From Academic Kids
Sirenia are herbivorous mammals of coastal waters. They have evolved aquatic adaptations: they have arms, which are modified into paddles, but no legs, are fat, and have highly modified skulls with greatly reduced dentition. Their nipples are under their arms (see the picture of a pair of manatees).
- ORDER SIRENIA
The earliest known Sirenian is Pezosiren portelli (http://home.t-online.de/home/rothauscher/dugong/4legs.htm).
Placentalia: Xenarthra | Dermoptera | Desmostylia | Scandentia | Primates | Rodentia | Lagomorpha | Insectivora | Chiroptera | Pholidota | Carnivora | Perissodactyla | Artiodactyla | Cetacea | Afrosoricida | Macroscelidea | Tubulidentata | Hyracoidea | Proboscidea | Sirenia