Bones break and so do teeth, but they are more likely to be broken after death and fossilization than when alive. Erosion usually uncovers fossils. Then freezing, thawing, running water, wind and gravity break them up. Many fossil finds contain broken fossils which must be pieced together again. One of the jobs of a paleontologist is to take all the fossil bits found in a field site and see if they were once together and how they can be glued back together.
