A sloping aeolianite surface in the Goukamma Nature Reserve, showing elephant tracks and two elongated grooves interpreted as possible trunk-drag impressions, courtesy of Dr. Charles Helm and with permission from Cambridge University Press.

He didn’t expect to find it.  He was much more focused on one of the beautiful elephant footprints on that stretch of rock.  When he first noticed the long, linear mark near the track, he pondered it, noted it in his mind, and expected to review it on his next visit.

That was in 2015.  He didn’t have a chance to review that same rock until it appeared again in 2019, thanks to the shifting of sand and the lack of a high tide that had otherwise covered it for years.

Which is when he and his colleagues noticed even more elephant tracks and yet another long mark on the opposite side of them.  One mark near one set of tracks was difficult to interpret. But two marks situated on either side of an elephant trackway pointed to an exciting possibility: a trunk-drag mark.  

Today’s elephants are known to drag their trunks for a variety of reasons, among them bulls in musth.  They leave curving marks alongside their footprints—marks that almost look like a broken ‘s’—on the left and then the right, as they walk along.  

Could these two marks left in the rock be traces of ancient elephant trunks?

Photogrammetry colour mesh of a purported elephant trunk-drag impression; vertical and horizontal scales are in metres. Mark on the left is one of the trunk-drag traces and the round mark on the right is an elephant footprint. Courtesy of Dr. Charles Helm and with permission from Cambridge University Press.

You need to plan at least a day to visit the Goukamma Nature Reserve in South Africa. This is what Dr. Charles Helm, lead author and research associate at the African Centre for Coastal Palaeoscience in Nelson Mandela University, tells me in a video interview.  That, he explains, allows for the long walk to the coastline, time to explore, and then time for the long walk back.  It’s a trip many ichnologists, proboscidean researchers and paleontologists would willingly make in a heartbeat, for along 10 kilometers of coast, roughly 4-5 of those kilometers are filled with fossil tracks.  And it is where Charles and his team discovered these uniquely proboscidean trace fossils described in a recent paper.

Among other ancient traces, the Cape south coast of South Africa is home to over 300 track sites, 35 of which are proboscidean.  Humans walk these sands today, but this was, according to the profuse amount of tracks in multiple layers of rock, a well-traversed spot for ancient elephants during the Pleistocene.  At that time, the amount of coast would have been considerably larger, comprising what is known as the Palaeo-Agulhas Plain.  The Palaeo-Agulhas is underwater now, but at times during the Pleistocene, it was open sand.

Dr. Hayley Cawthra, co-author, chief scientist at the Council for Geoscience (CGS) and a research associate at the Nelson Mandela University, explained in an email how the rocks in this particular part of the world formed “from beaches and dunes by a natural cement-making process, whereby shell material is dissolved to form calcium carbonate that binds grains of sand into rocks.”

In other words, ancient sand dunes (known as “aeolianites”) and beaches (“cemented foreshore deposits”) became cemented over time, preserving the traces that ancient life left upon them.  

The Goukamma Nature Reserve is only one of the proboscidean sites highlighted in the recent paper, but it is particularly important for the number of tracks it contains as well as being the location of the trunk-drag traces. Charles describes it as “one of the areas with the densest concentration of tracks that we have.” But it’s also subject to strong natural forces that constantly change whether those tracks can be seen or not.  Storms, high tides, cliff collapses and shifting sands constantly transform the landscape.

“You never quite know what you’re going to find!” Charles said. “It’s not like: ‘oh well, I know that coastline because I’ve been there before.’  No. Every time you go it’s going to be different.”

Fossil footprints can be seen as we might expect to see them: large round tracks on rock surfaces.  They can also, however, be seen in cross-section.  Which means that rather than the easily-identifiable round tracks, they take on different shapes altogether.  Even further, the sand below the tracks is impacted in very predictable ways, indicating that something of great weight walked that earth. 

