'Stan' The T. Rex, Sold For World Record Price
The 67-million-year-old fossil went to an anonymous bidder in the sale organised by Christie's in New York.
The guide price had been $6-8m, but this was rapidly surpassed as the online auction progressed.
Stan's hammer price smashes the $8.4m record paid for the T. rex known as "Sue" in 1997.
That particular specimen went on display at the Field Museum in Chicago. Where Stan is headed is uncertain, however. The fear, as always, is that it could disappear into a private collection never to be seen again.
While Christie's declined to divulge the name of the new owner, the company's James Hyslop said some further details about the dino's future could emerge in the next few days.
The actual winning bid was $27.5m, but commission and other additional costs took the final price to $31.8m.
Stan carries the name of its discoverer, the amateur palaeontologist Stan Sacrison.
He first saw the dinosaur's remains in 1987, weathering out of sediments in the famous fossil-yielding Hell Creek Formation in South Dakota.
The bones were positioned about 16m below the Cretaceous-Paleogene (K-Pg) boundary - the geological horizon that records the impact of an asteroid on Earth, and the demise of three-quarters of all animal and plant species, some 66 million years ago.
Stan is regarded as one of the finest T. rex specimens in existence.
It comprises 199 bones - about 70% of a complete skeleton - which have been subjected to a battery of tests and investigations. Damage to the skeleton suggests the dinosaur was involved in a number of battles during its life.
"Stan rapidly became the 'Stan-dard' for T. rex, given there are so many casts of this extraordinary fossil that have been sold all over the world," commented British dinosaur expert Prof Phil Manning who has worked on the specimen.
"If you have looked at a T. rex in a museum, the chances are it was a cast of Stan. The skull is possibly the best preserved, given it was found as isolated elements, carefully prepped and beautifully reconstructed.
"I am keeping my fingers and toes crossed that this remarkable fossil stays in the public domain for all to enjoy," the University of Manchester scientist told BBC News.
Stan had been on display at South Dakota's Black Hills Institute of Geological Research since the late 1990s, but the Hill City company was ordered in 2018 by a court to release the specimen for auction.
With the sale comes certain intellectual property rights, but the new owner has been denied permission to make future casts or 3D prints, or to sell related merchandise online.