'New' Rodent Proves to be Ancient Animal

WASHINGTON —  It was thought to have gone extinct 11 million years ago — a chipmunk-size, brush-tailed rodent with a long head and quick paws well-suited for scooting across the rock escarpments of ancient China and Pakistan.

Then last year in central Laos, Western scientists spotted an unusual animal carcass in a meat market near the Mekong River. So unusual, in fact, that it turned out to represent a new rodent family — the first new mammal family to be announced in 30 years. The researchers called it Laonastes aenigmamus —  the Laotian "rock rat." Local people call it "kha-nyou."

It turned out that kha-nyou is a textbook example of a phenomenon known as the "Lazarus effect." A creature, thought to have died out deep in the prehistoric past, suddenly reappears. Kha-nyou, researchers said yesterday, is a modern member of an ancient rodent family last seen as an 11 million-year-old fossil paleobiologists call Diatomys shantungensis.

"Laonastes didn't rise from the dead," explained Carnegie Museum of Natural History paleontologist Mary Dawson. "You're doing the research, and then you find a gap in the fossil record." What happened to Diatomys between 11 million years ago and now is unknown, but not because it went extinct. Scientists simply have not found more fossils.

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Source: Washington Post