Rat-squirrel back after 11-million-year "absence"

[Lord Zentei]

Rat-squirrel back after 11-million-year absence

Scientists: Animal in Laotian jungle isn't new species, but old one

Friday, March 10, 2006; Posted: 12:24 a.m. EST (05:24 GMT)

WASHINGTON (AP) -- It has the face of a rat and the tail of a skinny squirrel -- and scientists say this creature discovered living in central Laos is pretty special: It's a species believed to have been extinct for 11 million years.

The long-whiskered rodent made international headlines last spring when biologists declared they'd discovered a new species, nicknamed the Laotian rock rat.

It turns out the little guy isn't new after all, but a rare kind of survivor: a member of a group until now known only from fossils.

Nor is it a rat. This species, called Diatomyidae, looks more like small squirrels or tree shrews, said paleontologist Mary Dawson of Pittsburgh's Carnegie Museum of Natural History.

Dawson, with colleagues in France and China, report the creature's new identity in Friday's edition of the journal Science.

The resemblance is "absolutely striking," Dawson said. As soon as her team spotted reports about the rodent's discovery, "we thought, 'My goodness, this is not a new family. We've known it from the fossil record."'

They set out to prove that through meticulous comparisons between the bones of today's specimens and fossils found in China and elsewhere in Asia.

To reappear after 11 million years is more exciting than if the rodent really had been a new species, said George Schaller, a naturalist with the Wildlife Conservation Society, which unveiled the creature's existence last year. Indeed, such reappearances are so rare that paleontologists dub them "the Lazarus effect."

Another well-known example is the coelacanth, a primitive fish that existed before the dinosaurs and was thought to have gone extinct 65 million years ago, until one was caught in 1938 off the coast of southern Africa.

"It shows you it's well worth looking around in this world, still, to see what's out there," Schaller said.

The nocturnal rodent lives in Laotian forests largely unexplored by outsiders, because of the geographic remoteness and history of political turmoil.

Schaller called the area "an absolute wonderland," because biologists who have ventured in have found unique animals, like a type of wild ox called the saola, barking deer, and never-before-seen bats. Dawson described it as a prehistoric zoo, teeming with information about past and present biodiversity.

All the attention to the ancient rodent will be "wonderful for conservation," Schaller said. "This way, Laos will be proud of that region for all these new animals, which will help conservation in that some of the forests, I hope, will be preserved."

Locals call the rodent kha-nyou. Scientists haven't yet a bagged a breathing one, only the bodies of those recently caught by hunters or for sale at meat markets, where researchers with the New York-based conservation society first spotted the creature.

Now the challenge is to trap live ones and calculate how many still exist to determine whether the species is endangered, Dawson said.

[NecronLord]

<Rat-Squirrels> You guys were supposed to seek!
<Rats> Oh... yeah...
<Squirrels> Heh heh heh.

[wolveraptor]

A mammal species surviving 11 million years? Damn.

[SVPD]

[Edi]

A mammal species surviving 11 million years? Damn.

Hey, squirrels are about two million years old as a type, and felines have been around in more or less their current form for well over three million years, with the same body types, dental features and other characteristics appearing, disapppearing and reappearing several times over.

Hell, there was even a completely different branch of creatures of the genus Nimravidae that looked like felines, but were not related to them at all unless you went back to about 55 million years ago or earlier. Those critters are so similar in body structure and other features that it's uncanny, because they evolved along the exact same lines to fill the same ecological niches as felines despite not being related. Shame the whole branch has gone extinct.

If you want more info on the felines and Nimravidae, read the book The Big Cats and their fossil relatives by Alan Turner. It's published by Columbia University Press.

Edi

[Darth Raptor]

A mammal species surviving 11 million years? Damn.

No, the article got it wrong. The Diatomyidae is a family, not a species. 3 million is about the upper limit on the lifespan of any individual mammalian species.

[defanatic]

I'm not doubting that, but why?

[Darth Raptor]

I'm not doubting that, but why?

Three million years is an extremely long time, brief only in the geological sense. In three million years a habitat will have likely undergone drastic changes several times. In that amount of time a species will have changed drastically as well, or gone extinct. Either way, the species in question isn't there anymore. The only other alternative is migration, but that presents a whole new set of challenges. The main reason reptilian species and such are longer lived is because they tend to be less-specialized into a given ecological niche.

At any rate, keep in mind the biological definition of "species"; only a tiny fraction creates a successful speciation, and a species is considered extinct even if it has living descendents (just like our ape-like ancestors are extinct even though we're still here).