“Say you have an elephant walking on a dune today,” Charles expressed. “You’re going to think, ‘well, that’s cool. I can follow its tracks in the sand.’  You’re not going to realize that there’s a record underneath that surface going down as much as maybe a meter in all the previous layers that are there.  That record is preserved there.  It’s all there; it’s just a ‘secret’.”

That record is something ichnologists (the term for those who study trace fossils) have learned to interpret and identify in fossil tracks. Thus, in one large section of exposed cliff, for example, you can see elephant trackways in various layers of that rock, indicating that over different time periods, elephants kept walking that same sandy route.  Whether it was days, weeks, months or years has yet to be determined. But, as Charles explained, the elephants “weren’t just passing through once; they were repeatedly using the area. Whether that means proximity to water or just a good corridor of travel, we don’t know.”

An elephant track seen in section, illustrating deformation of underlying layers. Courtesy of Dr. Charles Helm and with permission from Cambridge University Press.

Eroded elephant tracks and infill layers may take on remarkable forms (indicated by white arrows); courtesy of Dr. Charles Helm and with permission from Cambridge University Press.

Elephant body fossils, on the other hand, are scarce.  Because the deposits in which the tracks are found are between approximately 400,000 – 80,000 years old, and because no earlier type of elephant is known to have existed in that area after 400,000 years ago, the authors suggest that the elephants who walked these ancient dunes were a type we know today: the African savanna elephant (Loxodonta africana).

I asked Mpilo Nxumalo, Msc Candidate at the Evolutionary Studies Institute, University of Witwatersrand, for his thoughts on this research, and he wrote in an email, “It is amazing really. As paleontologists, we rely on body remains to decode the past and the evolutionary history of things. My research is about the evolution of the trunk, which is soft tissue material and does not preserve. In the absence of bones and soft tissue material, how can we know if something possessed a trunk or not? We can use these drag marks in the fossil record (traces), and make analogies with drag impressions from living elephants (compare them). This will help us gain real insight, and help us fill in the gaps in the fossil record where anatomical remains are not available.”

Along with trackways, the authors have discovered possible ancient elephant coprolites and possible elephant rubbing marks.  It’s an exciting area whose ichnofossils have only been formally described as of 2008.  In other words, there is a lot yet to be discovered.

“We’ve got this little carnivore—a mongoose or something—with a latrine, and we can see layer after layer of these coprolites,” Charles described. “But we’ve also got these elephant tracks going through there, so we’re thinking, ‘oh this poor little mongoose.’”

“I’m hoping that what we’re doing,” he continued, referencing the research into many trace fossil sites in the Cape south coast, “is the foundation for a long-term ichnology project.”

One of the authors measuring an underwater elephant track on the Robberg Peninsula; courtesy of Dr. Charles Helm and with permission from Cambridge University Press. Charles said of this picture that these underwater tracks “were in an area with numerous elephant tracks, and the surface was at the bottom of a rock pool, and there in front of our eyes was an underwater trackway. It was a hot African day, and therefore was no problem for one of us to go for a dip and take measurements. The Pleistocene was a time of major sea-level fluctuations, and there are likely many sub-marine surfaces off the coast with further tracks, which we have not explored for yet.”

Enormous thanks to Dr. Charles Helm, Dr. Hayley Cawthra, Mpilo Nxumalo and Lizette Moolman for taking time during their very busy lives to discuss this exciting research with me! Thank you as well to Dr. Derek Booth for his help obtaining permission to use pictures from the paper at Cambridge. This is part one of two posts. Stay tuned!

References:

  1. Helm CW, Lockley MG, Moolman L, Cawthra HC, De Vynck JC, Dixon MG, Stear W, Thesen GHH (2021). Morphology of Pleistocene elephant tracks on South Africa’s Cape south coast and probable elephant trunk-drag impressions. Quaternary Research 1–15. https://doi.org/10.1017/qua.2021.32