Chicago filmmakers Dave and Kathy Monk first met Jane three and a half years ago inside Rockford’s Burpee Museum of Natural History. Two tons of rock and desert dirt encased the dinosaur skeleton, which was fresh from a 66-million-year-old grave. Already, the bones had the paleontology community buzzing: could Jane be the most complete juvenile Tyrannosaurus rex ever discovered?

What science viewed as a mystery, the Monks saw as a ripe subject for a documentary. “We’ve seen Jane go from being a Nanotyrannus to a juvenile Tyrannosaurus rex, to a Tyrannus lancencis, to a Nanotyrannus and back to a juvenile T. rex,” says Dave Monk, who pegged the dinosaur as the subject most likely to elevate the profile of his Ravenswood Manor–based video company, Brave New Pictures. Over time, he befriended Burpee curator Michael Henderson, who in 2001 stumbled upon Jane’s bones during an amateur dig in Hell Creek Formation in southeast Montana. (In May, Hender-son returns there with another amateur group; for information, go to www.burpee.org.)

Soon Monk had an exclusive agreement that would allow him to produce the hourlong program, which premières June 9th at the Coronado Theatre in Rockford and airs this summer on the Science Channel. To amass enough material, the filmmakers traveled from Montana to Florida, gathering 60 hours of footage. Everyone pitched in, including the Monks’ daughters, Dina, now 13, and Julia, 11, who lugged equipment and squeaked out dinosaur sounds during animated scenes. “It was a great life experience for all of us,” Dave says.

As the family learned more about Jane and the Cretaceous period, the identity of the dinosaur herself was sparking disputes. One handful of scientists believe Jane to be the most complete juvenile T. rex ever found and a rare opportunity to understand growth patterns in the species. Another equally distinguished group of dinosaur experts contend that Jane is a Nanotyrannus-a separate, smaller carnivore whose very existence is hotly debated.

For his part, the man who discovered Jane, the Burpee’s Henderson, argues that the skeleton is a juvenile T. rex and has billed it as such at the museum. But even he admits to some doubt. “We’re only scratching the surface of what we can learn from Jane,” says Henderson, who continues to study the dinosaur’s bones and consult with experts.

Ultimately, the filmmakers decided that they didn’t have to pick sides: the controversy was the story, and the film the perfect medium to air the different arguments. In one early sequence, the renowned Wyoming paleontologist Robert Bakker tells the camera, “You guys at the Burpee Museum have the only good specimen ever found of Nanotyrannus.” To which another equally respected dinosaur expert, the Museum of the Rockies’ Jack Horner, replies, “I think most people have pretty much come to the conclusion that it’s a juvenile Tyrannosaurus.” Concludes the Burpee’s Henderson, on tape: “Well, at least we all agree it’s a dinosaur.”

Kathy Monk says all the uncertainty of the Jane project made one key element of documentary filmmaking come easy: choosing the title. At Kathy’s suggestion, the family named their movie The Mystery Dinosaur. Everyone agreed on that.