It is the dinosaur version of grave robbing: fossil poachers plundering a paleontological dig, frequently smashing ancient skulls and stealing valuable teeth, claws and feet.

Often, all that remain are shards of fossilized bone and a wrecked, irreplaceable scientific record. And in cases where poachers excavate an entire skeleton and spirit it away to illicit entrepreneurs or collectors, it is as if the bones, buried for millions of years, were being dug up only to be hidden away again in private collections.

"This is huge," said Catherine A. Forster, a paleontologist at George Washington University in Washington, who is head of the Society of Vertebrate Paleontology. "It isn't just one or two specimens. A fair proportion of very good fossils just disappear from knowledge, and few are ever seen again."

And while some scientists hoped that a high-profile legal case in New York last year over the $1 million sale of a rare Mongolian dinosaur would curb the illegal digging, that does not appear to have happened. Mark A. Norell, chairman of paleontology at the American Museum of Natural History in New York, said a visit to the Gobi Desert over the summer made clear that poaching continues "in a big way."

Philip J. Currie, a paleontologist at the University of Alberta in Edmonton, says he has determined that 98 skeletons of the dinosaur Tarbosaurus bataar (sometimes called Tyrannosaurus bataar) were destroyed or removed by poachers in Mongolia. Fewer than a dozen are in scientific hands, he says. And he has counted many other plundered fossil skeletons from the Gobi, including 86 ostrichlike dinosaurs. (It has been illegal to remove fossils from Mongolia since the 1920s.)

Although the age of the dinosaurs lasted about 165 million years, their skeletons are relatively uncommon: only about 3,000 are known to exist. About 1,300 dinosaur species have been identified, Dr. Norell said - more than half from a single skeleton and a third from a single bone.

Paleontologists are calling for the various laws on dinosaur stealing and smuggling to be enforced and tightened around the world, and they are pleading with private collectors to demand proof of a fossil's origins before they buy.

Otherwise, the scientists say, information will be lost forever about exactly where the fossils were found, what geological formation the creatures were in, how they were discovered and what surrounded them at death.

"I'm saying, 'Ask for provenance,' " Dr. Norell said."It worked in the art world.

The modern-day fossil rush began in earnest after the Field Museum in Chicago paid $8.36 million in 1997 for Sue, the most complete T. Rex skeleton ever found, said Kenshu Shimada, a professor at DePaul University in Chicago. Shortly after, the phenomenon of online buying and selling through sites like eBay took off, opening up global markets for fossils.

Dr. Shimada said the society became so concerned about the extent of the illegal dinosaur trade that it made a survey of "paleo hot spots," gathering information from 20 countries about where fossils are, what laws govern them and how the laws are enforced.

Dr. Currie said the Nemegt Basin in the Gobi Desert is a particular concern. It is one of the two best dinosaur sites on the planet, he said, with a diverse range of fossils and thousands of footprints. "One of the most spectacular sites for understanding dinosaurs in the world is now being destroyed by poachers," he said.

While the Mongolian government's successful lawsuit over the T. Bataar skeleton did not end poaching, it has had other effects. The sale was voided, and the smuggler, Eric Prokopi, a fossil dealer from Florida, awaits sentencing. The skeleton was returned to Mongolia in May.

As a result, the country has set up its first dinosaur museum.

The New York Times

(China Daily 11/03/2013 page11)