January 18, 2013 2:44 pm
Sea cows, also known as manatees, were not always the Florida-dwelling gentle giants of the sea that they are today. In fact, they once walked on land. Their 48-million-year-old ancestor, Pezosiren, ran all over prehistoric Jamaica and resembled a hippo at first glance. But sea cows also share ancestry with elephants, which first appeared in Africa around 66 million years ago. Paleontologists, however, have always drawn a blank on the evolutionary link between the manatee’s African and Jamaican relatives—until now. Researchers digging around in Tunisia found a skill fragment that fill the missing piece of the puzzle. National Geographic continues:
That might not seem like much to go on, yet the intricate, complicated features in this single bone allowed Benoit and coauthors to confirm that it belonged to a sirenian rather than an early elephant or hyrax. The researchers have wisely avoided naming the animal on the basis of such limited material. They simply call the mammal the Chambi sea cow.
The fact that the mammal lived in Africa confirms what zoologists and paleontologists suspected based upon genetics and anatomical traits shared with elephants and other paenungulates.
The bone is about 50 million years old. The researchers guess the animal it once belonged to resembled Pezosiren more than the modern sea cow, though the bone also hints that the Chambi manatee spent a lot of time in the water since the inner ear resembles that of whales.
The fossil, however, may raise more questions than provide answers. Like, if the Chambi manatee and the Jamaican one are about the same age, when did the dispersal event occur that first separated those animals? How did legged sea cows first make their way across the Atlantic? In the absence of other bones, what did the Chambi manatee look like? As NatGeo writes, paleontologists are slowly assembling the outline of how sea cows evolved, bone by bone.
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