A dinosaur reconstruction effort that began with half a giant thigh bone discovered in South Africa is puzzling palaeontologists, who think they might have stumbled across a new species.

After 20 years of patient collection, researchers finally have enough fossils to put together a complete picture of a 14-tonne creature from the sauropoda group of dinosaurs, characterised by their small head, long neck, long tail and elephant-like gait.

The new specimen, nicknamed the Highland Giant, is thought to be the largest animal ever to roam the Karoo region in South Africa.



“We’re not sure if it’s a new species, or if it’s the biggest specimen ever found of a species we already know. But it’s important either way, because we didn’t know that these dinosaurs could get this big,” said Jonah Choiniere, who led the excavation team for South Africa’s Evolutionary Studies Institute.



While sauropods in other parts of the world could weigh up to 80 tonnes, the Highland Giant was nearly a third larger than any others discovered in South Africa. “It’s the size of two African elephants stacked on top of each other,” said Choiniere.

Facebook Twitter Pinterest An artists’ impression of two diplodocus dinosaurs, one of the species in the sauropoda genus. Photograph: Corey Ford/Alamy

The Highland Giant lived 200 million years ago near a small river that today forms part of the Lesotho-South Africa border.



The environment was semi-arid, in many ways like South Africa today, although much flatter. The dinosaur was herbivorous, gulping plants whole and fermenting them in its massive stomach. It probably died on the banks of a river.



Facebook Twitter Pinterest Half a thigh bone from the Highland Giant. Photograph: Simon Allison/The Guardian

The first fossils were discovered more than two decades ago during construction for the Lesotho Highlands Water Project, a network of dams. The bones were embedded in rock more than 20 metres (65ft) up a cliff in a valley formed by erosion. They could only be accessed by an arduous climb up the cliff face, and palaeontologists had to drag their power tools along with them to cut through the rock.

As Choiniere and his team take the bones for more detailed analysis, they will be looking to understand where the Highland Giant fits into the sauropods’ evolutionary history. The team is also trying to determine whether it walked on two legs or four.



The new dinosaur is the second significant discovery this year announced by the Evolutionary Studies Institute, which in September was behind the unveiling of the homo naledi fossils, said to be a new species of human relative.



The dinosaur find was announced in a ceremony to mark World Science Day at the University of the Witwatersrand on Tuesday.