A T. rex fossil may be the most expensive dinosaur ever sold.

Cassandra Hutton argues that Gus’s price is an example of how important it is.

“Gus is one of the largest and most complete T. rex ever found, 61% of the bones have been identified – generally you find half the skeleton, which is a scientific discovery,” she said.

The condition of the bones also provides a deeper understanding of what kind of life this creature would have had.

“There is a large bite mark on the top of the skull that may have been left during the battle. The bones are broken – some of the ribs, you can see big bumps where they were broken and healed.”

Cassandra Hatton said she spent months reaching out to museums around the world to get them to participate in the auction. She wants “something scientifically important to put into public trust.”

But she said the price should reflect the time, skill, cost and risks involved in recovering the dinosaurs. “For a lot of digs, some of these people are living hand-to-hand. They’re not rich people.

“They have to invest their own money. Not billionaires digging them up.”

But billionaires buy them.

Apex, Stegosaurus, was auctioned to Kenneth Griffin, founder and CEO of hedge fund Citadel. Griffin has since loaned Apex to the American Museum of Natural History for four years.

Museums have long relied on wealthy bequests, loans or donations of artefacts to build their science and art collections, says Dr Smithwick, who recovers and sells fossils by profession.

But unlike art classes, relying on the philanthropy of private estates is a big hurdle when it comes to fossil research.

Most respected scientific journals will not accept any research done on a sample in a private collection. Almost non-existent for the scientific world.

The argument is that scientists should be able to look at the fossil again over many years – to agree and disagree, to confirm their findings as other specimens come out.

“What happens (if) if that person is bored of them, if he dies, he gets a divorce. And there were many cases where the specimens were in private collections, and the scientific description of them and (which) went beyond,” said Professor Maidment from the NHM.

“So now it’s not just science.”