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Major new dinosaur unveiled Print E-mail
12 November 2009

The Aardonyx celestae dinosaur as it would have looked

Spion Kop is fast becoming South Africa’s Jurassic Park with the discovery of Earth Claw, which roamed in the northern Free State in that era.

A NEATLY arranged collection of bones on a table doesn’t mean much to the untrained eye and brain, but it is explosive in the right hands. In this case, the bones represent “Earth Claw”, a significant new dinosaur discovery found in the northern Free State.

The 183 million year old bones belong to Aardonyx celestae
The 183 million year old bones belong to Aardonyx celestae
A vegetarian dinosaur called Aardonyx celestae, dating back between 200 million and 183 million years – in the early Jurassic period – has been unearthed and announced by the University of the Witwatersrand. It was about seven metres long.

“This species is important, as the Aardonyx was an animal close to the common ancestor of the gigantic sauropod dinosaurs,” says Dr Adam Yates, a palaeontologist from the Bernard Price Institute for Palaeontological Research at Wits.

Written up in a paper published in the Proceedings of the Royal Society, entitled "A new transitional sauropodomorph dinosaur from the Early Jurassic of South Africa and the evolution of sauropod feeding and quadrupedalism", it was published on the same day as the announcement was made - Wednesday, 11 November.

Whereas the area in which it was discovered is known for its sauropods, the new discovery is a prosauropod bipedal creature which lacked specific dinosaur features, like straight limbs, small head, and huge barrel chest supporting a big gut.

Sauropods walked on all fours, could grow up to 40 metres long and weigh 100 metric tons, and had small heads with broad jaws for bulk feeding. The new discovery is an intermediate dinosaur, with a narrow, pointed jaw.

Aardonyx gives us a glimpse into what the first steps towards becoming a sauropod involved,” says Yates.

In addition, the fossils demonstrate that all the weight of the animal was taken on the inside of the foot, like a sauropod.

The Karoo basin where the excavations have taken place
The Karoo basin where the excavations have taken place
“What Aardonyx shows us, however, is that walking quadrupedally and bearing weight on the inside of the foot is a trend that started very early in these dinosaurs, much earlier than previously hypothesised,” says Dr Matthew Bonnan, a vertebrate paleobiologist in the department of biological sciences at Western Illinois University in the US, and a co-author of the paper.

“The bones of the forearm are shaped like those of sauropods – this means that the forearm and hand could bear weight and that Aardonyx could drop on to all fours as well as walk bipedally."

Earth claw
Aardonyx means “earth claw” – “aard” being translated from Afrikaans to mean “earth” and “onyx” being the Greek for “claw”. The species name celestae is an acknowledgement of the work of Yates’s wife, Celeste, who spent many hours chipping away the rock from the fossils. They are some of the first bones to be discovered in the town of Senekal, near Bethlehem. The discovery was made on a farm at Spion Kop in the Karoo basin.

The discovery was originally made by a Wits postgraduate palaeontology student, Marc Blackbeard, who began excavating two sites five years ago, under Yates’s leadership.

Yates acknowledges the work begun by James Kitching 20 years ago, when he discovered these “bone beds” on the site, but admits that the team did not expect to find anything “of this magnitude”. Kitching discovered a single dinosaur vertebra which was never taken further.

On the first day of excavation large bones were discovered. Sufficient bones – particularly the skull, vertebrae and back legs – have been found to piece together the new dinosaur.

“The dinosaur had a wide-gaping mouth, bracing joints in the back vertebrae that made the backbone rigid enough to support great weight and a forearm and hand capable of grasping and supporting weight,” says Yates. “Growth rings in the rib and shoulder blade sections show that Aardonyx was not full grown – it was probably less than 10 years old when it died near a river or stream.”

He says that the Aardonyx probably walked on its hind legs but could drop on to all fours when necessary. “It had flattened feet with large claws that supported body weight on the inside of the foot and a robust thigh bone [femur] for supporting weight.”

Cause of death unknown
He indicates that it is not known how the dinosaur died, but it is possible that the cause of death was a change in climate. Although the Karoo would have been dry and arid, the area in which the Aardonyx lived was lush and green – a palaeontological oasis.

Yates says that the Aardonyx was one of three new dinosaurs discovered in the area - but there will be a two- to three-year wait for the announcement of the others. Some 600 bones have been uncovered on the Spion Kop hill.

The new discovery adds to our knowledge of how the transition from bipedalism to quadropedalism occurred, he says. It was not a smooth transition. “Evolution is a messy, complicated affair. The shifting of weight-bearing was much earlier than we thought.”

The paper was written by several scientists besides Yates: Bonnan; Dr Johann Neveling, a geologist at the Council for Geosciences in Pretoria; Dr Anusuya Chinsamy, a Wits graduate and a vertebrate paleohistologist at the University of Cape Town; and Blackbeard, a graduate student at the Bernard Price Institute.

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