Realizing the significance of his find, Phipps sought help from CK Preparations, a nearby commercial company run by preparator Chris Morrow and paleoartist Katie Busch. The CK team became stakeholders, and eventually the multi-ton blocks containing the fossils, jacketed in plaster, were moved to its facility.

"The matrix in the jackets is pure sand," Morrow says, "which is really rare for skeletons. This layer is about 17 feet thick of nothing but sand, with no vegetation in it. So a massive pile of sand was dumped all around these graves." Perhaps the animals sank in quicksand; perhaps they were buried by collapsing cliffs. It's up to the scientists to decipher the story -- provided they get the chance.

To find predator and prey fossilized together is rare. The Dueling Dinosaurs are also preserved in three dimensions, not flattened by burial like so many skeletons. Fossil preparation has exposed about 30 percent of the specimens, enough to display interesting details. They are interwoven, with the elephant-sized ceratopsian in a near-standing position and the polar bear-sized tyrannosaurid underfoot. Both dinosaurs are articulated, meaning their bones are connected, from nose to tail-tip. They are so well preserved that some soft tissue patterns, like skin, are visible to the naked eye. Other sections expose shiny licorice-black bone.

The tyrannosaurid appears to be missing 22 teeth; 14 teeth have been found embedded in what were the ceratopsian's fleshy areas and one in its neck vertebrae. Tyrannosaurids shed teeth like sharks, and replaced them just as quickly. In this case, though, some teeth are broken in half, which Morrow believes indicates an aggressive fight. And the tyrannosaurid may have gotten the worst of it –– a crushed skull and cracked-open ribcage.

Despite the find's rarity, some paleontologists, like Horner, a once-casual Montana fossil hunter who now has honorary doctorates, say a serious study of the fossils would be pointless because they were excavated by amateurs.

Fossil excavation is a long, complicated process when done properly: It's common to remove specimens in plaster jackets, for example, including blocks of the rock "matrix" surrounding the bones. Just enough bone is exposed to reveal the dimensions of the creature, and then the surrounding rock is carefully cut to free the block. This can preserve sediments containing essential scientific evidence about the burial environment and the bones' original in situ position. Some scientists painstakingly document the exposure of each find, using time-lapse photography, laser mapping and soil samples taken every few centimeters.

Because the Dueling Dinosaurs were excavated with less sophisticated methods and without an academically trained eye to oversee the site, Horner and other critics say the bones have lost their scientific potential. Burial reconstruction -- analysis of the surrounding material and the position of the bones to determine the circumstances of the dinosaur's death -- is impossible, he says, since the dinosaurs were removed from the surrounding stratigraphy, the layers of rock above and below them. Because the overlying layers have already been excavated away, any scientist who wants to do a burial reconstruction would have to access the private land and use photographs to infer where the dinosaurs were located in the layers of rock.

"I have seen some information on the Dueling Dinosaurs," says Horner, "but it lacked the data that would allow the specimen to be described in rigorous scientific detail. Unless (such a) study had been accomplished at the site prior to it having been excavated, it is not possible to say anything about their behaviors prior to death." Although he is a leading researcher of tyrannosaurid bone structure, he has no desire to even see the specimen that may settle the Nanotyrannus debate.

Horner strongly opposes commercialism and believes scientists ought to avoid any association with it. "Commercial collectors say all sorts of things about the fossils they are trying to sell," he says. "The more extraordinary they can make it sound, the more money they think they can get. It is simply a sales pitch."

Bakker, Horner's longtime colleague from Houston, says the excavation and documentation of the Dueling Dinosaurs are excellent and that criticism of the find is simply bias against commercial collectors. He has looked over the photos and sketches the group collected during excavation, and says the burial site can be revisited for more information if needed. Most importantly, he says, the dinosaurs are still in the blocks they were excavated in, so that they retain their original positions and the sediments surrounding them.

He says there is evidence that the dinosaurs dueled to the death in a fight so violent that the carnivore's teeth were cracked out of its jaws. The fossils contain the "smoking tooth" of dinosaur behavior, demonstrating the way two species interacted, he says, and should be studied. "It is bizarre that strong opinions would be expressed by people who haven't seen it," says Bakker. "I went and I saw it. I didn't believe that they were dueling. I didn't believe that one had killed the other until I spent five hours with the specimens. And oh, yeah, they killed each other."

Horner and Bakker have been charismatic leaders in dinosaur paleontology for decades; each inspired a character in Steven Spielberg's Jurassic Park movies. They also have a history of bickering over the prehistoric meal selections of T. rex (Horner sees it as a scavenger) and the identification of Nanotyrannus (which Horner thinks is a juvenile T. rex). But their perspectives on the Dueling Dinosaurs represent just a fraction of the larger, fiery debate about commercial paleontology.