World-renowned Albany Museum verterbrate paleontologist, Dr Rob Gess, enthralled U3A members at the Settlers Park Don Powis Hall with a presentation on the famous Waterloo Farm lagerstӓtte (exceptional fossil site) outside Makhanda.
“This fossil site provides our only comprehensive window into life in polar regions 365 million years ago. At the time Africa was part of the supercontinent Gondwana (which later broke up into Africa, South America, India Madagascar, Antarctica and Australia.),“ he said.
He said what is now the Eastern Cape was situated within the South polar circle and the rocks that are now beneath our feet, were deposited within a great rift valley.
“Only the northern rim of Gondwana (now represented by Australia), intruded into tropical regions. Most of what is known about the latest Devonian [period] (+/- 375-360) million years ago, is known from rocks now found in North America, Greenland, Europe and Russia, which then formed the northern supercontinent of Laurasia, which was situated almost entirely in the tropics.”
Gess revealed that records from Laurasia indicate that with the exception of flowering plants, during the Devonian, plants had rapidly evolved from simple marsh-loving forms to the ancestors of all major groups today.
In parallel, jawed vertebrates had evolved from primitive armour-plated fish to all the groups found today, in addition to many other groups that would go extinct in a massive extinction event at the end of the Devonian, or in subsequent extinction events.
Towards the end of the Devonian the first remains of tetrapods (four-legged animals) made their appearance in the fossil record. These creatures still lived in the water and had tadpole-like tails, but already had four legs for sprawling in the shallows.
Gess said these prototetrapods of the Devonian were the common ancestors of all later legged vertebrates including amphibians, reptiles, birds, and mammals including human beings.
“Only a few small plant fragments were represented in the fossil record of South Africa and it was assumed that due to its near-polar position, this part of Gondwana was inhospitable to life. It was widely held, therefore, that such important events as the evolution of tetrapods and their subsequent expansion onto land had occurred in the tropics, almost certainly in Laurussia.”
Protests
Gess told his audience that these assumptions were, however, to be completely overturned following events in 1985.
“As a result of protesters [in Makhanda] blocking the road between Port Elizabeth and East London, the government decided to build a bypass around then-Grahamstown on the N2, cutting through the hills to the south. At Waterloo Farm they cut through an unusually thick layer of black shale that would prove to be one of the most important fossil sites of its age in the world.”
The roadworks led to the discovery among the shale – fossilised remains that indicated the existence of lampreys – a blood-sucking parastic eel-like fish that doesn’t have a jaw.
He said at the time these were the oldest lampreys ever found that existed 365 million years ago during the Devonian age.
At Gess’s urging, the South African Roads Agency, Sanral, helped him move over a period from the 90s into the mid-2000s 100-tons of shale which now sits in his back garden in Bathurst. He told his audience this was the world’s best preserved shale site that revealed fossilised remains from this era.
Careful research by Dr Gess, over the last 30 to 40 years has revealed a wealth of palaeontological material. This is the only estuarine fossil site of its age to preserve not just bones, teeth, and decay resistant plant matter, “but extremely rarely preserved soft tissue material, due to periodic burial in oxygen poor conditions”.
“Hence delicate seaweeds, cartilaginous elements and the delicate outlines of skin and fish fins are preserved as silvery white films in the black rock. These fossils are all from about 365 million years ago and essentially represent a single point in time,” said Gess.
Fossils from Waterloo Farm famously include bones from two different species of fossil tetrapod, which are the earliest tetrapod remains from South Africa by 90 million years, “and the only Devonian tetrapod remains known from outside the Devonian tropics”.
Gess pointed out that tetrapods probably had a deep history in southern Gondwana.
“We literally have an entire preserved ecosystem, from the most delicate waterweeds to herbaceous understory plants, up to trees, and from the smallest most delicate baby fish, to the bones of several meter long predatory fish,” he said of the Waterloo Farm site.
“Fossil plants from the banks are also exquisitely preserved. These include delicate ancestors of horsetails, diverse lycopods (clubmosses), from small herbaceous species to 2m monopods, shrubby plants, ang giant woody trees up to 25m tall. These belong to Archaeopters, the first genus of woody trees.”
Gess said therefore Waterloo Farm provided evidence that all the major factors for vertebrate terrestrialisation (the subsequent move of our ancestors to land) were present in Southern Gondwana by the end of the Devonian.
“We now know tetrapods’s first step onto land could as easily have occurred in the Eastern Cape, as in Europe or America as previously supposed,” he added.
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This article was first published in Talk of the Town, April 10, 2025. The newspaper serving the communities of Ndlambe and the Sunshine Coast, with a weekly wrap of Makhanda news, is available at stores from early on Thursdays.
