Maybe we should blame Steven Spielberg. For years, private land- owners in the US have co-operated with scientists wanting to dig up dinosaur fossils on their property. But the laws of demand and supply hit science, too. After the "life on Mars" announcement in August 1996, prices of meteorites - any meteorites - multiplied by a factor of 10. And last month a record $8.4m (pounds 5.25m) was paid at a public auction for a Tyrannosaurus rex fossil. As a consequence, some US landowners are seeing dollar signs when hopeful scientists turn up for a dig.
"The sale shows that dinosaurs are wonderfully popular, and that is good for the science. But it is a double-edged sword," said Blaire Van Valkenburg, a professor of paleontology at the University of California in Los Angeles.
Dinosaurs, long popular among children, have only recently entered the realm of popular culture, aided by the film and book Jurassic Park and its sequel, The Lost World. But as the demand for fossils has increased, so has the competition faced by scientists from commercial collectors.
In the US, federal law allows only scientists to excavate vertebrate fossils on the half-billion acres (200 million hectares) of land owned by the US government. Most vertebrate fossils are found there. But commercial collectors are free to prospect for old bones on private ranches and farmland, and in some cases valuable fossils lie there too.
Last September in Hell Creek, Montana, the FBI was called in to stop relatives of a former landowner from using heavy equipment to excavate a T. rex site which lay in land taken over in a disputed foreclosure. The owners had fallen into debt; their assets, including the land, were seized.
The fossil had been discovered by Keith Rigby, a paleontologist at the University of Notre Dame. He thought it could be the largest T. rex skeleton ever found, or even evidence of a new species of dinosaur. But when he returned to the site after the unauthorised excavation, he discovered that two-thirds of the left side of the skull was missing.
Two of the missing pieces were returned anonymously, and members of the former landowner's family insisted that they had not removed anything from the site. But the case remained murky; the charity Earthwatch, which had helped fund Dr Rigby for nine years, was worried that the bones had been taken to sell to private collectors, who will pay thousands of dollars - or pounds - for them. But removing the bones from the ground confuses the issue of which animal they belonged to. Hell Creek was a river channel about 66 million years ago; bones found at the site could belong to dead animals that were washed into the channel, where they gathered. Piecing them together is no trivial task.
However, the theft that did occur is likely to be the thin end of a commercially- inspired wedge. "I would be very surprised if in the next five to 10 years we didn't see a lot more damage done," Van Valkenburg said.
In part, the success of dinosaurs in attracting people to museums may be their downfall - again. The Chicago Field Museum of Natural History was the auction buyer of the T. rex fossil, nicknamed Sue (after its discoverer, marine archaeologist and paleontologist Susan Hendrickson). That could now put the cost of digging on private land out of the reach of most academics, according to members of the Society of Vertebrate Paleontology, who recently held their annual meeting.
John Horner, the inspiration for the paleontologist hero of Jurassic Park (and an adviser on both films) says at least a dozen ranch owners with whom he has worked for years have recently started demanding money in advance before he can start looking on their land.
In some instances, landowners have asked museums to return fossils they were previously willing to donate to science, said Larry Flynn, an executive member of the paleontology society and president of Save the Fossils for Everyone.
And, of course, media coverage of such sales pushes things along, too. "My phone has not stopped ringing since the articles came out," says Allen Graffenham, a commercial fossil dealer who heads Geological Enterprises in Ardmore, Oklahoma. "It sends a message to landowners that they have something valuable on their land, and they are going to be reluctant to let university people on their land unless they pay."
However, he doesn't see this as a threat to science. "There are so many billions of fossils in the ground in North America, I don't believe for one minute that they are a limited resource," he said.
Well, perhaps. The problem, according to Lou Jacobs, president of the paleontology society, is distinguishing between the many common invertebrate fossils and a few rare vertebrate ones. That requires a certain amount of expertise. And while the society is concerned about excavations of private land, it is more worried about the future of federal land.
Last year, legislation was proposed in Congress to allow commercial collectors on to public land. It never got beyond the committee stage, but Dr Jacobs warned that pressure to change the law would increase as the stakes became higher.
Horner, who heads the Museum of the Rockies in Bozeman, Montana, firmly opposes the idea: "There is no reason for species which already belong to the public to be taken out and sold back to the public." But he does fear that Sue's record sale will give people the idea to go digging for their own dinosaur fossils. That, though, would ruin a precious resource.
Horner, who started his career as an amateur dinosaur hunter, says his museum regularly works with volunteer enthusiasts to dig up fossils. Such a partnership yielded the museum's own T. rex fossil, discovered by Kathy Wankel in eastern Montana in 1989 while her husband was fishing. However, without expert supervision, amateurs can damage rare fossils and all the clues they contain about a largely extinct world.
"The most important time for a fossil is when it is still in the ground," Horner says. "Once it is taken out, it loses its scientific context." But, as any poacher will tell you, an animal in the ground is worth a lot more once you get your hands on it.Reuse content