dugong: 300 kg
Dugong: 2.6 m
Dugong: 12 months
Steller's sea cow, Hydrodamalinae, Tethytheria
The Dugongidae are a family in the order of Sirenia. The family has one surviving species, the dugong (Dugong dugon), one recently extinct species, Steller's sea cow (Hydrodamalis gigas), and a number of extinct genera known from fossil records.
The genera Eosiren, Eotheroides, and Prototherium have been assigned to Halitheriinae in the past, but recent cladistic analysis recovers these genera as basal to the clade formed by Trichechidae and Dugongidae. Moreover, Halitheriinae is paraphyletic with respect to Dugonginae and Hydrodamalinae, and further use of the name should be discontinued because the type genus is based on a non-diagnostic tooth.