A fossilized capybara tooth discovered in Chile’s Atacama Desert challenges long-held assumptions about the region’s arid history, revealing a landscape once teeming with freshwater ecosystems and palm trees. The find, dating to 7–10 million years ago, suggests the desert experienced dramatic climate shifts, offering insights into how deserts respond to environmental change.
The fossil, a single tooth, is approximately two-thirds of an inch long (scale equals 10 mm or 0.4 inches) and was found at El Morro in the Bahía Inglesa Formation, a site also known for its rich whale fossils at Cerro Ballena. The study, published in Scientific Reports, was led by Priscilla Martinez, a doctoral student at the University of Arizona, who described the discovery as “just freakish” due to the unexpected location in a marine deposit. The tooth, dated to a time when the region’s climate was markedly different from today’s hyperarid conditions, challenges the notion that the Atacama has been dry for 40 million years.
A Desert Reimagined: From Wetlands to Arid Wastes
The fossil was discovered in sediments deposited by a shallow marine environment 7–10 million years ago, challenging the notion that the Atacama has been dry for 40 million years. Alongside the capybara tooth, researchers found freshwater fish, gavial fossils, and phytoliths indicating the presence of palms and other flowering plants. The study’s paleoenvironmental reconstruction depicts a late Miocene coastal wetland with Cardiatherium, an extinct relative of modern capybaras, alongside freshwater crocodiles, seals, and seabirds. Think sunny Southern California full of palm trees,
Martinez explained. You don’t really expect the Atacama Desert to have palms, and we’re not sure if they were blooming extensively there, but they were definitely there.
Researchers also identified freshwater crocodiles and seals in the same deposits, painting a picture of a coastal wetland ecosystem far removed from the desert’s current state. The presence of Cardiatherium in the Atacama Region implies the existence of substantially wetter conditions along the Pacific coast during the late Miocene than occur today. The study’s authors suggest capybaras may have migrated to coastal Chile via low-elevation routes along South America’s northern edge, rather than crossing the Andes, which would have presented a significant geographical and climatic barrier at the time.
Climate Insights: Lessons from the Past
The findings underscore the Atacama’s sensitivity to climate shifts, particularly monsoon patterns. The more we understand deserts, which are extremely sensitive to changes in climate, including shifts in monsoon intensity from year to year, the better we can predict how they fare long term,
Martinez said. The study’s analysis of phytoliths and sediment layers highlights the value of paleoenvironmental reconstruction in decoding Earth’s climatic history. Understanding past climate changes that occurred without human influence can also provide a baseline for assessing how these environments may change as a result of human-driven climate change.
The research adds to a growing body of evidence that the Atacama has experienced significant environmental changes over geological timescales. The discovery of phytoliths—microscopic silica structures formed within plant tissues—reveals clues about the vegetation growing in the region at the time. Analysis indicates the landscape supported palms and other flowering plants, including dicotyledonous plants, in stark contrast to the sparse vegetation found across the Atacama today.
Unanswered Questions: The Puzzle of Desert Transformation
Additionally, the 2026 snowfall in the Atacama, which brought rare widespread snow and subsequent wildflower blooms, illustrates the region’s ongoing climatic variability, even in modern times.
The Atacama’s unique environment also makes it a premier destination for stargazing, with its high altitude, extreme dryness, and absence of light pollution. The Milky Way has been captured over salt formations in the Valle de la Luna, highlighting the desert’s dual role as both a scientific and astronomical marvel. The 2026 snow events, documented by NASA’s MODIS satellite, further underscore the Atacama’s capacity for dramatic environmental fluctuations, even in the present day.
As climate change accelerates, understanding how regions like the Atacama have adapted to past upheavals could inform conservation strategies and climate modeling. For now, the capybara tooth stands as a rare, tangible relic of a world that once thrived where only dust now prevails.