The first dinosaur fossil discovered in Norway is also the deepest one that has been found anywhere in the world.
To find a dinosaur at this depth is remarkable (Image: Jorn Harald Hurum)
The 195-210-million-year-old specimen was found 2.3km (1.4 miles) below the floor of the North Sea by an offshore oil drilling platform.
Norwegian palaeontologist Jorn Harald Hurum, from the University of Oslo, identified the fossil as the knucklebone of a plateosaur.
Details of the discovery are to appear in the Norwegian Journal of Geology.
"It's the first time a dinosaur bone has ever been found in such a deep core," Dr Hurum told the BBC News website.
Marine reptile fossils have been found in some previous North Sea drill cores, but to find a terrestrial animal at such a depth is rare.
"To drill through a terrestrial animal is much rarer because there are so many more marine sediments there," Dr Hurum, assistant professor of vertebrate palaeontology at Oslo's Natural History Museum, explained.
The crushed knucklebone was identified in a long cylinder of rock drilled out from an exploration well at Norway's Snorre offshore field.
The geologists who drilled the core spotted the curious specimen in 1997; but they were discouraged by colleagues who thought it was plant matter and tucked it away in a drawer.
Only in 2003 did they pass the specimen to Hurum, who thought it looked like a dinosaur.
After consulting palaeontologists at the University of Bonn in Germany, a microscopic examination of the specimen showed it to be identical in structure to bones from a Plateosaurus species.
Plateosaurus fossils are known from across Europe
This dinosaur is the most common type found in Europe. At the time it lived, there was a desert between Norway and Greenland crossed by meandering rivers.
"We knew there was food there, so something must have been eating it; but we didn't know what animals were there," Dr Hurum said.
Dr Hurum describes himself as Norway's only dinosaur researcher. Successive ice ages have eroded dinosaur-bearing rocks in mainland Norway.
But the scientist thinks fossils could be found on the northern island of Spitsbergen.