An "exceptionally rare" almost-complete skeleton of a young dinosaur is expected to fetch up to half a million pounds when it is auctioned off later.

The remains of the Allosaurus, one of the largest dinosaurs of the late Jurassic period, are believed to be the most complete juvenile of the species discovered so far.

The skeleton, known as Little Al and estimated to be up to 155 million years old, will go under the hammer at Summers Place Auctions in Billingshurst, West Sussex.

Relatively complete dinosaur skeletons are "extremely rare", the auctioneers said, with those of young dinosaurs even more so.

Pieces of the Allosaurus were first discovered five years ago near a quarry in Wyoming in the United States, scattered over a wide area, and among the remains of a Sauropod dinosaur.

Experts have previously said the juvenile specimen has "the cute factor" and may attract buyers wanting an unusual statement piece for their living room.

Rupert van der Werff, director at Summers Place, said: "The Allosaurus, together with the T-Rex, has become the quintessentially large, carnivorous dinosaur in western popular culture.

"Given the size of this Allosaurus it also adds the cute factor and may not just attract interest from museums but could also be the wow factor in a luxurious living room."

Evolution curator Errol Fuller said: "Some of the bones are gigantic, some are tiny, but all must be approached with the same degree of caution to ensure that nothing of importance is overlooked.

"Once a bone, or series of bones, is located, the exact position is carefully mapped so that vital evidence is not lost when the specimens are finally removed from the ground."

The lot, which can only be bid on by phone or in person, has an estimated price of between £300,000 and £500,000.