Tucson, Arizona

Happy hunting ground: A fossil elephant skull, for sale in Tucson. Credit: REX DALTON

The Gem, Mineral and Fossil Showcase of Tucson, a city-wide street fair of international artefacts, is a major marketplace for fossils, many of which, some claim, have been smuggled out of China and other countries.

Chinese bird fossils from the early Cretaceous that have yet to be described, ancient skulls of rhino and ivory-tusked elephant, and dinosaur eggs were all on sale at the annual two-week event that ended last week.

Some of the dealers selling Chinese fossils say they have documents showing they were legally exported. But US and Chinese scientists say the papers are irrelevant, as the specimens are Chinese cultural treasures.

US customs officials say that the importation, possession and sale of a smuggled specimen may violate various federal laws. But an in-depth legal analysis of each case is needed to determine if a criminal offense was committed, says Customs Special Agent Lisa Fairchild in Washington DC.

About 3,000 dealers — mostly selling gems and minerals — sell their wares in hotel rooms, on patches of ground and in huge tents. Dinosaur eggs and rhino skulls could be found among some of the 24 individually operated shows in Tucson, but this year most of the questionable Chinese fossils were being sold at a show held in a converted hotel .

Chinese fossils large and small were displayed throughout the hotel. One room contained boxes of dozens of dinosaur eggs stacked like eggs in a supermarket.

It was in this setting that that dinosaur enthusiast Stephen Czerkas organized the purchase last year of the controversial bird fossil that found its way into the National Geographic magazine last November (see main story).

Czerkas refuses to say who sold the fossil for $80,000. He says that, after he had found it, a patron went to Tucson to buy the fossil for the small Dinosaur Museum in Blanding, Utah. But the museum's main patron, Dale Slade, says that Czerkas went to Tucson and bought the fossil himself.

Timothy Rowe, a University of Texas palaeontologist who has analysed the fossil, visited Tucson this year to investigate its source. While there he met dealers such as Zhouping Guo, a water-company geologist who runs the company Sin-Am Bridge out of his home near San Diego, California.

Rowe says that Zhouping knows Czerkas and that during Rowe's visit he produced three Chinese bird fossils that appeared to be species not yet described in the scientific literature.

Zhouping denies selling Czerkas the fossil. He says that he has documents from a Chinese museum proving his specimens were legally exported for scientific exchange, although he refused Nature's request to inspect the documents.

Martin Zinn, who ran the show that included independent firms like Sin-Am Bridge, says he prohibits dealers from selling smuggled or illegal goods, that Sin-Am insisted its specimens were properly documented, and that all was “normal”.

A spokeswoman for the Metropolitan Tucson Convention and Visitors Bureau, which organizes the showcase, says the organization knew nothing of illegal sales and was not responsible for independent dealers.