February 22, 2012
Ancient Footprints Give Evidence Of Prehistoric Elephant Social Structure
An international team of researchers has found the oldest known evidence of how elephant ancestors interacted socially.
Researchers from Germany, France, the U.S. and the United Arab Emirates (UAE) analyzed seven-million-year-old footprints discovered at the Mleisa 1 site in UAEThe site features long trackways of a single herd of at least 13 elephant individuals that walked through mud and left footprints that hardened.
They analyzed the trackway stride lengths to reveal that the herd contained a diversity of sizes, from adults to a young calf.
This discovery is the earliest direct evidence of a social structure existing in prehistoric elephants.
“This is an absolutely unique site, a really rare opportunity in the fossil record that lets you see animal behavior in a way you couldn´t otherwise do with bones or teeth," Faysal Bibi, primary author from the Institut International de PalÃ©oprimatologie, PalÃ©ontologie Humaine : Ãvolution et PalÃ©oenvironnements in Poitiers, France, and the Museum fÃ¼r Naturkunde in Berlin, Germany, said in a press release.
They also found an 853 foot trackway of a solitary male at the same site, indicating that the group differentiated into solitary and social groups.
Adult females in a group of elephants today would lead the herds, while males disperse at sexual maturity and come back only to mate.
Mleisa 1 is one of the largest trackway sites in the world, and covers an area of nearly 540,000 square feet.
The site has been known for a long time, but the story of it became much clearer once it was observed from the air.
The team outfitted a kite with a special camera to take hundreds of aerial photos, which were digitally stitched together to form a photomosaic of the site.
“Once we saw it aerially, it became a much different and clearer story,” co-author Brian Kraatz, assistant professor of anatomy at Western University of Health Sciences, said in a press release. “Seeing the whole site in one shot meant we could finally understand what was happening.”
The ancient freshwater ecosystem in the area helped support a thriving diversity of African-like fauna during the time.
Once the river dried up, those animals disappeared with the river system, including the elephant ancestors that left the footprints.
"The trackways are visually stunning." co-author Andrew Hill, professor of anthropology at Yale University, said in a press release. "It is quite obvious to anyone, without any technical knowledge, that these are the footprints of very large animals, and to learn that they are over 6 million years old presents a visitor with the sensation of walking back in time, across a Miocene landscape where elephants might have strolled by just a little time before."
The paper is published in the current issue of Biology Letters.
On the Net: