Paleopathology is the study of malformations in the bones that may have been caused by disease or injury, and these malformations are often referred to as paleopathologies. There are basically two causes of malformations: trauma (injury) and disease.
Trauma or injury generally shows up as puncture wounds, unhealed breaks (which are difficult to distinguish from a break caused after death), and a healed break. Puncture wounds can be caused by the teeth of a predator. Skull bones tend to be thin, and can be easily punctured by teeth. The big cats and other predators often carry their prey by the head, and can leave tooth marks in the skull bones. Victims of sabre-toothed cats can be easily recognized by the large wounds left by their strong teeth. Paleoanthropologists (paleontologists who study early humans) sometimes find puncture wounds that might have been caused by arrow- or spear-heads.
Often, paleontologists will find bones that have been broken. These unhealed breaks could have been caused when the animal was alive, perhaps during a fight or because of a fall, or they might have been caused long after the animal was already dead, and perhaps even after the bones were fossilized. It is very difficult to determine whether the breaks happened while the animal was alive or after death (post mortem), so unhealed breaks really cannot tell us much about how the animal lived.
Paleontologists can also find bones that were broken, then partially or completely healed. This can tell us something about the animal's life: we know that it survived long enough after the initial break for the break to heal. Without prehistoric doctors to set broken bones, these breaks would generally heal unevenly, which could cause a limp if the break was in a foot or leg bone, and could result in other malformations in the bone. Most of these healed breaks would have occurred when the animal was fairly young, and could recover from a broken bone more easily; broken bones in older animals were more likely to lead to death.
