The research to be conducted is the along the RÃo Santa Cruz in far southern Argentina (Santa Cruz Province). The project is critical and time sensitive because construction is beginning on two hydroelectric dams that will inundate the fossil localities to be studied. Dam site preparation and infrastructure improvement were begun along the river in 2012. Recovery of specimens from this region therefore salvages information that will otherwise soon be lost to science.
Santa Cruz Province is world-famous for its Early Miocene vertebrate fossils, which range in age from about 19 to 15 million years ago, and for its unique capacity to document the evolution and adaptations of South American (SA) anthropoid primates, also called platyrrhines or New World monkeys, that make up a significant fraction of the modern biodiversity of tropical South America (17 genera and >130 species). The fossil sites occur in the Santa Cruz Formation and document the onset of a period of climate warming called the mid-Miocene Climate Optimum (MMCO), which accounts for their occurrence 20° of latitude south of their current distributional limits. The sites contain the most complete fossil platyrrhines from their first known appearance on the continent at about 26 Ma until the Holocene. The information that has been revealed by such complete fossils has given scientists unparalleled insights into early platyrrhine biology, ecology, and phylogeny. The scientific questions to be addressed are of broad paleoanthropological and paleontological significance, and include the core specific aims of 1) the illumination of ongoing debates about the antiquity of the living zoological families of New World monkeys and an understanding of the mammalian community structure and environments in which they lived; and 2) the analysis of the responses of vertebrates to the climatic changes of the MMCO.
The conduct of the research will continue a longstanding collaboration between US and Argentinian scientists from disparate fields of primatology, stratigraphy, invertebrate and vertebrate paleontology, and geochemistry. It fosters the continued training of students and professionals including, especially, the field training of a US graduate student and several Argentinian students in paleoprimatology and vertebrate paleontology.
Paleontological research was conducted in the Santa Cruz Formation (SCF) along the Río Santa Cruz in far southern Argentina (Patagonia). The sites range in age from about 19 to 16 million years ago. The project was undertaken in response to the impending construction of hydroelectric dams that will inundate critical fossil localities and destroy paleontological resources. Recovery of specimens from this region provided significant information about the community structure of fossil mammals that would otherwise have been lost to science. The investigated fossil sites bordering the river document the onset of a period of climate warming called the mid-Miocene Climate Optimum, which accounts for the occurrence of monkeys 20° of latitude south of their current distributional limits. Also, it was important to sample the fossil localities in this area because elsewhere the SCF contains the most complete fossils specimens of this age, and is the best preserved record of South American primates from their first known appearance on the continent at about 26 Ma until the Holocene. The information that has been revealed by such complete fossils has given scientists unparalleled insights into early platyrrhine biology, ecology, and phylogeny. The core goals of the research were realized: 1) newly collected monkey specimens were recovered that further support the view that the living zoological families of New World monkeys are not represented in Patagonia. Rather, the fossils represent earlier evolutionary stages in monkey evolution prior to the evolutionary branching of the living families. 2) The localities along the river were intensively sampled for fossil content and their relative ages established (rock samples were collected for future radiometric dating). 3) The research supports the hypothesis that there are distinct biozones in the Santa Cruz Formation that document changing climatic conditions over a two-million year time interval of the MMCO. The research program continued and strengthened a longstanding collaboration between US and Argentinean scientists from the disparate fields of primatology, stratigraphy, and invertebrate and vertebrate paleontology. It increased the number and variety of fossil specimens in the museums of Argentina. It fostered the continued training of students and young professionals including, especially, the field training of a US graduate student and foreign students of paleoprimatology and vertebrate paleontology.
