A fossil of the oldest known ancestor of modern rats—an agile creature that could climb, burrow and eat just about anything—has been unearthed in China, scientists said Thursday. The newly named species Rugosodon eurasiaticus had flexible ankles for tree-climbing and sharp teeth that could gnaw both animals and plants, according to the journal Science. These adaptations helped the ancient rat-like rodents known as multituberculates become among the longest lived mammals in history, said the study led by Chong-Xi Yuan from the Chinese Academy of Geological Sciences in Beijing. Believed to originate 160 million years ago during the Jurassic Period, they...