DINOSAUR expert Dave Martill stumbled across a 300-million-year-old marvel as he strolled along a beach.

Stepping over a rock, Dr Martill was stopped in his tracks by what looked like a piece of bone.

On closer inspection, he realised that a skull was contained within an 18in block of ironstone.

The chance find has now been confirmed as the discovery of a new species of giant amphibian that lived in the carboniferous era, before dinosaurs roamed the earth.

A 6ft-long creature, it looked like a large newt but had a wide row of teeth that made it a deadly predator.

Its existence has never been acknowledged until now and the creature has been named Kyrinion martilli after Dr Martill.

Dr Martill, a Reader in Palaeobiology at Portsmouth University, made the find at Whitley Bay, North Tyneside, near St Mary's Lighthouse, in 1993.

For the past ten years, Jenny Clack, a reader in palaentology at Cambridge University, has spent thousands of hours painstakingly whittling away the stone, using precision intruments such as dental drills.

She has now finally been able to confirm it as a new species and has published a paper proclaiming its discovery.

Dr Martill said: "The fossil is of global significance.

"It was a tiny window of opportunity that I was on the beach before the stone was washed out to sea and that a little area of bone was peeping out of the stone, which had protected the fossil."

The skull is still being held at Cambridge but will be moved to the Hancock Museum, in Newcastle.