One of the largest paleontological finds in history has been discovered in the United Arab Emirates. Researchers working in the country's deserts have uncovered a massive tract of land riddled with the footprints of four-tusked titans called Stegotetrabelodon syrticus — the earliest known members of the elephant family. It's one of the best windows we've got on ancient animals' social behavior.
The footprints are between 6 and 8-million-years-old, making them the oldest elephant tracks on record. Individually, the impressive imprints measure about 40 centimeters across; taken together, however, they cover an area the size of seven football fields.
By some estimates, the prints comprise the largest fossil trackway ever discovered, which is surprising, due to the fact that few people were even aware of their existence until 2001. That's when locals from the area — who knew of the tracks, but had long believed them to belong to either dinosaurs or mythical giants — first showed them to scientists. In fact, it wasn't until early last year, when researchers first mapped the fossil field from the air, that anyone recognized the true scope of the discovery.
It was then, recalled vertebrate paleontologist Faysal Bibi "that we realized what we had and how we could go about studying it." In a release, Bibi explained that paleontologists study the social lives of ancient elephants by reading their footprints.
"Basically, this is fossilized behavior," said Bibi, who is first author on the paper describing his team's findings, published yesterday in Biology Letters. "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."
The cluster of tracks running from top to bottom suggests that these prehistoric behemoths sometimes traveled in herds. The researchers estimate that these impressions were formed by at least 13 individuals of varying size and age, all plodding along in unison. (Fun fact: this picture was taken by strapping a remotely operated camera to a kite).
Look closely, however, and you'll notice a single set of tracks cutting diagonally through those of the herd. Judging from their size, they belonged to a solitary male, who the researchers suspect never actually encountered members of the group. Bibi and his colleagues say that, taken together, the tracks paint a portrait of society similar to what we see in modern day elephants — one characterized by stable, matriarchal family units, and lone, mate-seeking males.
"We know that the two elephant species today show female-led family groups," explained study co-author Brian Kratz, in an interview with Wired's Brian Switek. "This study shows that such behavior extends beyond their last common ancestor, if indeed, the track maker was Stegotetrabelodon." He continues:
The most-interesting part here, in my mind, is not what the is answer to the question about the antiquity of this behavior, it's that the fact we could even date it back this far. This is nothing short of amazing considering the difficulties in inferring any sort of behavior from fossils.
Top image by Mauricio Antón, photo of trackway by study co-author Nathan Craig