A TEAM of Scottish archaeologists have recreated the face of the world’s oldest dog from fossilised remains found buried deep in a rock in Elgin. Using a revolutionary scanning technique, the team has been able to build a model of the mysterious dicynodont, or two-toothed dog, which roamed the Earth 250 million years ago and was an important link in the evolutionary chain between reptiles and mammals.

Like mammals today, the herbivore had learnt to chew by moving its lower jaw, although it still had two tusk-like canine teeth — used to root out food from the desert sands of Britain, which was then at the latitude of the Sahara desert.

A combination of modern medical scanning techniques and sophisticated engineering has allowed Dr Neil Clark, a fossil expert, to produce the world’s first "chewing" model of the dicynodont’s skull.

The fossil was discovered in 1997 when men working at a sandstone quarry in northeast Scotland noticed a curiously shaped hole in one large rock and put it aside. But the secret of the creature, whose skull had made the 25cm-long impression, was buried in the rock, which was stored away in Elgin museum. "The bone had dissolved, leaving a hole in the rock. In the past rubber would be poured in and we would break it open to discover whether there was a fossil inside," said Clark, a palaeontologist in the University of Glasgow, based at the Hunterian Museum. "But this technique is very rough, leaving gaps where the rubber does not flow. It also damages the fossil."

Clark began to experiment with scanning techniques, working at night in Glasgow’s Royal Infirmary. He began with CT scans, a type of x-ray. Dr Callum Adams, a radiologist, offered to help: "I was walking by to see if there were any emergency cases and helped Neil to produce his first 3D picture. Then I was hooked."

Unsatisfied with the fuzzy images, the pair began experimenting with Magnetic Resonance Imaging (MRI). The scientists experimented with different frequencies until they produced successful scans. From 200 2mm-thick "slices", Clark identified the sharp lines of the dicynodont’s skull — a creature with a head rather like a parrot, four legs, a scaly skin, but named an early dog because its relatives would evolve into the first mammals.

The next challenge was to make a model. Clark discovered that Laser Prototypes Europe, in Northern Ireland, had been working with its local hospital to turn MRI scans of human skulls into models that could be used in dental surgery. The result, according to Clark, is revolutionary and will be displayed at the Hunterian Museum later this year.