Beavers clear large amounts of vegetation in aquatic habitats associated with streams and lakes, feeding on small twigs and the inner bark of trees such as poplar, maple, willow and alder. These herbivores leave ample evidence of their presence in the form of toothmarks on downed logs and branches and on tree stumps, chiseled out by their huge, orange-colored front teeth. FiW76-2, Virginia Tech. River otter, 4. By Mary Kay Clark, Curator of Mammals, North Carolina State Museum of Natural Science Article excerpted with permission from the November 1997 issue of Wildlife in North Carolina, a publication of the North Carolina Wildlife Resourecs Commission.
Biologists learn much about health, age and relationships of mammals by studying their skulls.
To begin with, the size and shape of the skull are important. But of all identifying features, the teeth have the most to say about a mammal and its lifestyle. Their number is important, but so are their shape and their location in the jaws. Certain types of teeth may be absent in one species, but present in another. All are important indicators of the animal's eating habits and are crucial for identifying the species.