Passage IV

NATURAL SCIENCE: This passage is adapted from the article “Digital Dinos Get Real” by Josh Fischman (©2002 by U.S. News and World Report).

There are about 250 bones stamping around inside Ralph Chapman's computer. They belong to an 18-foot-long horned dinosaur that had been taken apart by a museum. On Chapman's screen, the bones have been pieced together to form a moving, skeletal triceratops: Bone-white limbs stride below fleshless hips, shoulders, and skull.

But not directly below the shoulders. As Chapman, a paleontologist at the Smithsonian Institution in Washington, D.C., points out, the forelimbs are splayed out to the sides a bit. For years, triceratops reconstructions had the limbs right under the body. But when the limbs were digitally scanned in three dimensions and assembled into scaled-down computer models, there was no way they could fit.

The virtual triceratops一returned to full size in computer-sculpted plastic—debuted in 2001 at the Smithsonian's National Museum of Natural History. “Nothing can replace having the real thing in your hand,” says Rolf Johnson, director of exhibits at The Wisconsin Lake Schooner Education Association. “But computers let you do things that are difficult with such large bones, like making them take a step."

Johnson should know. Nearly a decade ago, using ropes, pulleys, and a gantry that nearly reached to the ceiling, he strung together limb, shoulder, and chest bones of a triceratops relative and tried to make it walk. "We used fiberglass casts of the bones, but they were still really heavy. It was like putting a 50-pound bag of cement on a pulley.'' Every time they wanted to try a different arrangement, they had to readjust the whole contraption.

Chapman’s group, faced with bones from a dino that weighed about 6 tons when alive, decided to avoid such heavy lifting. In 1999 Smithsonian scientists were dismantling the triceratops exhibit, because the fossilized bones were rotting. After each bone was removed, researchers ran a laser scanner over it, capturing thousands of digital points that represented the bone surface.

Software expert Art Andersen then played an elaborate version of connect the dots, filling the spaces in between the points to re-create each bone. Researchers used them to produce two detailed model skeletons. One took shape in a computer. The other model was made by feeding the same data to a machine that carves parts for prototype toys; this time it turned out a miniature triceratops, one sixth the dinosaur's actual size.

With both models, Chapman and other paleontologists used ridges on the bone, which indicate where muscles were once attached, to figure out how the limbs were anchored to the shoulders. "No matter how we tried to put them right underneath, it didn't work. The muscle would have to go in very weird directions," Chapman says. But with the elbows and feet pointed slightly away from the body, the limbs could move easily.

So triceratops could scoot along, but not at breakneck speed. A plant-eating dinosaur unable to gallop away from hungry carnivores would need to use its head to survive. Literally. Paleontologists had thought the massive head would be hard to whip around to repel an attacker. But the plastic model showed the skull and neck connected at a smooth swivel joint. "It isn't until you hold it in your hands that you can feel how easily it moves, it's perfectly balanced, and you can point the horns in any direction," says Chapman. "It actually gave me goose bumps the first time I did it, because no one knew about this.” It makes sense, he continues: If you can't run away, you need good protection.

Kent Stevens of the University of Oregon has been examining the long necks of plant-eating sauropods. Such necks stretched as much as 40 feet in length, leading many scientists to assume these giant vegetarians were grazing in the treetops. That's not what Stevens found after plugging the actual measurements of the neck bones into a computer program. These bones link with ball-and-socket joints, and if they bend up too much they simply come apart; the neck would have collapsed. A more likely scenario is that those necks were used to plunge horizontally deep into the forests or dip down to riverbanks in search of food.

Stevens notes such programs are still just supplements for bone hunters. But as the software gets more sophisticated, the dinosaurs produced get ever more realistic. Chapman's group, for instance, next plans to add muscles and ligaments to its animated skeleton. "If it starts to walk and ties itself into knots, we'll know we've done it wrong. And then we'll start over again,” he added.