for National Geographic News
The family tree of the largest living land animal may have its roots deep in the water, a new study suggests.
Chemical signatures from fossil teeth reveal that at least one species of proboscidean, an ancient elephant relative, lived in an aquatic environment.
The teeth of the ancient animal, which belonged to a genus called Moeritherium, suggest that it ate freshwater plants and dwelled in swamps or river systems, said Alexander Liu of Oxford University's department of earth sciences.
"Essentially it's a hippo-like mode of life. That's the closest animal that we can think of today," said Liu, lead author of recent research on the teeth.
Moeritherium lived some 37 million years ago, many millions of years after the genetic lineages of elephants and sirenians split, Liu said.
Teeth Solve Mystery
Moeritherium didn't much resemble modern elephants. It was probably about the size of a tapir—29 to 42 inches (74 to 107 centimeters) tall at the shoulder.
It seems to have lacked a trunk but may have had a prehensile upper lip.
The animal's teeth were unearthed in northern Egypt's Faiyum region, which in ancient times was a shallow estuary or coastal system where the environment changed often.
The Moeritherium fossils were found in rock containing strong evidence of swamp and river ecosystems. But it was difficult for scientists to tell whether the ancient animals had actually lived in such an environment or whether their bodies had washed up there after their deaths.
In the end, the teeth told the tale.
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