SANRAL plays key role in preserving natural heritage

The South African National Roads Agency SOC (SANRAL) has contributed to the body of palaeontological knowledge through its support of the discovery and preservation of the fossilised remains of life from a 360-million-year-old marine Eastern Cape ecosystem, the agency announced today.

SANRAL'S involvement with Late Devonian research goes back to 1999 when it assisted Dr Robert Gess to rescue 30 tons of fossiliferous shale ahead of roadworks at Waterloo Farm, 2km south of Grahamstown in the Eastern Cape.

New fossil findings from gradual excavation of these 360-million-year-old shales belonging to the Waterloo Farm estuarine lagerst"atte (exceptional fossil site) were published today in Science. Lead author, Dr Robert Gess of the Albany Museum in Grahamstown (who is supported by the DST-NRF Centre of Excellence in Palaeosciences based at the University of the Witwatersrand, and the Millennium Trust) teamed up with Professor Per Ahlberg of Uppsala University in Sweden to describe the finds.

Their research paper: "Tetrapods from the Devonian Antarctic Circle", helps to highlight the global significance of late Devonian research in the Eastern Cape.

"Whereas all previously found Devonian tetrapods have come from localities which were in tropical regions during the Devonian Period, the Grahamstown specimens represent species that lived in the Antarctic Circle and thus force a major reassessment of the origin of four-legged vertebrates," explains Gess.

"During the Devonian Period (360 million to 420 million years ago) the ancestors of all land-living vertebrates evolved from lobe finned fish. These creatures had traded their fins for four stubby legs but retained a tadpole like tail. About a metre long, they looked superficially like a cross between fish and alligators and lived in pools, lakes and lagoons where they probably inhabited the shallows. Shortly after the End Devonian Mass Extinction Event, their descendants moved onto land and gave rise to land vertebrates: amphibians, reptiles, birds and mammals, including ourselves," explains Gess.

"At SANRAL's inception in 1998, it became a priority to make the N2 road between Grahamstown and the Fish River safe. While surveying the geology through which the Waterloo Farm road cutting went, we were made aware that the area held elements of great importance to South Africa's history.

"Construction of the repairs was immediately halted and SANRAL brought in Dr Gess and his team to mine out 30 cubic metres of shale by hand. SANRAL then transported the shale to Bathurst, where Dr Gess began to steadily work through it in search of fossils," said Rob Damhuis, geotechnologist and project manager at SANRAL Southern Region.

"The results of the excavations were incredible, uncovering thousands of unique fossils which are of great international importance today. So far, the remains of an entire coastal estuarine ecosystem from 360 million years ago has been discovered," Damhuis said.

A further 70 tons of shale was similarly rescued in 2008, and to further assist with the fossil finds and help to preserve the shale, SANRAL built a shed next to Dr Gess's existing shed to store the shale blocks and protect the fossils from weather damage.

Dr Gess says he had always hoped to find remains of Devonian tetrapods at Waterloo Farm, even though the textbooks suggested it wasn't at all likely. "I read Dr Jenny Clack's book 'Gaining Ground' and familiarised myself with the skeletal transformations involved in the fish to tetrapod transition. I was splitting shale with my student Chris Harris when I found the cleithrum of Tutusius. I just knew that this was what I'd spent years looking for. I went all quiet and then abandoned what I was doing and went to fetch the literature just to double check. I'll never forget that afternoon.

"In South Africa, we have a really good evolutionary history preserved in the rocks, which now adds the emergence of animals with legs from fish, to a well-studied record of the evolution of mammals from reptile-like ancestors and development of the earliest humans. Our fossil heritage is world renowned.

"The fact that the tetrapods were found at the Waterloo Farm site gives us a really good picture of the environmental setting in which they lived. Of all sites in the world that have tetrapod remains, Waterloo Farm has the best record of what plants and animals were around the ecosystem that the tetrapods were living in," Gess added.

"This is the only site in the world that has tetrapod remains but also has soft tissue preservation. The rock shed that SANRAL donated has almost certainly preserved more remains of the bony parts of the Devonian tetrapods, but it is possible that further excavations might also reveal evidence of the non-bony parts, which are as yet unknown from anywhere," said Gess.

Sanral has continued to be interested in Dr Gess's Devonian research project and recently facilitated the discovery of further fossil sites. While monitoring controlled rock cutting explosions by SANRAL along the N2 between Grahamstown and the Fish River in 2016, Gess and his student Harris discovered new Devonian river mouth sites 20km east of Waterloo Farm. These sites help to fill out the picture of environments along the ancient high-latitude shoreline of Gondwana.

"It is important that the public is aware of this collaboration and is aware of the agency's support to preserve our natural heritage," said Mbulelo Peterson, SANRAL Southern Region Manager.

SANRAL's standard management plans contain guidelines for project managers who may encounter similar cases of palaeontological heritage, especially in areas where experts believe the potential for finds is high.

"In 2016, as part of a conservation plan for the N2 Wild Coast Road (N2WCR), we initiated our environmental management programme which is aimed at protecting the biological diversity and natural heritage of the Eastern Cape. As part of this programme we have already conducted palaeontological training for environmental and other personnel, to sensitise them to the potential for and tell-tale signs of palaeontological finds as well as to iterate what to do if such findings should occur," Peterson added.

Picture credited, Gess and Ahlberg (2018) A tetrapod fauna from within the Devonian Antarctic Circle. Science