I am interested in the extinct mammals of Peru for many of the same reasons I am interested in the extinct mammals of Bolivia. Therefore, I jumped at the opportunity to collaborate with a French and Peruvian research team led by Pierre-Olivier Antoine on a project searching for mammal fossils in the eastern part of Peru near the town of Contamana. Through this collaboration, I not only studied specimens they had collected in previous years, I was able to be part of the field team in 2011. It was a fascinating experience for me, as fieldwork near Contamana is quite unlike what I am used to in Bolivia and Chile. For example, we were looking for fossils in hot, humid lowland rainforest rather than in high, dry mountains and plateaus. Additionally, we were mostly finding tiny fossils in very limited areas through a process known as screen-washing. This essentially involves using sieves to wash large amounts of mud and sand in the river , thereby separating out tiny fossil teeth and bones (as well as similarly sized pieces of rock). The fossils and rocks are subsequently sorted using a low-powered microscope. Through this process, it is possible to find teeth of very small mammals that are often missed using more traditional fossil-hunting methods. Most of the fossils from these sites are still under study, but some the most important ones were described in a 2012 paper in the Proceedings of the Royal Society of London. In this paper, we named three new species of rodents and identify several others that are currently the oldest rodents on the continent. They come from the Eocene Epoch and are about 41 million years old. In a more recent paper, we reviewed the many types of fossil plants and animals we have found throughout the entire sequence of rocks in the area, which spans some 60 million years.
For more information see:
- Antoine, P-O., L. Marivaux, D.A. Croft, G. Billet, M. Ganerød, C. Jaramillo, T. Martin, M.J. Orliac, J. Tejada, A.J. Altamirano, F. Duranthon, G. Fanjat, S. Rousse & R. Salas Gismondi. 2012. Middle Eocene rodents from Peruvian Amazonia reveal the pattern and timing of caviomorph origins and biogeography. Proceedings of the Royal Society B: Biological Sciences 279:1319-1326.
- Antoine, P-O., M.A. Abello, S. Adnet, A.J. Altamira, P. Baby, G. Billet, M. Boivin, Y. Calderón, A. Candela, J. Chabin, F. Corfu, D.A. Croft, M. Ganerød, C. Jaramillo, S. Klaus, L. Marivaux, R. Navarrete, M.J. Orliac, F. Parra, M.E. Pérez, F. Pujos, J.-C. Rage, A. Ravel, C. Robinet, M. Roddaz, J.V. Tejada-Lara, J. Vélez-Juarbe, F. Wesselingh & R. Salas Gismondi. 2016. A 60-million-year Cenozoic history of western Amazonian ecosystems in Contamana, eastern Peru. Gondwana Research 31:30-59.