Tinguiririca
Perhaps the most important of our Chilean localities is Tinguiririca, which is located in central Chile near the town of Termas del Flaco. In the transition between the warm, equitable climate of the Eocene Epoch (54.8 to 33.7 million years ago) 
and the cooler climate of the Oligocene Epoch (33.7 to 23.8 mya), numerous ‘archaic’ mammal groups went extinct while newer lineages of mammals, many with living representatives, became more diverse. Before the discovery of the Tinguiririca Fauna, this period of time was not known in the South American fossil mammal record. Therefore, many of the the mammals of Tinguiririca are new species that we have described, including the world’s oldest chinchilla. Understanding this critical time in the evolution of mammals worldwide (known as the Eocene-Oligocene transition) is essential to understanding the historic factors that influence the distribution of animals today. Our 2003 publication on the Tinguiririca Fauna was the first to describe the evolutionary effects of the Eocene-Oligocene Transition on South American mammals and habitats and reinforced the idea that non-forested, grassland-like habitats appeared earlier in South America than anywhere else in the world. A subsequent publication on the fauna included an ecological diversity analysis of Tinguiririca and a synthesis of the animal groups found elsewhere in South America at the time.
For more information see:
- Bertrand, O.C., J.J. Flynn, D.A. Croft & A.R. Wyss. 2012. Two new taxa (Caviomorpha, Rodentia) from the early Oligocene Tinguiririca Fauna, (Chile). American Museum Novitates 3750:1-36.
- Bradham, J., J.J. Flynn, D.A. Croft & A.R. Wyss. 2015. New notoungulates (Notostylopidae and basal toxodontians) from the early Oligocene Tinguiririca Fauna of the Andean Main Range, central Chile. American Museum Novitates 3841:1-24.
- Croft, D.A., M. Bond, J.J. Flynn, M. Reguero & A.R. Wyss. 2003. Large archaeohyracids (Typotheria, Notoungulata) from central Chile and Patagonia including a revision of Archaeotypotherium. Fieldiana: Geology (New Series) 49:1-38.
- Croft, D.A., J.J. Flynn & A.R. Wyss. 2008. The Tinguiririca Fauna of Chile and the early stages of “modernization” of South American mammal faunas. Arquivos do Museu Nacional 66(1):191-211.
- Flynn, J.J, A.R. Wyss, D.A. Croft & R. Charrier. 2003. The Tinguiririca Fauna, Chile: biochronology, paleoecology, biogeography, and a new earliest Oligocene South American land mammal “age”. Palaeogeography, Palaeoclimatology, Palaeoecology 195(3-4):229-259
- Wyss, A.R., J.J. Flynn & D.A. Croft. 2018. New Paleogene notohippids and leontiniids (Toxodontia; Notoungulata; Mammalia) from the early Oligocene Tinguiririca Fauna of the Andean Main Range, Central Chile. American Museum Novitates 3903:1-42.
