London - Scientists may have solved an evolutionary riddle of how the ancestors of elephants changed their diet from soft leaves to tough grasses and, in the process, became one of the dominant herbivores of the savannah.
Professor Adrian Lister, of the Natural History Museum, said a study of the fossils of animals with tusks and trunks, such as elephants and mammoths, has revealed that the crucial change in diet occurred about 3 million years before elephants developed the high-crowned teeth needed for chewing grasses.
The study, published in the journal Nature, found that about 8 million years ago various species changed their diet and feeding behaviour by switching from a diet based on leaves from trees to one on grazing for grass.
Professor Lister said that the change of lifestyle was relatively rapid and occurred at a time when there were still plenty of forests, indicating that it was a behavioural “choice” rather than a necessity.
Yet it took another 3 million years for the elephants to evolve high-crowned teeth.
“This long delay between the behavioural change and the evolutionary response suggests that it takes time for complex changes in teeth and skulls to adapt to lifestyles. After that, the dental changes show a clear example of progressive evolution for another 4 million years,” Professor Lister said. - The Independent