Chinese scientists have discovered ancient fossils in northwest China's Ningxia Hui Autonomous Region and confirmed them as a new species of rodent. Their research findings were recently published in the Journal of Vertebrate Paleontology.

The new species, named Yuomys robustus, is the largest in build and has strongest teeth among all known species of Yuomys, said Gong Hao with the Institute of Vertebrate Paleontology and Paleoanthropology under the Chinese Academy of Sciences, the first author of the study.

The scientists estimated that the new species may have weighed 485 to 880 grams, about two to three times as much as rats.

The teeth of the new species indicate that it lived in the late Eocene, about 38 million to 34 million years ago.

According to the study, from the middle Eocene to the late Eocene, the cheek teeth of Yuomys gradually enlarged while the species' tooth crown height and body mass increased.

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