Sea cows take to the water
Relatives of elephants become aquatic grazers, and one of the earliest still has four working legs.
- When
- —
- Duration
- 2 million years
- Known to
- ± 1 million years
- Era
- Eocene, Cenozoic
Sirenians — manatees and dugongs — descend from afrotherian stock close to elephants and enter the water independently of whales, at almost the same time. Pezosiren from Jamaica, around 50 million years ago, is a fully quadrupedal walking sea cow with the dense ribs and retracted nostrils of an aquatic animal but legs that still work on land. Unlike whales, sirenians stay in shallow coastal water and become grazers on seagrass, a niche they still hold.