Why is this trackway site so interesting?
1. At around 7 million years old, this site provides the oldest evidence we have for an ‘elephant’ herd. We know from indirect evidence from body fossils that proboscideans (the order to which elephants belong) probably engaged in sociable behavior tens of millions of years ago. However, direct evidence of social behavior is extremely rare to come by. That’s why the site of Mleisa 1—with its remarkable preservation of the trackways of a single herd as it traversed the ancient landscape—is so interesting.
2. This fossil trackway site is possibly the largest in the world, covering an area of five hectares (that’s the area of 9 American football fields, 7 soccer fields, or the base of the Great Pyramid of Giza). The 260-meter long solitary trackway may well be the longest continuous fossil trackway ever discovered.
3. The Mleisa 1 trackway site is also an amazingly lucky snapshot into the behavior of long-extinct animal, an aspect of biology that is not possible to see from fossil bones and teeth so directly and in the same way. Standing on the site today, one can almost imagine that the animals walked through there yesterday, though in fact these prints were made around 7 million years ago.
4. Mleisa 1 is additionally important because it preserves trails of a herd of 13 proboscideans, but also the trail of a large male individual traveling in a totally different direction. Considering the chances, we were very lucky to have both these trackway types preserved (and crossing) in the only area that survived burial and erosion for us to study it 7 million years later.
How did we study this trackway?
1. Mleisa 1 fossil trackway site covers a very wide extent (ca. 260 m), but the individual foot prints that make up the site are each relatively small (~ 40cm); the prints do not show up in satellite imagery. Accurately mapping the distribution of small features over a large space presents some significant challenges to field data collection.
2. Using a small handheld 10 megapixel Canon S90 pocket camera lifted by a kite, we captured a collection of overlapping images that together completely cover the Mleisa 1 trackway. We stitched these images together to generate a single large composite image that shows the whole trackway, but utilized methods that would allow us to model the track surface in detail. By calibrating the model with ground measurements captured in the field, and checking for accuracy, stride lengths from one foot print to another, we were able to obtain highly accurate and precise measurements.
3. Most importantly, our low-altitude photomosaic (here) gave us a completely new perspective on this site. This is the first time that this combination of methods was used to study any fossil trackway site. This process was instrumental in giving us a broad perspective of the extent and overall character of Mleisa 1.
What are the most important conclusions of our study?
1. Together, the tracks at Mleisa 1 indicate that early elephants 7 million years ago also differentiated into solitary and herding groups, much as elephants do today. And just like living elephants, it seems the males were also the ones to leave the herd and lead solitary lives.
2. The extremely rare find of trackways of a herd traveling together means we can also see that the herd was made up of individuals of different sizes and ages, including even a single calf. To be able to see a social unit so clearly is really a rare occurrence in the fossil record.
3. Finally — and perhaps the most obvious conclusion to the average reader — is that this part of Abu Dhabi Emirate, which is today part of the extremely dry Arabian Desert, once had elephant ancestors roaming through it.
Why is the Baynunah fauna interesting?
1. The many fossil sites found in the Baynunah Formation in the Western Region of the Emirate of Abu Dhabi – Al Gharbia – preserve information about animals and environments dating back to the Miocene Epoch, to between 6 and 8 million years ago. These fossils are the only known occurrence of late Miocene vertebrate fossils in the whole sub-continent, and the only ones known in the whole of Arabia between around 15 million years ago and the Pleistocene.
2. A great diversity of animals lived in the area then, including elephants, hippopotamuses, antelopes, giraffes, pigs, monkeys, rodents, small and large carnivores, ostriches, turtles, crocodiles and fish. Although there is evidence that desert conditions existed then as now, these creatures were sustained by a very large river system flowing slowly through the area, along which was flourishing vegetation, including large trees. The animals resemble those known from Africa during the same period, but there are also similarities with Asian and European species of that time.
3. The fossils are extremely important as representing a window on terrestrial life and Arabian environments at the junction of the three major biogeographical zones of the Old World – the Ethiopian (African), the Palaearctic (Europe and north Asia), and the Oriental (south and south-east Asia) – at a time when the Old World terrestrial fauna was beginning to take on its modern character.
What our study DOES NOT say.
1. Our study does not say that these are the oldest trackways ever discovered, nor that these are the oldest elephant trackways ever discovered because they are not (contrary to what many media sources have published). These trackways are, however, the oldest known for a herd of elephants (they may also be the only known for a herd of elephants, but we can’t be sure). They are the oldest trackways that demonstrate the existence of complex social structure in elephants.
2. Our study does not say that these were elephants like the elephants alive today. Quite the opposite; while these were proboscideans (belonging to the same order as elephants) they certainly looked very different than the living ones. We know from fossil remains from sites close to Mleisa that there were at least three kinds of fossil proboscidean species in the area at that time (ca. 7 million years ago). Of these, the one that most likely made the trackways was called Stegotetrabelodon syrticus and had tusks in both its upper and lower jaws (living elephants only have upper tusks).
3. Our study does not say that the herd and the solitary individual interacted in any way. We can be fairly sure that the herd and the solitary individual crossed this landscape within a few hours or a few days of each other, but there is nothing to indicate they did so at the same time (quite the opposite).
Can we visit the site?
1. Mleisa 1 is located in relatively inaccessible desert terrain. The site is protected by fencing and is under the care and management of the Historic Environment Department at the Abu Dhabi Tourism & Culture Authority (ADTCA). Access to the site has in recent years been restricted by large-scale pipeline and highway construction developments in the area, as well as protective fencing for the newly established Houbara Bustard Conservation Area. Consequently, special permission through ADTCA and the Environment Agency of Abu Dhabi (EAD) is required to obtain access.