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The dugong (/ ˈ d (j) uː ɡ ɒ ŋ /; Dugong dugon) is a marine mammal.It is one of four living species of the order Sirenia, which also includes three species of manatees.It is the only living representative of the once-diverse family Dugongidae; its closest modern relative, Steller's sea cow (Hydrodamalis gigas), was hunted to extinction in the 18th century.
Unlike those of manatees, the dugong's teeth do not continually grow back via horizontal tooth replacement. [38] The dugong has two tusks which emerge in males during puberty, and sometime later in life for females after reaching the base of the premaxilla. [33] The number of growth layer groups in a tusk indicates the age of a dugong. [39]
Dugong skeleton displayed at Philippine National Museum. Dugongidae's body weight ranges from 217 to 307 kg for juveniles, 334 to 424 kg for subadults, and 435 to 568.5 kg for adults. Oral temperatures for individual dugongs is determined from 24° to 34.2 °C. Heart rate readings are from 40 to 96 bpm and vary between individual dugongs.
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. Subcategories
A fossil reveals how a now-extinct species of dugong was swimming in the sea about 15 million years ago when it was preyed upon by a crocodile and a tiger shark.
A diagram of generalized tribosphenic molars with notable features labelled. Upper left molar in pink, lower left molar in blue. Mesial (forwards) is to the left. Teeth are depicted in left lateral view (left side and center of the image) or occlusal view (right side of the image).
Marine mammals have evolved a wide variety of features for feeding, which are mainly seen in their dentition. For example, the cheek teeth of pinnipeds and odontocetes are specifically adapted to capture fish and squid. In contrast, baleen whales have evolved baleen plates to filter feed plankton and small fish from the water. [32]
Paenungulata (from Latin paene "almost" + ungulātus "having hoofs") is a clade of "sub-ungulates", which groups three extant mammal orders: Proboscidea (including elephants), Sirenia (sea cows, including dugongs and manatees), and Hyracoidea . At least two more possible orders are known only as fossils, namely Embrithopoda and Desmostylia. [a]