Graaff-Reinet fossil making waves

Having rested for 30 years in a school quadrangle, “the savage one”, mankind’s great (to the nth degree) grand-uncle, has moved to the Graaff-Reinet Museum where he is making waves.

According to a US-based palaeontologist affiliated to the museum, Lexie — as pupils and staff at Union High School knew him, named after former staff member and discoverer Lex Bremner —  is uniquely placed to tell us a whole lot about our ancient past.

Graaff-Reinet Museum research partner Dr Christian Kammerer, currently at North Carolina Museum of Natural Sciences in North Carolina in the US, said he was elated.

“This specimen is incredible and of great scientific value.

“It is the most complete fossil of Rubidgea ever discovered, being the only one to preserve the spinal column.

“Other Rubidgea specimens are just isolated skulls.

“Lexie includes a complete skull, the whole spinal column up until the tail, and the right hip bone.”

He said the fossil was officially Rubidgea atrox.

“In Latin, that means  “Rubidge’s savage one”, named after Dr Sydney Rubidge of Wellwood Farm near Graaff-Reinet, who discovered the first specimen in the 1930s.

“It was the top predator of the late Permian Era in SA and one of the largest representatives of a group of therapsids called gorgonopsians, named after the horrific gorgons of Greek myth.

“Gorgonopsians were found in what is today Southern Africa and Russia and nowhere else.

“They were saber-toothed carnivores and they used powerful canines to slice open and feed on plant-eaters.”

Kammerer said based on geological mapping of the Graaff-Reinet area, it was known that Lexie was collected in Permian rocks corresponding to the Cistecephalus Assemblage Zone, named after a small burrowing therapsid.

“A Wits University team, including Prof Bruce Rubidge of Wits University — the grandson of the palaeontologist who discovered Rubidgea — demonstrated that this zone is roughly 255 million years old.”

Union High headmaster William Pringle said the fossil was donated to the school more than 30 years ago by Bremner, who was the school groundsman and caretaker at the time and also a renowned amateur fossil hunter.

“Lexie was on display in the quad of the school as Bremner wanted to remind pupils and staff alike of the appearance of the possible common ancestor to all mammals, including themselves.”

He said he believed the fossil would be better off in the museum where experts could care for it and conserve it for posterity.

“The school also wishes the fossil to be more accessible for viewing by the general public.”

Kammerer said the bulkiness of Rubidgea was indicative of a healthy ecosystem capable of supporting predators of various shapes and sizes.

“It lived during the last stable portion of the Permian, before the eruption of super-volcanoes which led to runaway global warming and caused the mass extinction.”

He said Lexi was still encrusted with some rock and this would need to be cleaned off before study of the fossil could begin in earnest.

“We are hoping to learn whether Rubidgea was capable of running down prey or was more of an ambush predator.

“It will also help to resolve the family tree of gorgonopsians, which are a greatly understudied group.

“Therapsids are the ancestors of mammals, and the Karoo record was hugely important in the 20th century for demonstrating how these reptilian creatures evolved into mammals like ourselves.

“With that said, these are truly ancient animals, from well before the age of the dinosaurs, never mind hominids.

“Gorgonopsians were a dead-end of the therapsid line, which died out in the worst mass extinction of all time, the end-Permian geological cataclysm. 

“Their distant relatives the cynodonts survived, and they are our ancestors.

“The gorgonopsians are perhaps better thought of as great (to the nth degree) grand-uncles.”

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