Feeding habits of ancient elephant relatives explored in new study
How can we ever know what ancient animals ate? For the first time, the changing diets of elephants in the last two million years in China have been reconstructed, using a technique based on analysis of the surface textures of their teeth.
In a collaboration with Leicester and the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, where the fossilised teeth are curated, Zhang Hanwen a PhD student at the University of Bristol, sampled 27 teeth for tiny wear patterns called microwear.
“We are talking huge, brick-sized molars here – the largest of any animal,” said Hanwen, “but the signs of tooth wear are tiny, down to thousandths of a millimetre. However, these microscopic surface textures can tell us whether they were eating grass or leaves.”
Hanwen took peels of the fossilised teeth in China, using high-grade dental moulding materials, and captured the 3D surface textures under a digital microscope at Leicester. The textures were quantified and analysed to identify what the elephants were eating in the days and weeks before they died.
By comparing the results with information from modern ruminants (deer, antelopes and oxen) of known diet, the study concluded two extinct elephants from Southern China – Sinomastodon and Stegodon – were primarily browsing on leaves. The third, Elephas, which includes the modern Asian elephants, shows much more catholic feeding habit, incorporating both grazing and browsing.
“This method for identifying diet relies on high-quality 3D surface data and analysis,” said Professor Mark Purnell, from our Department of Geology, another co-supervisor of Hanwen’s.
“Very few places have the capability to carry out this kind of analysis of teeth, but it can give more reliable results than other methods because it removes the subjectivity of trying to quantify microwear textures by identifying and counting scratches and pits in 2D microscopic images.”