Manatees did not evolve from elephants, although these two types of mammals did both descend from a group of common ancestors known as Tethytheria. These early hoofed mammals lived during the early Cenozoic age and were small, rodent-like creatures that lived on land. Over time, some of these creatures evolved into the land-dwelling elephants we know today, while others evolved into sea-dwelling manatees.
Sirenians, the ancestors of manatees, first emerged sometime during the Eocene Epoch of the Cenozoic Era, some 55 million years ago. These sea-dwelling creatures lived in the Tethys Sea, located between Africa and Eurasia, according to the Natural History Collections of the University of Edinburgh website. Around the same time the Sirenians emerged, the land-dwelling Proboscideans developed from the Tethytheria as well. Manatees belong to the order called Sirenia, and are direct descendants from the Sirenians. Elephants, on the other hand, are direct descendants of the Proboscideans, making these two groups closely, but not directly, related.
Descended from the ancient Sirenians, early manatees themselves didn't appear until around 15 million years ago during the Miocene Epoch. It was during the same period that early elephants first developed from the Proboscideans, according to "Horns, Tusks, and Flippers: The Evolution of Hoofed Mammals." While neither of these two types of mammals descended from the other, they do share similar DNA based on their evolutionary relationship. In fact, many seemingly unrelated species share a genetic relationship, even if they aren't in the same family, genus or species. Modern species of manatees, elephants, hyraxes and aardvarks are all closely related and considered "subungulates," according to the Annenberg Lerner website. Subungulates all descend from early hoofed animals called ungulates, but not directly from each other.
As much as they may resemble each other, manatees don't share any evolutionary relationship with other marine mammals. Most marine mammals, such as dolphins, whales and porpoises, are members of the order Cetacea and descended from a group of animals also known as Cetacea. This means the closest relatives of the manatee are actually land-dwelling creatures like elephants and hyraxes, rather than other marine mammals. Like elephants and hyraxes, the manatee is an herbivore -- in fact, manatees are the only marine mammal herbivore species in existence, according to Sirenian International.
There are only three species of manatees remaining today: West Indian, West African and Amazonian. There are two sub-species of the West Indian species, which are the Florida and Caribbean, according to the Dolphin Research Center. Like their land-dwelling relatives the elephants, these gentle giants have thick skin covered with bristles, nails on their forelimbs and replaceable teeth; manatees even have a trunk-like flexible upper lip. Unfortunately, these large creatures, averaging in size from 800 to 1,200 pounds, are endangered due to habitat loss, hunting and collisions with watercraft, according to the Save the Manatee Club. Endangerment is a situation they share with elephants. The International Union for Conservation of Nature lists Asian elephants as endangered and African elephants as a threatened species, according to Seaworld.org.
- Annenberg Lerner: Evolution -- Manatee Relatives
- Dolphin Research Center: Manatee Fact Sheet
- Natural History Collections of the University of Edinburgh: Order Sirenia: The Dugong and the Manatees
- Save the Manatee Club: Manatee Facts
- Earth System History; Steven M. Stanley
- SeaWorld.org: Elephants
- Sirenian International: Manatee Facts and Information
- Horns, Tusks, and Flippers: The Evolution of Hoofed Mammals; Donald R. Prothero and Robert M. Schoch
- Sirenian International: Frequently Asked Questions
- University of California Museum of Paleontology: The Proboscidea
- Jupiterimages/Photos.com/Getty Images