Teeth continue to resist destruction after the death of the individual that made them. Commonly, teeth will survive scavenging and stream transport that totally destroys other skeletal elements. By comparing the teeth of extinct fossil species with the teeth of living species, we can deduce the types of foods that the extinct species ate. In turn, we may determine that species' position in the food web of the ancient community in which it lived. We can even reconstruct an ancient community when nothing but fossil teeth are preserved in a geologic deposit.
Teeth display variable shapes for different functions.
There are just a few basic types of tooth shapes, although many variations on those basic types exist. Mammals, such as dogs and humans, commonly display four basic tooth shapes in one jaw. The four basic types of mammal teeth are incisors, canines, premolars and molars. They are used by most mammals to nip food, although rodents have long, ever-growing incisors, designed for gnawing. Some herbivores, such as deer and cattle, have lost the upper incisors.