Greg Aldrete at work in the dinosaur prep lab, using a dental pick to prize tiny pieces of rock away from delicate fragments of dinosaur rib bone. When fossils are fragile like this one, only careful and patient work with fine hand tools can remove the rock encasing the bone fragments without damaging the bone fossil itself. The final prepped and assembled bone may give little clue as to the hours that went into cleaning it, but a beautiful finished specimen is a source of great pride to the paleontological preparator who has transformed it into a valuable piece of evidence for the paleontologist.