The south of the Amazon may have already been covered by dry forests, like those of the cerrado, thousands of years ago. In this project, we will seek to prove or reject this hypothesis by studying fossils accumulated in the southwest region of the biome. During the last glaciation, 115,000 to 11,000 years ago, the climate was colder and eventually drier in many parts of South America. These climates may have brought dry forests as far south as the Amazon, where fossils of large mammals such as mastodons, toxodonts and giant sloths are found. What type of environment did these animals live in? Carbon molecules preserved in bones and teeth are related to the types of plants consumed by these large mammals. Furthermore, fossil pollen grains preserved in sediments can be identified and associated with different vegetation types. By combining these approaches, we will attempt to reconstruct the landscapes in the southwestern Amazon during the last ice age, thus investigating the resilience of the forest to past climate changes.