Museum scientists have begun to unpack the fossilised skeleton of what is probably a large sauropod discovered in Africa.
Natural History Museum palaeontologists are working on the 160-million-year-old fossil to determine exactly what it is. The work could take up to a year.
The event was filmed by CBBC's Blue Peter.
The partially complete skeleton, comprising the backbone, legs, ribs and teeth of the animal, was found in Niger, Africa, in 1988.
Sauropods were the biggest animals ever to walk the Earth. The leg bone of the find measures about 1.4m, which means this animal was particularly big.
An expedition to the Sahara desert discovered the bones just below the surface of the ground. They are well preserved, possibly because the animal died in wet sediment, such as a river bed, and was covered over quickly, probably with mud.
The bones are now completely fossilised.
Better late than never: Preparator Mark Graham, who is working on cleaning up the dinosaur bones, finally fulfills a childhood dream of owning a Blue Peter badge.
During the millions of years since the dinosaur's death, minerals from the earth have seeped in and replaced the bone, turning it to stone.
As is usually the case with sauropod skeletons, there was no skull among the bones. The skull might not have been preserved for a number of reasons, one of which could be that it was carried away by a predator.
Museum palaeontologist Dr Paul Barrett said the fossilised bones are probably from the Middle Jurassic period, between 176 million and 160 million years ago.
Although they are most likely from a sauropod, the specific species is not yet known. It could be something completely new.
Before being transported to the Museum from Niger, the bones would have been stabilised with PVA glue and carefully wrapped in acid-free tissue, sacking and plaster of Paris.
Museum staff will now work at cleaning up the bones to decide exactly what they are.
This is only the second reasonably complete sauropod skeleton in the Museum's collection and will be invaluable as a research tool.
Mark Graham and Dr Barrett both said they were very pleased to be awarded Blue Peter badges for appearing on the programme.
Dr Barrett will be showing the lower jaw and teeth of the first T. rex fossil ever found at Science Uncovered at the Museum on 27 September. Science Uncovered 2013