Discovery of old 'wrinkle-face' in the Sahara throws new light on the world's early history

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Even by the low standards of the dinosaurs, this one would not win a beauty contest. Its complexion resembled a wrinkled prune, its breath smelt of rotting meat and it had an unseemly habit of dining on its dead cousins.

Even by the low standards of the dinosaurs, this one would not win a beauty contest. Its complexion resembled a wrinkled prune, its breath smelt of rotting meat and it had an unseemly habit of dining on its dead cousins.

Yet the discovery of Rugops primus - which means "first wrinkle face" - in a remote region of the southern Sahara desert has thrown into question how and when the continents first formed from a single landmass more than 100 million years ago.

Palaeontologists believe that the discovery of Rugops in the Sahara shows that there must have been a land bridge between Africa and South America that survived surprisingly late in the history of the Earth.

A study published today in the journal Proceedings of the Royal Society shows that Rugops belongs to a class of dinosaurs called the abelisaurids which until now were virtually unknown in Africa but comparatively common in South America, India and Australia. An African abelisaurid suggests that Africa itself was still part of the much bigger, southern continent of Gondwana long after it was thought that the two land masses had broken apart as a result of continental drift.

Rugops primus was a typical meat-eating dinosaur. It walked on its two hind legs, measured some 30 feet long and had a short, round snout and a jawbone packed with small, rather delicate teeth.

According to Paul Sereno, a palaeontologist at the University of Chicago who led the expedition that made the discovery, the new dinosaur's most distinguishing feature was its head, or more exactly its wrinkled face.

The skin of the creature's head had a tough covering of scales or surface armour and it must have been riddled with arteries and veins that left a patchwork of grooves on the surface of the skull's bone. Two neat rows of seven holes are visible along the creature's snout which served no obvious purpose, except perhaps as anchorage points for something large and ornamental on the dinosaur's head, Professor Sereno said.

"It's not the kind of head designed for fighting or bone-crushing. This may have been a scavenger with head gear."

Instead of bringing down its prey with its enormous jaws, Rugops probably used its somewhat vulnerable head to pick at carrion rather than having to fight aggressively with other animals for its food, he said. "It's really a beautiful intermediate species of the group [of dinosaurs] that later evolved into the first horned predators."

A jawbone belonging to a specimen of Rugops was spotted in 2000 by Hans Larsson, a member of the expedition, who was scouring the dry sand dunes near Niger's Ténéré Desert for the fossilised signs of past life.

Just two feet away from the jaw, the scientists unearthed the rest of the partial remains of the creature's massive skull. "It was hard to see which end was the front, but we quickly realised we were looking at a brain case, and that it was probably an abelisaur - a huge find," Professor Sereno said.

This part of Africa today is a dry desert where daytime temperatures can soar to 49C but 100 million years ago it was rich in prehistoric life that lived in and around a swamp of rivers that were fringed with dense vegetation.

Professor Sereno has already made some important discoveries at the same site with the help of the corrosive desert winds that blow away the topsoil to reveal crucial clues, such as a jutting jaw bone or a single dislocated tooth.

In 2001, for instance, he announced the discovery of a giant crocodile which grew up to 40ft and had a set of 6ft jaws armed with more than 100 teeth.

"Supercroc", as he remarked at the time, was so big it not only walked with the dinosaurs, it ate them.

The latest find might not be as dramatic in terms of prehistoric freaks but the existence of Rugops in this part of the world demonstrates that 100 million years ago, Africa had yet to become a continent in its own right. For Professor Sereno and his colleagues, Jeffrey Wilson and Jack Conrad, the discovery of a member of the abelisaurus group in the heart of Africa suggests that there must have been a continuous land bridge connecting Africa, South America, Antarctica Australia and Asia at around this time.

They have dated Rugops to about 95 million years ago. Until this find, it was thought that Africa had already split away as part of the "Africa first" model of how the Earth's continents formed from a single primordial land mass some 140 million years ago.

The wrinkle-faced meat-eater clearly belonged to a class of dinosaurs that had family connections as far away as South America and Australia. This strongly suggests that a land bridge with Africa was retained many millions of years after it was supposed to have disappeared, said Professor Wilson, who is based at the University of Michigan.

"Until the continents fully separated, dinosaurs like Rugops and other animals used narrow land bridges to colonise adjacent continents and roam within a few degrees of the South Pole," Professor Wilson said.

Angela Milner, a dinosaur specialist at the Natural History Museum in London, said the discovery of Rugops does not radically alter the way the continents are believed to have formed, but it does give a better indication as to when Africa finally split away. "The evidence they present does argue for an intermittent land connection between northern South America and western Africa," Dr Milner said.

Whatever other secrets it yields, the wrinkle-faced dinosaur may at least help to explain when a separate African continent can be put on the map.