Dugongidae
Also called dugongs ( Dugongidae ) - - The dugongs are a family within the manatees ( Sirenia). Today there is only one type, the dugong ( Dugong dugon ). Another type, Steller's Sea Cow ( Hydrodamalis gigas) was exterminated by man about 250 years ago.
From the second Seekuhfamilie, the manatees or manatees ( Trichechidae ), the dugongs differ in a number of characteristics. Named giving feature is the deeply furrowed, crescent-shaped caudal fin. The skull is elongated and slightly bent downward. Other differences to the manatees are in the flippers who have no nails in the number of teeth and the cervical vertebrae ( seven dugongs, manatees only six).
During the dugong reaches a length of 2.5 to 3.5 meters, Steller's Sea Cow with up to 8 meters in length was significantly greater.
Dugongs are in the Indian and Pacific Oceans common.
There are numerous fossils of ancestors of dugongs, which date back to the geological epoch of the Eocene Period ( about 50 million years ago). Today's distribution area represents only a fraction of the previous area, as they were spread with numerous genera almost worldwide.