Mammary glands 3. The number of teeth of each type in an animal's mouth provides an important clue as to its evolutionary heritage. Mammalogists use a convenient shorthand, or dental formula, to summarize and present this information. Below are some diagnostic characteristics of several mammalian orders and an example of a member of that order. Most rely more on their senses of hearing, smell, and touch than on vision.
Some shrews can echolocate.
The part of the brain that houses the sense of smell is especially well developed. Most have very acute senses. Vision and hearing are excellent in many carnivores, and the sense of smell is often remarkable. Most have relatively large brains. Many are excellent runners.