A paleontological team that includes scientists from the American Museum of Natural History; University of California, Santa Barbara; and Case Western Reserve University has described two ancient species of South American rodents, including the oldest chinchilla, a discovery that substantiates what might be the earliest grasslands in the world. The two new species lived near a chain of volcanoes about 32.5 million years ago in what are now the steep slopes of a river valley in the Chilean Andes. Studies of the teeth of the ancient chinchilla support evidence from other species in the concurrent fauna indicating that the animals inhabited an open and dry environment 15 million years before grasslands emerged elsewhere in the world. The research is published this week in American Museum Novitates, a peer-reviewed scientific journal of the American Museum of Natural History.
"The new chinchilla fossil provides important new evidence that early rodents joined other South American mammals in evolving ways to cope with an abrasive diet long before horses, sheep and other mammal groups on other continents 'invented' similar adaptations for making their teeth wear out more slowly while eating tough grasses," said John Flynn, Frick Curator of Fossil Mammals and dean of the Richard Gilder Graduate School at the American Museum of Natural History, who is a co-author of the paper.
Flynn and colleagues have explored the fossil history preserved in the Chilean Andes for the past 25 years. In the Tinguiririca River valley, an area near the border of Chile and Argentina once thought to be inhospitable to fossils because of the dominance of volcanic rocks, the researchers have uncovered hundreds of specimens, including the two newly named species of early South American rodents.
The new specimensAndemys termasi, for which the genus name means "mouse of the Andes" and the species name refers to the nearby town of Termas del Flaco, and
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American Museum of Natural History