How Long Have Manatees Been Around?
Manatees Are An Ancient Species
It's theorized this creature made such a dramatic shift because of increased competition for food and space.
The animal adapted well to its new marine environment, remained an air-breathing creature and became so specialized it could never return to land.
Today, the manatee uses a broad, beaver-like tail to propel it through the water. The front legs, no longer of much practical use, have transformed into a pair of flippers.
A fossil of the world's most primitive sirenian (Prorastomus sirenoides) was discovered in Jamaica. It is a 50-million-year-old, 4-legged, pig-sized mammal which is one of the best examples uncovered so far showing the intermediate stage of the transition from a land to an aquatic animal.
Paleontologist Daryl Domning of Howard University reported this is the first whole skeleton found where the legs could support the animal out of water. The fossil is of an animal almost 7 feet long that may have weighed several hundred pounds.