- age land mammal fauna in Antarctica should consist (1) of a suite of non-therian taxa remnant from an Albian-Campanian fauna that occupied southern Gondwana from Australia to Antarctica to South America and (2) a complex of marsupials composed of relict peradectids and more derived early members of australidelphians. The australidelphians should include early members of the (currently) South American Microbiotheriidae as well as early lineages of the (currently) Australian Peramelina, Dasyuromorphia and Diprotodontia. This awards supports work to test this hypothesis in terms of the composition of the Maestrichtian land mammal fauna by conducting field research in Vega Island of the James Ross Island basin, Antarctic Peninsula. The location has been chosen on the basis of its known productivity in yielding Maestrichtian-age vertebrates (presbyornithid birds and hypsilophodont dinosaurs) in near-shore fine-grained shallow-water marine sandstones of the Lopez de Bertodano Formation that are amenable to dry or wet sieving collecting methods, methods that have proven successful in obtaining fossil mammals from similar facies in the medial Eocene La Meseta Formation of Seymour Island. This is a cooperative project with the Antarct ic Institute, Argentina, (IAA) and the Museo de La Plata, Argentina (MLP). MLP personnel are collaborating on research into the evolutionary history of Late Cretaceous to early Tertiary therian mammals in South America and Antarctica and the potential relationship of these to the early population of Australia. The collaboration with IAA personnel is focused on litho- and biostratigraphy of the marine successions. The first grant year (1997) will focus on examining existing material. Years 2 and 3 will focus on field work on Vega Island and follow up examination of any fossil discoveries. The IAA will supply all Antarctic logistic support for US as well as Argentine personnel, including travel from Argentina to Seymour Island, and logistical support in the field. Collaborative visits to participating institutions will occur as required over the life of the project.