“It’s like opening a Christmas present,” Lindikhaya Sandi said this week, at the prospect of starting to prepare the fossil remains of what could be a new species of dinosaur.
Sandi and Albany Museum palaeontologist Billy de Klerk – both are from Grahamstown – were among the fossil experts who last week successfully removed the remains of a large dinosaur found near the top of Barkly Pass, south of Lesotho.
Team leader, University of the Witwatersrand palaeontologist Jonah Choiniere, said it was “highly likely” that the animal, which is at least 190 million years old, was a species new to science.
The dinosaur was discovered in 2010 by farm manager Johan Erasmus. He took a break while herding sheep along the gravel road that runs from Mountain Shadows hotel near the top of Barkly Pass to Moshesh’s Ford and realised he was sitting on the end of a massive bone.
Using a jack hammer, a power saw and old-fashioned muscle power, the team uncovered what the scientists think was probably a 190 million-year-old 80-ton monster.
In two sessions of excavation, the first in May this year, the team removed about two tons of rock to uncover the tail bones, left back leg, and a set of at least seven rib-like gastralia. The rest of the skeleton has not been preserved.
But the bones that were recovered, said Choiniere, were enough to place the creature in the broad family of plant-eating dinosaurs called sauropodomorphs.
The team also discovered among the bones the broken-off teeth of smaller, meat-eating, dinosaurs, which Choiniere said must have been scavenging the carcass after the animal died.
He said the dinosaur when alive would have been some eight metres long, with a fairly long neck, a barrel-like body on stumpy legs, and a long tail that swung in the air as it moved, rather than dragged on the ground.
It was likely to be an ancestor of the “true sauropods”, vegetarian dinosaurs which reached a size of 70 to 80 tons and because of their massive body size walked on all four legs, rather than on the back two, as did the early dinosaurs in their family tree.
The Barkly animal, said Choiniere, was likely to have been well on the way to walking on all fours.
“We don’t have a forelimb, unfortunately, but this is an animal that would at least be touching down with its forefeet quite often as it feeds or as it’s moving slowly across the landscape,” he said
“Everything in this part of the evolutionary tree is very important, because we have only a few specimens spread across what is a very long lineage. Every piece of evidence we can add to that greatly improves our knowledge of how fast quadrupedality [four-legged walking] evolved, how fast large body size evolved.”
He said it was “highly likely” that the dinosaur would turn out to be a new species.
Most of the dinosaurs found in this geological layer, known as the Elliott Formation, were relatively small animals, such as the Heterodontosaurus and Massospondylus.
“It’s very rare to find anything big up here. This is probably the biggest animal ever found in the upper part of the Elliot.”
In recent years De Klerk, from Grahamstown’s Albany Museum, has recovered a number of Heterodontosaurus and Massospondylus skulls and other remains from the area around Rossouw village.
Choiniere said it was possible to put an age of at least 190 million years to the Barkly dinosaur because scientists could accurately date the Drakensberg lavas sitting some distance above the layer of rock in which it was found.
“Those we know are around 185 million years old. Because it’s lower than the lavas, it must be older than them.”
He said the landscape then had been a dry environment, with wind-blown sand dunes, patches of rocky ground covered with scrub, and green belts around a few established rivers.
It appeared that the dinosaur died on a pile of wet sediment at the edge of a pool or stream. Because it was a big animal, it had sunk into the sediment slightly, which was why there was a well-preserved foot under the leg bones.
As it decomposed, it was scavenged by smaller, meat-eating dinosaurs belonging to the theropod family.
“I’m sure of that because of the amount of theropod teeth that we found around it,” he said.
The team had recovered about a dozen teeth, ranging in size from a little less than a centimetre, to five or six centimetres long.
The different sizes meant the teeth either came from different species of theropod, or from juveniles and adults of the same species.
Choiniere said it was common to find the broken-off teeth of scavengers around dinosaur carcases. “It’s like jackals trying to tackle a rhino carcass,” he said.
He said that after the theropods had fed, the water rose and covered the rear end of the carcass with mud and gravel. The front end was either washed away, or carried off by other scavengers. Later, the site was capped by a layer of reddish mud from a major flood, sealing off the bones to be uncovered and discovered millions of years later.
Under Choiniere’s supervision, the team, which included three of his graduate students from Wits, used mallets and chisels to expose the top of the bones, and painted them with a glue-like substance called paraloid to protect the more fragile portions.
Then with the power saw and jack hammer, they removed surrounding sandstone to leave the bones embedded in five large blocks of rock.
They covered the blocks with a thick jacket of reinforced plaster of paris, to protect the specimen as it was being moved, and finally with chisels knocked the plaster-covered blocks off their rock base.
The work was hot and dusty, but the team was rewarded with part of a left thigh bone, the shin bones and foot (with a massive claw) from the same leg, and the gastralia.
Gastralia are rib-like structures that supported the abdomen of the animal. Gastralia are today found in crocodiles and birds, a sign that both evolved from dinosaurs.
Choiniere said they recovered about half of the 60 or 70 vertebrae that would have made up the creature’s tail. The rest of the tail bones had been broken off and lost, probably during road construction.
He said the plastered lumps would go to the Albany Museum to be prepared. Most of the rock would be painstakingly removed from the bones so that scientists could look at the fossil from all sides and get a better idea of its anatomy.
“If it’s a new species we’ll give it a name,” he said.
Sandi, who is one of the museum’s preparators, said he was very excited at the prospect of working on the fossil.
“When you take it out of the jacket, it’s like opening a Christmas present,” he said. “You’re the first one to open it, and the first one to see inside it.”
He said it would probably take the museum’s team of preparators – each working on a different section of the fossil – about six months to complete the job.
During the first session of excavation, in May, someone removed the exposed end of the thigh bone from the site after the team had packed up for the day.
Despite a police investigation and a R1 000 reward offered by retired Barkly farmer Selby Vorster, who first reported the fossil to De Klerk, it has not been recovered.