A good question. I have been working on dinosaur bones we dug up two summers ago. Recently I was excavating a large bony piece that had parts projecting out all over the place. I thought it would turn out to be a skull, but instead it was a thoracic vertebra, one of the most complex bones in the body. It has articulations (places that interact with other bones) all over it, and spines sticking out in every plane. It is about 18 inches high. A picture of it is available here. Much of the bone was very rotten and had to be reinforced with special glues. We use a product called Paleobond, which is a form of superglue that comes in a variety of thicknesses. The thicker glue is used to bridge places where bone is missing, and the thinner material is used to infiltrate the crumbly bone to stabilize and strengthen it. I was working on a narrow ridge of bone when my dental pick slipped and gouged out a piece of rotten bone. There was no way to replace the broken out material, so I just filled it with the thick glue after using the thin glue to penetrate and strengthen the ridge.
2010 Arthur V. Chadwick, Ph.D.