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Class Mammalia
Mammal
teeth: 
The teeth
of mammals are highly specialized for their specific diet.
Mammals are heterodont,
meaning that they have several types of teeth.
Mammal
teeth are thecodont, being set in sockets in the
jaw bones.
Most
mammals are diphyodont,
having two sets of teeth. They first grow a set of
deciduous teeth, which are shed and replaced by
permanent teeth as the jaws grow to full size. These "milk
teeth" do not include molars. The permanent teeth of many
mammals stop growing when they reach full size. These
teeth are called rooted teeth. The teeth in some
mammals continue to grow throughout life. The incisors
of rodents are examples of these rootless teeth.
Dental
Formulas:
Mammals
can be identified by their dental formula, which
is an expression of the number of each type of tooth on
one side of the upper jaw over the number of each type
of tooth on one side of the lower jaw.
| 3/3 |
0/1 |
3/3 |
2/3 |
| incisors |
canines |
premolars |
molars |
The example
above represents a mammal whose dental formula is 3/3,
0/1, 3/3, 2/3. Each side of the upper jaw would have
3 incisors, 0 canines, 3 premolars, and 2 molars. Each
side of the lower jaw would have 3 incisors, 1 canine,
3 premolars, and 3 molars. This mammal would have a
total of 36 teeth.
Some
Dental Formulas
| Humans |
2/2, 1/1, 2/2, 3/3 |
| Dogs |
3/3, 1/1, 4/4, 2/3 |
| Cats |
3/3, 1/1, 3/2, 1/1 |
| Raccoons |
3/3, 1/1, 4/4, 2/2 |
| Opossum |
5/4, 1/1, 3/3, 4/4 |
| Skunk |
3/3, 1/1, 3/3, 1/2 |
| Shrews |
3/1, 1/1, 3/1, 3/3 |
| Rabbits |
2/1, 0/0, 3/2, 3/3 |
| Rodents |
1/1, 0/0, 3/2, 3/3 |
| Squirrels |
1/1, 0/0, 2/1, 3/3 |
| Horses |
3/3, 0/0, 3/3, 3/3 |
| Pigs |
3/3, 1/1, 4/4, 3/3 |
| Cows & Sheep |
0/3, 0/1, 3/3, 3/3 |
| Deer |
0/3, 0/1, 3/3, 3/3 |
| Armadillos |
7/7 |
The external
appearance of a mammal is greatly affected by several environmental
factors. Because of this, characteristics of the skull,
teeth, and feet are generally used in classification and
identification of mammals instead of color, size, etc.
The skulls of mammals are quite distinct and can be used
to identify the species of the animal. The drawings below
shows the top and bottom of a mammal skull with parts
labeled.
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Incisors -
teeth with a single cutting edge.
