Fossil sales fueled paleontology for over 100 years, beginning with "The Great Dinosaur Rush." During those 19th century Bone Wars, two rival paleontologists –– Edward Drinker Cope and Othniel Charles Marsh –– raced to find the greatest number of dinosaurs in the West, uncovering fossils themselves and also purchasing them from commercial fossil hunters. Today, if you visit the nation's largest museums, you are likely gazing upon bones that were dug up by fossil hunters and then bought by legendary philanthropists like Andrew Carnegie and George Peabody. But the rivalry between Cope and Marsh may have also helped taint the reputation of bone prospecting. In their haste to outdo each other, the two made mistakes –– for example, Marsh put the wrong skull on an Apatosaurus and designated it a new species, Brontosaurus –– and they were so protective of their digging sites that they'd hurriedly bury them afterwards, sometimes destroying other fossils in the process.

Some paleontologists believe commercialism still has an important scientific role to play, though, because digs are notoriously time-consuming, expensive and require significant manpower. Fossils need to be found and excavated at the rate they are being exposed to the elements so that they're not lost, says Mike Triebold of the Colorado-based dealer Triebold Paleontology Inc., which often supplies museums.

It's in the best interest of commercial companies to be stringent data collectors so they can sell to quality museums, Triebold says. He believes data collection by commercial operations can be superior to that done by academic institutions strapped by budgets and bureaucracy. "People that have those extreme views are preventing a spectacular pair of fabulous dinosaurs with a tremendous amount of science attached to them from going to a proper repository," he says.

But a growing academic circle has increasingly shunned any fossil sales, says Bakker. "The attitude toward independent, and I like to call them independent collectors, changed. Now they were considered pirates, brigands and buyers."

The change is often attributed to the much-publicized 1997 auction of "Sue," a South Dakota T. rex that highlighted the monetary value of fossils. After 10 minutes on the Sotheby's auction block, Sue sold for $8.4 million to Chicago's Field Museum of Natural History. The museum was able to acquire Sue only through the financial support of big corporations, including McDonald's and Disney.

The legal fight preceding Sue's auction included a federal court ruling establishing that fossils on private land were property that could be bought and sold. This exasperates scientists such as UC Berkeley paleontologist Mark Goodwin, who says fossils represent Earth's natural history and therefore belong to everyone. "In the United States, there are still some things you can't own," Goodwin says. "You can't own navigable waterways, you can't buy and sell body parts, but we are (one of) the only developed countr(ies) on the planet that doesn't have any regulation in regards to our fossil heritage on private lands."

Shortly after Sue's sale, Goodwin says, UC Berkeley got a bitter taste of what fossil greed can lead to when a T. rex jaw was stolen from its collection. FBI agents traced the jaw to Germany, a long journey that began after a student smuggled it into commercial hands.  "At the same time that the commercial market is driving theft and the dotcom boom is going on, you have eastern Montana, where some of these ranchers are barely making a living and all they see are dollar signs," he says. He's dismayed by the asking price of the Dueling Dinosaurs, given that the National Science Foundation's average annual budget for dinosaur research grants is about a half-million dollars. "I don't have $9 million. And for anyone who does, it is just preposterous and obscene to ask for that much money."

Some scientists have come to view the Dueling Dinosaurs, asking that their visits be kept secret. But Goodwin, like Horner, refuses to look at the fossils despite their significance. "It is hard as a scientist not to want to see the material that is in private hands," he says ruefully, "but you have to draw the line somewhere."

Chris Morrow at CK Preparations, expecting controversy, sought advice from Peter Larson of South Dakota's Black Hills Institute. Larson is a degreed paleontologist who straddles the commercial and academic worlds by both selling fossils and publishing on specimens in repositories. He's been in commercial fossil sales for decades and was one of the discoverers of T. rex "Sue."

His many publications are accepted within the academic community, although Horner argues they represent a conflict of interest. Larson, who is working on his Ph.D. at the University of Manchester, England, says he is studying overseas because opinions on commercialism are not as extreme outside the U.S.

Once Larson decided that the Dueling Dinosaurs provided "definitive proof of Nanotyrannus," the topic of his thesis, he sought to ensure that the specimens went to a recognized repository. The study of fossils is subject to policies such as those laid down by the Society of Vertebrate Paleontology, which publishes the premier dinosaur journal, Vertebrate Paleontology. The society's code of ethics stipulates that specimens on which papers are published must be held in a recognized repository; they cannot be located in private collections where their future is uncertain. The rules are meant to ensure a specimen's availability so that scientific conclusions can be verified. However, a lengthy approval process is needed before museums are considered repositories, and not all museums meet the requirements. The state of Montana has only one government-approved  repository, the Museum of the Rockies.

Even Larson was surprised at the fossils' bitter reception from museums. He had hoped to interest his alma mater, the South Dakota School of Mines and Technology. Because he knew the school's museum could not afford the dinosaurs, Larson offered to connect the institution with a philanthropist who could donate them. The response was peremptory. "SDSMT is not interested in obtaining the specimens by purchase or donation," wrote then-President Robert Wharton to Larson, in a letter dated Dec. 16, 2011. (Wharton, who declined to comment on the correspondence, died in fall 2012.) Larson was shocked that the school would refuse a multimillion-dollar donation of groundbreaking specimens. "It's almost like a religious belief," Larson says. "It has nothing to do with reality or morality or anything else. How can you divorce yourself from private commerce? It drives the world."