The seven-million-year-old footprints, found in the Arabian Desert, provide the oldest known evidence of how elephant ancestors interacted socially. The tracks reveal that the herd walked through mud and left footprints that hardened, were buried, and then re-exposed by erosion. Analysis of trackway stride lengths reveals the herd contained a diversity of sizes, from adults to a young calf, making this the earliest direct evidence of social structure in prehistoric elephants ever discovered.
An international team from Germany, France, the United States and the United Arab Emirates made the discovery at the Mleisa 1 fossil site, part of the Baynunah Formation, a sequence of mostly river deposited sands that is widely exposed over the Al Gharbia region of Abu Dhabi Emirate.
“Basically, this is fossilized behaviour,” says co-author Faysal Bibi. “This is an absolutely unique site, a really rare opportunity in the fossil record that lets you see animal behaviour in a way you couldn’t otherwise do with bones or teeth.”
Mleisa 1 is one of the largest trackway sites in the world, covering an area of 5 hectares. Though the site had been known for some time, it was only when the scientists photographed it from the air that its significance became clear.
According to co-author Brian Kraatz, “Once we saw it aerially, it became a much different and clearer story. Seeing the whole site in one shot meant we could finally understand what was happening.” The researchers used a camera-mounted kite to take hundreds of aerial photos that were then digitally stitched together to form a highly accurate photomosaic of the site.
"The trackways are visually stunning.” says co-author Andrew Hill. “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 Ma 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."