Marko Djurica / Reuters

People look at the skeleton of a mammoth at an open-pit coal mine in Kostolac 62 miles southeast of Belgrade on June 27.

What started out as a coal mine near the Serbian town of Kostolac, southeast of Belgrade, has turned into a gold mine for mammoth bones. Archaeologists say they've found the remains of at least five of the ancient beasts, scattered across 20 acres of sandy terrain.

"There are millions of mammoth fragments in the world, but they are rarely so accessible for exploration," Miomir Korac of Serbia's Archaeological Institute told The Associated Press. "A mammoth field can offer incredible information and shed light on what life looked like in these areas during the ice age."

Experts have been finding mammoth remains at the open-pit mining site for years. In 2009, a well-preserved, 16-foot-long mammoth skeleton was discovered about 89 feet (27 meters) beneath the surface. That specimen, nicknamed Vika, was a furless southern mammoth that lived about a million years ago. Another mammoth skeleton, thought to be 500,000 years old and nicknamed Kika, was found at a factory site in northern Serbia in 1996 and is now on display at a museum in Kikinda.  

The more recently discovered bones, excavated last month at a depth of about 66 feet (20 meters), appear to be from woolly mammoths that lived tens of thousands of years ago.

"This discovery is interesting because, unusually, there are many bones in one place," Sanja Alaburic, an expert from Serbia's Museum of Natural History, told AP. He speculated that the bones were carried to the site by flooding.

Korac said that colleagues in France and Germany have been contacted for consultation. Unearthing all the bones will require at least six months of work, he said.

Marko Djurica / Reuters

Archaeologists work to find mammoth bones at an open-pit coal mine in Kostolac, 62 miles southeast of Belgrade on June 27.

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Russian and South Korean scientists, including the cloning expert who was the focus of a stem-cell scandal six years ago, have signed a deal to try re-creating a woolly mammoth using cells recovered from 10,000-year-old frozen remains.

The papers for the joint research project were signed on Tuesday by Hwang Woo-Suk, chief technology officer for South Korea's Sooam Biotech Research Foundation; and Vasily Vasiliev, vice director of Russia's North-Eastern Federal University, during a ceremony at Hwang's office in Seoul.

Hwang is infamous for his role in human embryonic stem-cell research: In 2004 and 2005, he and his colleagues claimed to have extracted stem cells from what they characterized as the world's first cloned human embryos. But in late 2005, his work was found to have been based on fabricated data, and he was barred from continuing research with human cells.

Despite the disgrace, Hwang continued working with animal cloning techniques. Before the scandal broke, his team announced that they produced the world's first cloned dog, nicknamed Snuppy, and that claim has stood up to scrutiny. Last October, Hwang's team at Sooam unveiled eight cloned coyotes that had been produced by injecting nuclei from coyote skin cells into dog eggs. At the time, he said he was interested in cloning an endangered African dog species known as the lycaon ... and was interested in cloning a mammoth, too.

In December, Japanese news media said that scientists recovered a seemingly viable sample of bone marrow from a frozen mammoth thigh bone in Russia's Sakha Republic, and that a mammoth could be cloned back from extinction within five years. This week, Agence France-Presse reported that North-Eastern Federal University is working with the Japanese scientists and with the Koreans. The Beijing Genomics Institute is said to be taking part in the Korean-Russian project as well.

Reports from Seoul suggest that the mammoth-cloning effort could be launched this year if the Russians can ship the remains to Sooam's laboratory. "The first and hardest mission is to restore mammoth cells," a colleague of Hwang's at Sooam, Hwang In-Sung, told AFP.

Jung Yeon-Je / AFP - Getty Images

South Korean scientist Hwang Woo-Suk, (far left) and Vasily Vasiliev, vice director of North-Eastern Federal University of Russia's Sakha Republic (far right), exchange agreements during a signing ceremony on joint research at Hwang's office in Seoul on Tuesday.

Sooam Biotech Research / AFP - Getty Images

This diagram released by the Sooam Biotech Research Foundation shows the process of replacing the nuclei of elephant egg cells with those taken from the mammoth's somatic cells to bring a mammoth back to life.

The plan calls for extracting nuclei from the thawed-out mammoth cells, putting them into elephant egg cells and stimulating the cells to start dividing. Embryos would be implanted into elephant wombs for gestation — and if the effort is successful, a mother elephant would give birth to a baby mammoth around 22 months later.

That's a big "if," as I wrote in December when I discussed the Japanese-Russian project. In addition to the usual problems surrounding interspecies cloning, it's highly doubtful that genetic material recovered from tissue that's been frozen for millennia would be sufficiently intact for extraction and implantation. What do you think of Hwang's chances? Feel free to register your vote at right, and voice your opinion in the comment section below.

More about mammoths:

• Clone a mammoth? Not so fast
• Mammoths mated with a different elephant species
• Mammoth resurrection on the way?
• Woolly mammoth's DNA mapped

Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

Reports from Japan suggest that long-extinct woolly mammoths could be cloned back into existence within five years, but don't hold your breath.

"C'mon, it'll never happen. Not in my lifetime," said Webb Miller, a Penn State computer scientist and genomicist who helped decipher the genetic code of a woolly mammoth.

Japanese and Russian researchers have been working for years to find a suitable woolly mammoth specimen in the Siberian permafrost, and they recently told Japan's Kyodo news service that they recovered what they hope will be viable bone marrow from a frozen thigh bone recovered near Batagay in eastern Russia's Sakha Republic (a.k.a. Yakutia).

Their plan is to take the nuclei from bone marrow cells, transplant them into egg cells extracted from elephants, and implant the cloned embryos into the wombs of mama elephants for gestation. This is the technique that has given rise to cloned mammals ranging from Dolly the sheep to pigs, cats, dogs and monkeys.

Kyodo's report says "there is a high likelihood" that biologically active nuclei can be extracted from the frozen marrow. Researchers on the case include Russian experts from Yakutsk's Mammoth Museum and Japanese biologists from Kinki University in Osaka Prefecture. Kyodo said a full-fledged joint research project would be launched next year.

Woolly mammoths haven't walked the earth for thousands of years, but the idea of resurrecting the species seems to have a powerful hold on the collective psyche. Some folks have even talked about setting aside a "Pleistocene Park" for mammoths and other Ice Age animals.

Miller, however, isn't buying it.

"DNA from a woolly mammoth is a mess," he explained. "It's fractured into very short pieces, and there's a lot of postmortem DNA damage other than just breakage. The code gets damaged a lot."

Even if the DNA is intact and the nuclei are successfully merged with elephant egg cells, the success rate for cloning animals — and particularly extinct and near-extinct species — is not good. Generally speaking, there are scores of failures for each successful pregnancy brought to term.

A couple of years ago, scientists succeeded in producing a Pyrenean ibex from tissue that was taken from the last representative of the subspecies in 1999, but the cloned progeny survived for only seven minutes. Attempts to clone an Asian gaur didn't end much better. Australian researchers had to scrap plans to clone the Tasmanian tiger back from extinction, although they later succeeded in transferring part of a Tasmanian tiger gene into mouse embryos.

These cases suggest that there's not much of a chance of re-creating the mammoths. Genetic engineering may eventually produce a "hairy elephant" with mammoth-like characteristics. But a creature genetically identical to the behemoths of the Ice Age? "If somebody does that, I will eat my hat," Miller said. "And I'll wonder why they did it."

Miller said studying the DNA of long-extinct species has value, even if the efforts don't result in a resurrection.

"I'm looking out my window, and 13,000 years ago, there were some really interesting animals out there," he mused. "They're gone now, and I'd like to know why. ... Understanding which species survived and which ones didn't, looking at their genome and trying to figure that out, that's interesting to me."

But when it comes to living, breathing animals, "I'm personally more interested in keeping the species we have," Miller said. "I'd like to keep tigers around for a while."

Despite Miller's qualms, the quest to re-create the woolly mammoth could well continue for the next five years or longer. And that's not all. Paleontologist Jack Horner is moving ahead with his plan to modify chicken DNA and make the barnyard birds look more like the dinosaurs they descended from. Dino-chickens vs. woolly mammephants? That sounds like a great plot for the next "Jurassic Park" sequel. ... 

More about mammoths:

• X-ray scans reveal baby mammoth mysteries
• Dog skull found with mammoth bone in mouth
• Mammoths mated with a different elephant species
• Mammoth resurrection on the way?
• Woolly mammoth's DNA mapped

Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

The long-extinct woolly mammoth could be resurrected within five years, thanks to recent advances in cloning technology.

Japanese researchers plan to collect mammoth tissue this summer from a carcass that was frozen in the Siberian permafrost and is now in a Russian research laboratory, according to a report in the Yomiuri Shimbun.

The hope is to recover an undamaged nucleus of a mammoth cell from this tissue and insert it into an elephant egg cell from which the nucleus has been removed. This will create an embryo with mammoth genes, according to the news report.

This embryo will be inserted to the elephant's womb in hopes that she'll give birth to a mammoth.

"Preparations to realize this goal have been made," Akira Iritani, a team leader from Kyoto University, told the Yomiuri Shimbun.

New technique
Previous attempts to recover nuclei from frozen tissue failed because the cold temperatures damaged the DNA.

The new technique is based on work by Teruhiko Wakayama of the Riken Center for Developmental Biology, who in 2008 cloned a mouse from the cells of another mouse that were frozen for 16 years.

Iritani says his team has devised a method to extract the nuclei of mammoth cells without damaging them. "Now that the technical problems have been overcome, all we need is a good sample of soft tissue from a frozen mammoth," he told London's Daily Telegraph.

Mammoth for display
If the team is successful in creating an embryo, they will discuss how to breed the mammoth — and whether or not to display it to the public — before transplanting to a surrogate elephant, Iritani told the Yomiuri Shimbun.

Even if the embryo is successfully created and implanted, the chances of bringing a cloned mammoth to term (or any cloned animal, for that matter) are slim. When South Korean researchers tried cloning dogs, for example, nearly 1,100 embryos were transplanted to surrogate dogs, but only two live births resulted, and only one of those puppies survived past the 22-day mark. 

Nevertheless, Iritani was confident of success. "After the mammoth is born, we'll examine its ecology and genes to study why the species became extinct and other factors," he said.

Woolly mammoths went extinct at the end of the Ice Age, about 10,000 years ago. Scientists have long debated whether climate change or human hunters were the cause of their demise.

Last December, researchers said another factor could be the fact that the creatures delayed weaning their young due to the long dark winter north of the Arctic Circle.

More about mammoths:

• Woolly mammoth's DNA mapped
• Mammoth blood revived by bacteria
• Ice Age baby mammoth goes on display
• Scientist sets out to re-create Ice Age park