BBC Science correspondent James Wilkinson on the remarkable discovery

Footprints up to three feet long were found in a limestone quarry, including one of a dinosaur over 80 feet high.

"There is no comparable site in the world," said Swiss paleontologist Christian Meyer.

His team has been studying the site for the last two months, after a Bolivian scientists found it two years ago,

Skeletons have also been found

The area is situated in a limestone quarry, with the prints embedded in the mountainside, at inclines of up to 70 degrees.

It was once a lake bed has been pushed up by geological activity over milllons of years to become a hillside.

The prints are whole and look like the dinosaurs might have been walking in a mud lake.

Dinosaur experts are expected to converge on the area to study the remarkable collection.

Scientists have identified several different species including it is thought a tyranosaurus.

Dinosaur skeletons have been uncovered, including one or two giant dinosaurs which stood more than 80 feet high.

Remains of fish, crocodiles and turtles have been found too, supporting the theory that the valley was a large lake where the dinosaurs came to bathe.

Scientists have warned that the prints could disappear altogether within 20 years because of rain and wind if efforts are not made to protect them from erosion and destruction.

Limestone mining nearby makes the area even more precarious.

Scientists are calling on the Bolivian Government to make sure it is protected.