Dinosaur tracks are longest in Britain

The longest set of fossilised dinosaur tracks in Britain has been uncovered at the bottom of a limestone quarry in Oxfordshire where they had lain undisturbed for 168 million years.

The longest set of fossilised dinosaur tracks in Britain has been uncovered at the bottom of a limestone quarry in Oxfordshire where they had lain undisturbed for 168 million years.

Running for up to 200 metres over the floor of the quarry, the footprints are among the last remnants of a lost world where dinosaurs roamed the muddy shores of an ancient ocean.

Scientists from Oxford University's Museum of Natural History have completed a detailed survey of the footprints. They were first discovered by a Birmingham schoolteacher three years ago.

Since then, they have found that the tracks, whose positions have been mapped precisely by global positioning satellites, are the longest in Britain and possibly Europe. They rival some of the great "dinosaur freeways" of America, which are believed to have been used during mass movements of the extinct leviathans.

Philip Powell, assistant curator of the museum's geological collection, said that the presence of the trackways was initially kept secret because of the fear that public interest in them would disturb the landfill operations at Ardley Quarry, 13 miles north-east of Oxford.

The site covers a quarter of a square mile of Jurassic limestone formed at a time when Britain was in the tropics and a shallow area of sea and lagoons extended north and west into what is now the Cotswolds.

Mr Powell said two sorts of trackways were present. One was composed of three-toed footprints up to 80cm (31.5in) long and 65cm wide, spaced up to two metres (79in) apart.

Clawmarks seen in some of the footprints, and their shape and size, suggest they belong to a bipedal carnivorous dinosaur called Megalosaurus, which is known to have lived in the area at that time.

The second set of trackways were made by an animal whose front feet created kidney-shaped prints about 40cm long. The rear footprints are semicircular and are about 60cm long and 56cm wide.

Mr Powell said those tracks were probably made by a large, ponderous herbivore called Cetiosaurus, which grew up to 15 metres long. Fossil bones of this "whale lizard" were first found in Oxfordshire limestone some 200 years ago.

Cetiosaurus resembled the more familiar Brontosaurus, with a long neck and tail andpillar-like legs. "This animal walked on all fours, in such a way that the prints produced by the back feet were usually superimposed on the front ones," Mr Powell said.

"The great weight of the animals is indicated by the ridges of mud - now transformed into limestone - that form a rim at the front of the footprints," he said.

The tracks in the Ardley Quarry criss-cross and there are no signs that the animals were moving in any particular direction or that they interacted with each other while moving.

The excavation team in Oxford had taken moulds of the better-preserved footprints at Ardley before they were covered over with landfill waste, which would preserve the trackways better than leaving them fully exposed, Mr Powell said.

"It is difficult economically to stop the operation. Covering them up is a good way of preserving them. It's a shame but it would be too costly to preserve them any other way."