Research has to be carried out to establish the exact age of the remnants. Picture: Wild North Fishing Club

Is it a mesosaur? Or some other kind of dinosaur? No-one is quite sure yet. Siberian zoologists are rushing to the site to extract the crocodile-like remains before they are covered by ice and washed away in the spring floods next year.

Intrepid tourists from the Wild North Fishing Club found fossil as they rafted on the Ruta-Ru River.

'The boat of our group member Oleg Yushkov bumped against something. It was not very deep there and he could discern a stone looking like the head of a prehistoric animal', said the club's chairman Yevgeny Svitov. 'He made a photo of the discovery and showed it to us. One source claimed it had a 'toothy grin'.

'We were at first sceptical about his find, saying there could not be any mesosaurs on Yamal,' he said.

However, Yushkov sent his photos to Moscow scientists who confirmed that this is the fossil of a mesosaur who had lived about 150 million years ago.'

He admitted: 'Research has to be carried out to establish the exact age of the remnants.'

Is it a mesosaur? Or some other kind of dinosaur? Picture: Wild North Fishing Club

Some sources say that mesosaurs or 'middle lizards' - inhabited the earth roughly 299 to 270 million years ago, long before the estimated 150 million years of this specimen. Intriguingly, he said without further explanation: 'We have information that in the upper reaches of the (Yamal) river there can be a dozen such finds.'

Pavel Kosintsev, head of the Zoological Museum of the Institute of Plant and Animal Ecology in Yekaterinburg, said: 'I was very surprised to receive these pictures which perhaps shows a dinosaur skull. I cannot yet say, is this really an ancient reptile. It is necessary to carefully examine the object.

'But, judging by the photographs, I acknowledge that there are dinosaurs with sharp teeth and a large skull'.