No Bones About It.(Smithsonian National Museum of Natural History)(Technology Information)

TO CONSERVE A NATIONAL TREASURE, THE SMITHSONIAN REPLACES ITS TRICERATOPS SKELETON WITH A DIGITALLY ENHANCED REPLICA

The Smithsonian National Museum of Natural History (NMNH) is trying to prevent history from repeating itself. More than 65 million years ago, the three-horned, plant-eating dinosaur known as triceratops became extinct; today its fossilized remains are in danger of suffering a similar fate. After nearly 100 years of displaying the world's first triceratops skeleton, the museum was forced to disassemble the specimen and replace it with a cast replica to protect the fragile bones from further atmospheric wear and tear. While embarking on this major restoration project, the NMNH scientists also rewrote history by using a variety of digital technologies, including 3D scanning and stereolithography, to correct scientific inaccuracies in the original 1905 mounted skeleton.

For instance, the skeleton is a composite from at least 15 mostly similar-size triceratops dinosaurs. Using bones from different individuals is standard practice for even the most recently mounted specimens because finding a complete dinosaur skeleton is virtually impossible. Therefore, the museum's original preparators were forced to improvise when constructing the skeleton. Since no triceratops specimens had been found with feet, they substituted foot bones from a similar-size animal of a different species. The group also used a smaller skull as well as a mismatched left humerus (shoulder bone), which was smaller than the right, as were the left ilium (pelvis) and left scapula (shoulder blade) compared to their right-side counterparts.

Prior to the skeleton's disassembly in mid-1999, the museum contracted Scansite, a scanning service provider, to oversee the scanning of the fossils. This procedure would provide the scientists with a digital archive of the specimen before they replaced it with a replica made from casts of the original. Seizing a rare opportunity, the team also scanned most of the fossils individually once they were taken down from the mount.

According to Lisa Federici, cofounder of Scansite, the most ambitious step in the project, aside from the disassembly, was acquiring the 3D data. Once that was done, the door opened to a host of other digital applications, which were provided from various vendors free of charge or for a minimal stipend. "Scanning is the missing link that bridges the real world and the computer" she says. "And it's a perfect fit for dinosaur fossils, which have organic shapes that are difficult to measure by any other means without damaging the specimen."

Toy maker Hasbro was the first to offer its services, creating one-sixth scale models of the original fossils from the scan data, using an SLA7000 stereolithography machine from 3D Systems. The plastic-like models enabled the museum's paleobiologists to easily manipulate the miniature bone joints for testing theories about the dinosaur's range of motion, and helped the group determine a more accurate and natural position for the new mounted skeleton. Other companies in the rapid-prototyping industry helped create correctly sized replacements for the skull and certain bones. As a result of these efforts, this May the museum will unveil a new triceratops--made from light, durable casts--that is more anatomically correct in structure and posture than the original skeleton.

Digitizing the Dino