Pleistocene Elephant Tracks and Traces in National Parks on the Cape South and East Coast
Through the Cape south coast ichnology project, since 2008 more than 300 vertebrate Pleistocene tracksites have been identified along a 350 km stretch of the coastline of South Africa between Arniston and Robberg. A number of these occur within the coastal section of the Garden Route National Park. These are found in aeolianites (the cemented remains of dune surfaces) and cemented beach deposits. The majority are in the 70,000–140,000 year range. Such fossil tracksites can tell us many things about what happened on those ancient dunes and beaches, and what the environment was like then.
In a recently published open-access article in Quaternary Research (https://www.doi.org/10.1017/qua.2021.32) we focused on the 35 elephant tracksites that have thus far been identified and their implications. These sites would have been situated at the margin of the vast Palaeo-Agulhas Plain which was alternately exposed and inundated during Pleistocene sea-level oscillations. This relative profusion of elephant tracksites can be contrasted with a relative absence of documented Pleistocene elephant bones from the region.
Fossil elephant tracks can take a number of forms, from familiar depressions (Figure 1), to natural casts representing the layer that filled in the tracks (Figure 2), to profile views that indicate how underlying layers were also deformed in a predictable fashion by as much as 30 cm (Figure 3). In some cases, elephant tracks on beaches were precursors for the formation of potholes. In some places they have been eroded into bizarre shapes, which beach hikers admire and pass by without knowing their intriguing origins.
Analogies can be drawn between Pleistocene elephant tracks and Mesozoic dinosaur tracks: in both scenarios they were the largest tracks of their time, made by the heaviest creatures. In fact, it appears that the elephant tracks we identified at Robberg, measuring as much as 70 cm, are the largest tracks ever identified since the “Age of Dinosaurs”. Elephant tracks deform underlying layers to such a degree that at times the ‘right-way-up’ of a gigantic fallen block of rock can be determined from a distance just by contemplating the tracks in profile.
Sometimes, when elephant tracks can be discerned in profile in multiple successive layers, conclusions can be drawn about repeated use of an area over time. Our ‘record’ for this phenomenon was a vertical section of 26 metres. Trackmaker associations are also of interest. At one site a track of the extinct long-horned buffalo (Syncerus antiquus), was found within an elephant track, beside a possible rhinoceros track and a track of Equus capensis, the extinct giant Cape horse.
In addition to this cornucopia of tracks and track forms, what appears to be the first example in the global trace fossil record of elephant trunk-drag impressions was recently identified. These were located on an aeolianite surface in the Goukamma Nature Reserve. The site is only exposed at low tide, being subject to intense wave action during high tides and storm surges. It is also usually covered by metres-thick layers of sand, so we were fortunate to find it during a rare occasion during which it was exposed. Here, beside an elephant trackway comprising thirteen tracks, traversing a dune slope, we encountered a ‘serpentine’ sequence of two long, slightly curved groove features with an outward convexity, one on each side of the trackway. Slight displacement rims were present, and we could tell that the tracks were registered after the groove features.
The most plausible interpretation of these features is that they were made by an elephant dragging its trunk, or at least dragging something that it was gripping in its trunk. The extant African bush elephant (Loxodonta africana) is known to indulge in trunk-dragging behaviour under a variety of circumstances, including musth, a cyclical period when male elephants experience a heightened level of testosterone production.
Palaeo-environmental inferences can be made from the frequency with which fossil elephant tracksites are encountered. Elephants are ecosystem engineers, and their presence may result in large-scale effects on the landscape, for example they can transform woody habitats to more open habitats. Firstly, therefore, they may well have facilitated the development and maintenance of the mosaic of woodland and grassland habitats that characterised the Palaeo-Agulhas Plain during the Pleistocene.
A second implication sheds light on the fate of the regional elephant population: the “Knysna elephants” were the most southerly group of elephants in Africa, and the only free-ranging elephants in South Africa. Their numbers were decimated in the 19th century. Evidence indicates that only one elephant remains, an adult female in her forties. She inhabits an area approximately 18 km from the site containing the fossil trunk-drag impressions. The profusion of Pleistocene elephant tracksites buttresses Holocene and historic evidence that elephants made widespread use of open areas in the region, and that the remaining elephants retreated into dense afrotemperate forest for protection in recent centuries, where hunters had difficulty finding them.
While the main focus of attention has been the Cape south coast, including the elephant tracksites in the Garden Route National Park illustrated here (Figures 1, 2. 3), a brief reconnaissance expedition to the coastline at Woody Cape in Algoa Bay led to the discovery of fossil elephant tracks there as well, within the coastal section of the Addo Elephant National Park (Figure 4). It is perhaps remarkable that in a park so famous for its elephant population, the the Pleistocene ancestors of these pachyderms left their tracks, and that these are now amenable to our recognition and interpretation.
Manus-pes sets of elephant tracks in the Garden Route National Park; the distance between the outer circles of the scale bar = 25 cm.
A natural cast of a large elephant track on a loose slab in the Garden Route National Park. The slab flipped over as it fell, now lies ‘upside down’, and the cast of the track represents the layer of sand that filled in the original track; scale bar = 10 cm.
Elephant track seen in profile in the Garden Route National park, showing how underlying layers are deformed.
Two large elephant tracks in the coastal section of the Addo Elephant National Park. The track on the right is 40 cm long; scale bar = 130 cm.
Reference
Helm, C.W., Lockley, M.G., Moolman, L., Cawthra, H.C., De Vynck, J.C., Dixon, M.G., Stear, W., Thesen, G.H.H. Morphology of Pleistocene elephant tracks on South Africa’s Cape south coast, and probable elephant trunk drag impressions. Quaternary Research. https://www.doi.org/10.1017/qua.2021.32
