Chile: Wet Dessert

Wet Desert Chile’s Atacama Desert, the world’s oldest nonpolar desert, is one of the driest places on Earth. Scientists have long believed that it has remained consistently arid for 40 million years. But now, thanks to a capybara tooth found in its sands, researchers say it was not so dry a few million years ago. “Finding a capybara tooth in a marine deposit in what today is one of the driest regions on Earth is just freakish,” said Priscilla Martinez, the study’s lead author and a doctoral student at the University of Arizona’s Department of Geosciences, in a statement. She was part of a team that discovered a fossilized tooth from an extinct capybara relative in a 3-foot-thick sediment bed at El Morro in northern Chile. The tooth, which dates to about 8.8 million years ago, belongs to the extinct genus Cardiatherium, a relative of modern capybaras. This discovery suggests that parts of the region were considerably wetter nearly 9 million years ago and were able to accommodate mammals such as the capybara even though no capybaras live in Chile today. The discovery is significant because modern capybaras, the world’s largest living rodents, are semiaquatic animals that depend on reliable water and vegetation. The tooth was not the sole evidence of a wetter environment: remains of palms and other flowering plants from roughly the same period were also identified by researchers. Together, the evidence points to a freshwater and riverside ecosystem capable of supporting large water-dependent mammals in the southern Atacama. The study, published in the journal Scientific Reports, also raises questions about how ancient animals moved across South America. Researchers say the wetlands may have been connected to other parts of the continent through routes across or around the Andes. “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,” said Martinez. “And if we can understand past climate changes that had nothing to do with humans, it gives us a baseline to work off of to understand how climate can evolve over time with humans in the mix.”