Retired professor tracks down rodent thought to be extinct

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A retired science education professor from Florida and a Thai wildlife biologist have recorded the first images of a living Laotian rock rat, a creature descended from a rodent family once thought to have become extinct more than 11 million years ago.

In this photo provided by Florida State University, a hunter holds a Diatomyidae in Laos in May.
Click photo for larger image.

David Redfield, a Florida State University emeritus professor, and Uthai Treesucon, an expert birder, last month tracked down the rock rat, known locally as the kha-nyou, in the limestone outcroppings near a village in Laos.

They shot video and took still pictures of it, which editors of a Florida State publication sent last week to paleontologist Mary Dawson, of the Carnegie Museum of Natural History, to make sure it truly was, in scientific terms, Laonastes aenigmamus.

"It is a Loatian rock rat in the flesh," Dr. Dawson confirmed. "Isn't that something?"

"I hate calling it a rat," Dr. Redfield said. In video footage, the animal appears to be squirrel-sized and somewhat bushy-tailed. It has long whiskers and dark fur.

"It was so docile," he said. "It really wasn't trying to escape or run away."

After spending some time with the rock rat, "we took it back to its habitat and released it," Dr. Redfield said. "It sat there and looked at us and wiggled its whiskers and wandered off into the rocks."

In an April 2005 scientific paper, mammal biologists led by Paula Jenkins, of the London's Natural History Museum, described rock rat carcasses and contended the animal was so unusual, it belonged to an entirely new rodent family, which they dubbed Laonastidae. In taxonomy, a family includes genera and species that are very similar.

Dr. Dawson and her colleagues later examined the remains, and determined that the rock rats belonged to a family called Diatomyidae, whose members were thought to have died off more than 11 million years ago.

They published their findings in a March issue of the journal Science, calling it a striking example of the Lazarus effect in mammals because of the very long gap between disappearance from the fossil record and resurrection as a living animal.

Dr. Redfield, who lives in Tallahassee and turns 75 in August, decided to look for rock rats, which are sold as food in Laotian markets, after he heard about the 2005 paper. At that time, no Western scientist had ever seen one alive.

He is a birdwatcher who, by 2004, had seen a member from every avian taxonomic family in existence, about 440 kinds of birds. He also catalogued animals he had seen on birding trips, and realized he "had been enjoying seeing representatives of 78 percent of all the mammal families on Earth," Dr. Redfield said.

So he decided to forge ahead, and the rock rat had to be added to the list. He began planning a trip with the help of Mr. Treesucon, and by the time the Dawson paper came out, "I had everything but my tickets," he said.

After visiting Thailand to see Kitti's hog-nosed bat, another unique mammal, Dr. Redfield and Mr. Treesucon stayed in a Laotian village of 17 households that took turns cooking for them each day. Local hunters helped them set traps for the nocturnal rock rat.

"We failed the first four days," Dr. Redfield said. "Nothing even took the bait, which, incidentally, was sticky rice."

But they succeeded on the fifth day, May 17, after moving to an area about a mile away. Goal accomplished, they did not attempt to catch any more rock rats. One animal was accidently killed, and its skeleton preserved for researchers.

In the video, the rock rat appears to waddle, Dr. Dawson noted. It's possible that the capture injured it in some way.

Still, "efforts have to be made to get more living ones, to keep them and maybe to do some more studies of their locomotion," she said. "We need to get somebody interested in maybe developing a captive colony in a zoo."

Villagers told Dr. Redfield that in three months of hunting, they had only found six rock rats. But in a neighboring village, the impression was that the animals were more plentiful.

It's probably better to assume the rock rat is endangered until proven otherwise, Dr. Redfield noted. Six kinds of mammals still remain on his list, but he doesn't think he'll get to see them because they are rare and could already be extinct.

"Here's this retired man who did what the biologists did not do," namely look for a live rock rat, Dr. Dawson marveled. "This guy is obviously a dynamo."

To see the video and for more information, go to

Anita Srikameswaran can be reached at or 412-263-3858.


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