Interestingly, herbivorous dinosaurs show very few healed fractures - some broken sauropod ribs and a tail are rare examples. On the other hand, carnivores tend to have quite a few as they led a more violent lifestyle. These could be from trying to hold down struggling prey or through violent courtship and mating battles. Some dinosaur injuries seem to suggest ways in which they could have fought more clearly. For example, some kinds of dinosaur tend to have broken ribs in very much the same way as modern bison.
Bisons break ribs when they butt each others' flanks during fights.