BOZEMAN — Dinosaur expert Jack Horner says it's time to get past the idea that dinosaur bones are so precious that they should never be cut open.
Examining bones under the microscope is crucial to discovering how the creatures lived and evolved, Horner said Thursday.
Yet the idea persists among many museum curators and government agencies that cutting fossils is "destructive sampling."
Horner, curator of paleontology at the Museum of the Rockies, spoke to about 60 scientists from all over the world at the opening of the second International Symposium on Paleohistology - the study of fossilized animals under the microscope.
"Basically, what I'm saying is cut stuff up, cut up everything," Horner said. "Histology enhances your specimen's scientific usefulness. There's a tremendous amount of information inside. If we are to interpret the past world, we need this data."
By cutting thin slices of fossilized bone and studying them under microscopes, scientists can learn about animals' growth rates, age at death, what they ate, similarities to birds and find evidence in the debate over whether dinosaurs were warm-blooded.
"All the biological information is on the inside," Horner said.
When he began finding nests full of dinosaur eggs in Montana three decades ago, he said, "I was fortunate to find the first dinosaur embryo, because I cracked open the eggs."
For decades, curators would only release tiny fragments from their fossil collections for microscopic study. They wouldn't allow cutting into major bones, because of an attitude that "they're so precious, you can't open them up," he said.
"It's like having a Christmas present and never opening it. It's absurd," Horner said. "It's still precious, but you can open it."
Horner said the museum's dinosaur crews have dug up more than 100,000 fossils. After the bones are unearthed, they're cleaned up and pieced together, often like 3-D jigsaw puzzles.
It's during that preparation, he said, that chunks of bone are removed, molds of the chunks are made and plastic replacement pieces created. The plastic pieces are then inserted back into the fossils, painted to blend in and marked with yellow plastic tags. That lets scientists study the bone under a microscope, yet still put together the typical dinosaur skeleton seen in museums, without changing the length or shape of the fossil.
Horner appeared to be preaching to the choir, getting no negative comments from his audience. Other scientists were scheduled to present their findings on fossilized teeth, eggshells, soft tissue and bones sliced from mammals, birds, reptiles and dinosaurs.
Sarah Werning, a Ph.D. candidate in integrative biology from the University of California at Berkeley, said that the U.S. Forest Service was about to adopt regulations on preserving fossils that view histology as destructive sampling.
"We need to educate them," Horner said. "Specimens shouldn't be off limits as long as the recovery method is responsible."
Werning said later that paleohistology is emerging as an important subfield in paleontology. "It's opened up windows, allowing us a much richer understanding," she said.
The first International Symposium on Paleohistology was held in Barcelona, Spain, in 2011, and the next one will be held in Bonn, Germany. Horner said it's "wonderful" that the second symposium was held in Bozeman, where the Museum of the Rockies has the only dedicated paleohistology lab in the United States.
Among those in attendance was Armand de Ricqlès, the French scientist who once had the only paleohistology lab in the world, and who Horner visited decades ago in Paris to learn histology techniques.