The jaw structure and mechanics of insectivores have been little studied. An effort is made here to compare and contrast jaw characteristics of insectivorous bats with those of herbivores and carnivores. Further, in one particular family of bats (Molossidae) jaw modifications are such that animals that take hard-shelled insect prey can be distinguished from those that take soft-shelled insect prey. Beetle-eaters generally have thick jaws, well-developed cranial crests, and fewer but bigger teeth, whereas moth-eaters have thin jaws, little crest build-up, and more but smaller teeth.