Scientists have found a tooth of a 9-million-year-old capybara relative in Chile’s Atacama Desert, one of the world’s driest places; water-loving animal adds evidence that the region once supported wetlands and a very wet climate

The Atacama Desert is a place where water is measured in millimeters, not rivers. Today, parts of this vast Chilean desert receive almost no rain, making the discovery of an animal that relies on so much fresh water all the more surprising. Buried in an ancient site, the single tooth has now given scientists another chance to show how different the Atacama is, with wetlands, vegetation and enough water to support a giant, aquatic rodent.According to a Live Science report, researchers have identified a 9-million-year-old tooth as belonging to an extinct relative of today’s capybaras, adding to growing evidence that the Atacama was not hyperarid throughout its long geological history.

An amazing fossil in the desert

The Atacama occupies northern Chile and is considered one of the oldest and driest deserts on Earth. Its hyperarid core receives less than 2 millimeters of rain per month in some areas. The region’s extreme aridity is partly linked to its location. The Chilean Coast Range blocks moisture from the Pacific, while the Andes limit moisture from the Atlantic. However, geological research suggests that the desert began to form millions of years before the Andes reached its peak, adds a Live Science online report.The newly discovered tooth provides another reason to re-examine what the region looked like in the past, the report said.According to Live Science, the fossil belonged to a large relative of the capybara identified as Hydrochoerus and Cardiatherium, which lived during the late Miocene. Modern capybaras are the largest rodents in the world and are highly dependent on a stable environment with fresh water. They eat plants that need enough water to grow. So finding one in today’s Atacama points to a place markedly different from the desert landscape seen today.

Evidence of an ancient wetland

The tooth was found in a layer containing evidence of a shallow marine environment that existed between 7 and 10 million years ago, the report said. It wasn’t a single clue. Researchers have found remains of small plants known as phytoliths, which show that palms, grasses, ginger and other flowering plants once grew in the region. Together, these discoveries paint a picture of a land that supported water and vegetation at times better than the Atacama does today.Other fossil evidence from the region points to freshwater fish and crocodiles, which reinforces the possibility that wetlands and waterways spread from time to time throughout the desert. The capybara relative adds another piece to that ecological puzzle because its aquatic lifestyle would require access to reliable water.

How do capybaras get there?

According to Live Science, the discovery also raises the mystery of the place. The Andes presented a great barrier between the possible habitats of this animal farther east and the fossil site in northern Chile, with an elevation of about 5,500 meters. The researchers suggest that these animals may have traveled along the west coast of South America, moving between swamps, rivers and other freshwater habitats. The tooth itself also makes long distance transport an impossible explanation. Its size makes it difficult to imagine it being carried by the wind for hundreds of kilometers, while a waterway capable of transporting such things would itself point to a wet area.

A changing image of the Atacama

The fossil does not mean that the entire Atacama was once a pristine place. Rather, it reinforces the case that the region experienced periods of very wet conditions during the late Miocene. In a desert known for its extreme dryness, a small piece of debris offers a surprisingly large lesson: places that seem eternally hostile today can have remarkably different histories. The capybara’s tooth is another piece of that history, revealing a time when water-loving mammals were able to survive in an area that now seems almost entirely defined by its absence.Images Courtesy: iStock and Science Alert