The first discovery of a brain tumour in a dinosaur has revealed that they are indistinguishable from human tumours, suggesting the global disease has barely changed over 70 million years.

The new evidence was announced by researchers from the Black Hills Institute of Geological Research in South Dakota to a conference of the Society of Vertebrate Palaeontology in Minneapolis.

In related research, Bruce Rothschild and colleagues from the Northeastern Ohio Universities College of Medicine have published evidence of tailbone tumours in duck-billed dinosaurs, in the journal Naturwissenschaften.

Both types of tumours were found in bones from around 70 million years ago, and suggest tumours have remained unchanged since ancient times.

A thumb-sized brain tumour in the mighty meat eater, Gorgosaurus, a cousin of the infamous Tyrannosaurus Rex, must have caused a bad headache that left the 7.5m long giant stumbling for balance.

Black Hills Institute president Peter Larson discovered the mass inside the brain-case of an exhibit. He describes it as "very bizarre, dark material in the matrix that looks kind of like crumpled paper".

"I broke off a little piece and put it in a scanning electron microscope and basically bombarded it with X-rays to tell what sort of elements were there," says Larson.

Larson was unable to conclude if the brain tumour was the cause of death, however, "it almost certainly affected its balance and locomotor function," says Rachel Reams, a veterinary pathologist who examined the brain case.

In a much broader study, Bruce Rothschild and team used X-ray techniques to scan 10,000 dinosaur vertebrae from 700 museum specimens, ranging from Tyrannosaurus to Triceratops. The team found tumours only in hadrosaurs, or duck-billed dinosaurs, of which 97 individuals had tumours.

Most were tumours of the blood vessels, which are also present in one out of ten humans.

The results are significant in that the tumours found in the dinosaurs were identical to human tumours, suggesting that cancer has been around relatively unchanged for up to 100 million years.

"Diseases look the same independent of what critter is affected," says Rothschild. "If I showed [the dinosaur bones] to a pathologist, he'd make the same diagnosis."

Professor Mike Archer, Director of the Australian Museum finds the results extremely significant.

"They [dinosaurs] suffered like animals do today with the same diseases, and just like us they often get taken out by them," he told ABC Science Online.

"This technology for the first time enables palaeontologists to look inside bones. These are incredible tools that until now weren't available."

Tumours in dinosaurs have been found previously but this is the largest scale study done so far and suggests that there was a much higher incidence of cancer than previously thought. It is unclear why the tumours were confined to one group of dinosaurs - it may be either genetic or environmental factors, he says.

Although the researchers suggest that conifers which made up their diet may have been high in carcinogenic chemicals, Archer thinks that this is unlikely. Cycads, another favourite dinosaur food, is a more likely culprit, Archer says.

"Cycads contain some of the most powerful carcinogens known to mankind. There's a lot of food value in the cycads, you can't blame the dinosaurs for having a munch, but it's not only a powerful carcinogen, it makes you violently ill."

"Understanding what causes tumours in wild and extinct animals might help treat and prevent them in humans," says Rothschild.

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