Washington, April 15 : A new study has suggested that an ancient ancestor of the elephant lived in an aquatic environment 37 million years ago.
According to a report in National Geographic News, chemical signatures from fossil teeth reveal that at least one species of proboscidean, an ancient elephant relative, lived in water.
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, according to Alexander Liu of Oxford University's department of earth sciences.
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.
Carbon isotopes in tooth enamel retained signatures of Moeritherium's diet, while oxygen isotopes evidenced the local water sources from which they originated.
By comparing variations in the ratios of these isotopes with those of terrestrial animals that lived during the same period, the team determined that the proboscidean was likely semi-aquatic.
"Essentially it's a hippo-like mode of life. That's the closest animal that we can think of today," he said.
Moeritherium didn't much resemble modern elephants as it was probably about the size of a tapir-29 to 42 inches (74 to 107 centimeters) tall at the shoulder.
Also, it seems to have lacked a trunk, but may have had a prehensile upper lip.
According to William Sanders of the University of Michigan's Museum of Paleontology, he found the new study to be "first rate," providing convincing evidence that Moeritherium was indeed semi-aquatic.
"Paleontologists have thought for nearly a century that moeritheres were at least semi-aquatic, hippo- or sea cow-like in their overall adaptations and lifeways," he said.
Yet, Sanders cautioned against assuming an aquatic ancestry for modern elephants or even suggesting that all early proboscideans were aquatic.
"Moeritherium is a very specialized animal that may have been off the main line of evolution from that which led to elephants," he said.
The creatures also lived long before the first modern elephants appeared about seven million years ago. Thus, Sanders noted that if elephants did have an aquatic past, some 20 million years of terrestrial evolution would have left few traces today.