Was early elephant an amphibian?

April 21st, 2008 - 5:24 pm ICT by admin  

Washington, April 21 (IANS) Scientists studying two very ancient elephants surmised that they were probably semi-aquatic mammals, eating freshwater plants. “Molecular data from modern elephants share a common ancestry with the sirenians - aquatic sea cows and dugongs,” said Alexander Liu of Oxford University, co-author of the report.

“Elephants may have an ancestor which was amphibious in its mode of life and we wanted to know if Moeritherium or Barytherium (existing 37 million years ago) was this semi-aquatic ancient relative.”

“Unfortunately only fragments of the skeletons of these early elephants survive, so instead of looking at their bones we looked at the chemical composition of their teeth to determine what they ate and how they lived,” he added.

Alex Liu, with colleagues Erik Seiffert from Stony Brook University (US) and Elwyn Simons from the Duke Lemur Center (US), analysed the oxygen and carbon isotope ratios within tooth enamel from both extinct species.

While carbon isotopes can give clues as to an animal’s diet, oxygen isotopes found in teeth come from local water sources - and variations in the ratios of these isotopes can indicate the type of environment the animal lived in.

They compared the ratios of these isotopes to terrestrial animals from the same period and these results - when combined with results from studies of embryology, molecular data, and sedimentology - lead them to believe that Moeritherium was semi-aquatic.

Liu said: “We now have substantial evidence to suggest that modern elephants do have ancient relatives which lived primarily in water.”

These findings were published online in PNAS.

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