Their study was recently published in the journal Ichnos.
Palaeontologist Dr Charles Helm, Research Associate with the African Centre for Coastal Palaeoscience at Nelson Mandela University
Dr Helm, Research Associate with the African Centre for Coastal Palaeoscience at Mandela University, said he was first shown the fossils by biologist and ecologist Mark Dixon who lives near Sedgefield on the Garden Route.
“We found traces of several large spider burrow systems – one metre wide and as much as 2.7 metres high – at four separate sites in the fossilised sand dunes along this coast.”
Going back 130,000 years when the spiders roamed this area, it was a savanna grassland with extensive wetlands, called the Palaeo-Agulhas Plain, which is now mostly under the sea.
It was home to large herds of mammals, including several extinct forms, such as the long-horned buffalo, giant Cape zebra, and giant hartebeest, elephants and large predators like lion and hyaena. Now scientists have the evidence that it was also home to small predators, namely spiders.
“Because the fossilised spider burrows are the first of their kind in the world, we had the privilege of naming them Lockleyensis gerickensis, after our mentor, Welsh palaeontologist Professor Martin Lockley, who was the director of the Dinosaur Tracks Museum at the University of Colorado at Denver. He initiated the study of Pleistocene invertebrate traces on the Cape south coast, and passed away in 2023,” says Dr Helm.
Mark Dixon inspecting traces of one of the prehistoric spider burrow systems on the Garden Route that would have been one metre wide and 2.7m high. Above is a 10cm scale bar
“When we have a world first, found only on the Cape south coast, it is important for the region and country as it highlights the phenomenal prehistoric record we have here, and it helps to inform us about the evolution of life all the way to the present,” he adds.
The African Centre for Coastal Palaeoscience plays an integral role in this, unravelling the secrets of the Cape south coast with a multidisciplinary international team and attracting top scientists from all over the world.
“We have found numerous trace fossil records from the Pleistocene epoch dating back 130,000 years, and ranging from giraffe footprints to the tracks of turtle hatchlings, but these multiple spider burrows are the first example of this kind of trace fossil in the world,” says Dr Helm, who has led extensive research on vertebrate fossil tracks, traces and burrows along this coastline, documenting almost 400 sites.
By a process of elimination, the scientists excluded wasps, bees, ants, termites or crustaceans, and realised that “these had to be spider burrows, and the spider would have been the size of a species of baboon spider which still lives in this area,” says Dixon, who is familiar with the baboon spider.
Once they knew what they were looking for, they found several more sites with identical burrow systems along the coast.
“We tend to have a bias towards large vertebrate tracks, like those made by elephants and lions, but the smaller, invertebrate traces are just as important, and often more important, in our understanding of these ancient environments”,” says Dr Helm. They concluded that these spiders would probably have preyed on insects like moths, cockroaches and crickets.
The lead author of the research paper is world-renowned ichnologist and sedimentologist, Emeritus Professor Guy Plint from the University of Western Ontario, who specialises in the study of trace fossils and sediments. He came out to the Cape south coast to see what Helm and Dixon had found.
“When we showed Prof Plint the sites, he was intrigued and our team agreed that they were traces of spider burrows. It was the first time he’d been in the area and said the density of prehistoric fossil tracks and traces along this coastline was ‘mind-blowing’.”
Dixon said, “We’ll keep walking these beaches because when the dune cliffs collapse they keep exposing a wealth of unique fossil finds, including early human footprints as humans roamed this landscape from at least 164 000 years ago.
However, when there are big seas, some of these incredible windows into the past also wash away, which is why it is so important to make the most of what is often but a brief opportunity to find and document this phenomenal record of the past that helps us and other scientists interpret the ancient environment.”