It is 150 -- 155 million years old and the first dinosaur of its kind to be discovered in such good condition.
But how much is a teenage fossil worth?
Paleontologists will find out Wednesday as an incredibly rare juvenile allosaurus goes under the hammer.
The 9ft-long carnivore found in Wyoming and nicknamed "Young Al" is only the second juvenile allosaurus specimen to be found.
"This is a very exciting but nerve-wracking time for us," Rupert Werff, director at auctioneers Summers Place
, told CNN.
"The first juvenile allosaurus was just a couple of limb bones and three ribs, so this is by far the most intact specimen."
The young dino was found by a professional fossil hunter, who asked to remain anonymous, in the Morrisson Formation, a rich fossil bearing area.
But despite the hefty price tag, the anonymous owner is unlikely to profit from the excavation.
Werff said: "Dinosaur excavation is a pretty expensive business. The excavation took a big team three years to complete."
"Fossil hunting is not something you ought to do if you want to make a profit."
Other items on sale at the auction house in Sussex, southern, England, include an enormous elephant bird egg, a wooly mammoth skull and a stegosaurus tail spike.