A fossilized capybara tooth found in the Atacama Desert in northern Chile has sparked new questions about the region's ancient climate. The tooth, dated to about 9 million years ago, was discovered in sediment layers that were once part of a shallow marine environment. This location, known as El Morro, is part of the fossil-rich Bahía Inglesa Formation. The study, published in the journal Scientific Reports, marks the first known record of a capybara in coastal Chile, a region where these animals no longer exist. Capybaras are large, semiaquatic rodents that rely on consistent access to water and riparian (riverbank) habitats. They are typically found in wet, tropical environments, making their presence in what is now one of the world’s driest places puzzling. Priscilla Martinez, the lead author of the study and a doctoral student at the University of Arizona, called the discovery "freakish," given the extreme aridity of the Atacama today. The research team suggests that capybaras may have migrated across the Andes through low-elevation wetlands, following a counterclockwise path from what is now Venezuela through Colombia, Ecuador, and Peru into northern Chile. This movement would have required a much wetter climate and the presence of surface water, which is supported by the discovery of fossils from freshwater fish and gavials (a type of freshwater crocodile) in the same sediment layers. Additionally, the team found phytoliths—tiny, silica-based structures formed in plant tissues—that indicate the presence of palms and other flowering plants, which are not common in today’s Atacama Desert. This finding challenges the long-held belief that the Atacama has been a dry region for millions of years. Mark Clementz, a paleobiology expert and co-author of the study, noted that the discovery suggests a wetter past and a possible transcontinental migration route for capybaras. The implications of this research extend beyond the Atacama, as it helps scientists understand how desert climates have changed over time and how they might respond to future climate shifts.