In 1898, according to legend, the Pennsylvania steel magnate Andrew Carnegie saw a newspaper story about great prehistoric monsters called dinosaurs. He scrawled a note: "Get one for Pittsburgh."
That is why Pittsburgh's Carnegie Museum of Natural History has one of the world's leading collections of dinosaur fossils.
The problem is that even though the newest of the dinosaurs are 65 million years old, scientists' understanding of them has been racing along, changing with each new find. So the Carnegie staff has decided to dismantle -- and rethink -- its entire collection.
Our image of dinosaurs comes mostly from what one finds in old sci-fi films -- big, lumbering creatures, dragging their tails on the ground. In recent years, scientists have decided they were probably much more energetic and agile -- and the way most fossils were displayed was wrong.
"Unfortunately, they don't come with instruction manuals," Matt Lamanna, a paleontologist at the museum, said with a smile. Skeleton by skeleton -- in fact, bone by bone -- he and his colleagues are overseeing the rebuilding of their dinosaurs.
We caught up with him in Paterson, N.J., in an old foundry that has now been converted into a dinosaur studio. The Carnegie dinosaurs have been shipped here, bone by bone, in carefully padded wooden crates.
In Paterson, a gentle dinosaur lover named Phillip Fraley oversees a small army of painters, sculptors, welders and former museum staffers, who are rehabbing the fossils under the scientists' watchful eye.
"These bones begin to dictate to you the way that they want to be put back together again," says Fraley, "the way they want to be lifted up or held."
Fraley, a longtime exhibit designer at New York's American Museum of Natural History, oversaw the rebuilding of the dinosaur collection there. He and his wife went into business for themselves, painstakingly assembling skeletons for museums from Chicago to Singapore.
"In mounting fossils you really see a process that began 100, 150 years ago," he said.
The scientists back then certainly had the best of intentions but not the best information. Very few of the fossil skeletons they dug up were complete, so they made educated guesses, sometimes based on their knowledge of other species.
"If you look at some of those old mounts," says Lamanna, "there are actually huge spaces between the vertebrae where they actually had to kind of 'disarticulate' them -- in other words, throw their backs out of joint -- to get them to fit together the way they thought they went."
Since then, they've found that a Tyrannosaurus rex probably had a tail a few feet shorter than most museums show -- and that many dinosaurs held their tails up in the air for balance.
By way of proof, Lamanna points out that the footprints of dinosaurs are fairly common. But if the dinosaurs really dragged their tails on the ground, there would probably be the fossilized remains of ruts behind the footprints. Scientists have searched and found places where a tail may have swished back and forth, but it appears a T. rex did not drag its tail.
"I'm not going to say there's never tail-drag marks found," Lamanna says, "but they're found so rarely that it really shows us, I think, pretty convincingly, that the dinosaurs held their tails aloft almost all of the time."
When the Carnegie museum in Pittsburgh opens its new dinosaur wing later this year, the skeletons will be posed as scientists believe they would have looked eons ago. Visitors will see meat-eating dinosaurs sparring over the carcass of a plant-eater. Small mammals -- which survived whatever killed the dinosaurs -- will be posed underfoot. There will be foliage, such as dandelions and sycamore trees, little changed over time.
And years from now, as the scientists learn more, they say they'll probably have to change the exhibits all over again.