Damien Hirst shark that sold for about $8m is fourth 2017 work dated to 1990s

A Damien Hirst shark preserved in formaldehyde that was purchased by American billionaires was dated to the 1990s even though it was not made until 2017.

The 4-metre (13ft) tiger shark, dissected into three parts, is the centrepiece of a luxury bar in the Palms casino resort in Las Vegas. It first appeared in the casino six years ago, with the title: The Unknown (Explored, Explained, Exploded), 1999.

However, an investigation by the Guardian has established that it was made in 2017, almost two decades after the date publicly ascribed to the work. The sculpture was bought by the billionaire brothers Lorenzo Fertitta and Frank Fertitta III, amid suggestions it cost around $8m.

Related: Damien Hirst formaldehyde animal works dated to 1990s were made in 2017

The huge shark is the fourth formaldehyde sculpture by Hirst now known to have been made in 2017, despite having been dated to the 1990s. The other three, made with a dove, a small shark and two calves, have in recent years been exhibited with 1990s dates in galleries in Hong Kong, New York, Oxford and London.

The revelation some of Hirst’s formaldehyde works were given dates that do not accord with the dates they were physically made has rocked the contemporary art world this week.

“Cases like this don’t help assuage doubts about the lack of transparency in the art world,” said Jo Baring, a former director of Christie’s auction house in the UK. “Hirst is an artist who wields so much power, he is much in demand by museums, who want to boost their ticket sales, and also collectors who want to own a touch of the stardust. But that power means that people are afraid to challenge or ask questions.”

Hirst did not directly respond to questions when asked about the tiger shark piece, The Unknown. Sources familiar with the creation of the sculpture said it was made in 2017 in preparation for its installation in the hotel.

When it was first unveiled to much fanfare in 2018, the previously unseen tiger shark was described by the casino as a piece from the 1990s. The “1999” date was contained in work’s title, which is typically provided by the artist, and included in promotional material.

Dates attributed to artworks are widely understood to refer to the year they were completed. However, in response to questions from the Guardian, Hirst’s company, Science Ltd, said the date the artist assigned to formaldehyde works did not represent the date they were made.

“Formaldehyde works are conceptual artworks and the date Damien Hirst assigns to them is the date of the conception of the work,” the company said. “He has been clear over the years when asked what is important in conceptual art; it is not the physical making of the object or the renewal of its parts, but rather the intention and the idea behind the artwork.”

Hirst’s lawyers later clarified that while using the date of conception in the title was the artist’s “usual approach” for formaldehyde works, he did sometimes use the date the sculptures were made. “The dating of artworks, and particularly conceptual artworks, is not controlled by any industry standard,” they said, adding: “Artists are perfectly entitled to be (and often are) inconsistent in their dating of works.”

That approach, however, appears at odds with widespread norms in the art world. Jon Sharples, a respected art and intellectual property lawyer, said that Hirst’s works were bought and sold in a market that took origin and provenance extremely seriously.

“When only one date is mentioned in an artwork title, the convention is, and what I think most people would take that to mean, is that it was first physically made in that year,” he said. In that context, he recommends sellers and artists to “err on the side of transparency” when it comes to dating their works.

Baring, who is director of the Ingram Collection of Modern British and Contemporary Art, agreed about the convention. “There is definitely best practice, which is to give the date of physical creation of a work, or if there is a wide difference between conception and creation, to give both dates,” she said.

It is not known what information the Fertitta brothers received about the origins of the shark sculpture when they bought it. The brothers, who sold the mixed martial arts promotion company the Ultimate Fighting Championship for $4bn in 2016, declined to comment. So too did the Palms resort, which is now under different owners.

In 2018, the Palms’ then general manager gave an interview to the LA Times in which he hinted the brothers had paid a similar amount for the shark as the US hedge fund billionaire Steve Cohen paid for a comparable tiger shark in 2004. Estimates vary for the cost of that piece, The Physical Impossibility of Death in the Mind of Someone Living (1991), a slightly larger tiger shark. However it reportedly cost Cohen between $8m and $12m.

Whatever the Fertitta brothers paid for their Hirst shark, it augmented their already substantial collection of the artist’s work, which they had been building for years. After purchasing the Palms casino and hotel in 2016, they set about filling it with contemporary art by Hirst and others. The hotel still boasts a luxury suite designed by Hirst, which costs $75,000 a night.

But it was the shark that was the crowning glory of their $620m renovation of the Palms complex. It was brought in under cover of darkness, installed in secret, and the unveiling of the sculpture in May 2018 captured the attention of the US press.

In press materials distributed to news media and magazines, the Palms casino announced the official title of the work, along with its “1999” date. The same date was used in licensed photographs of the sculpture and sponsored content paid for by the casino that described the piece as “an important work from the artist’s Natural History series”.

The Fertitta brothers sold the Palms casino in December 2021 to the San Manuel Band of Mission Indians. One source at the resort said the shark sculpture would remain on loan to the venue until at least 2025.

Hirst has rarely made public remarks about the work, although he has occasionally posted about it on his Instagram account. He did so, for example, in May 2018, shortly after the shark was installed, and just a few months after it is now known to have been made at his workshop in Dudbridge, Gloucestershire.

“I’ve known Frank and Lorenzo for years so when they asked me if they could put my shark sculpture from their collection – ‘The Unknown (Explored, Explained, Exploded)’ – in the bar @palms I thought it sounded great,” he wrote.

In a more recent Instagram post, from September 2022, Hirst published three photos of himself bedecked in gold jewellery posing in front of the sculpture, which by then was five years old. In one, he is winking.

“If you’re near Vegas pop into my unknown bar at the @palms casino and have a drink!” he wrote. “Thanks to everyone at the Palms for keeping my art looking so good!!”

Additional reporting by Dan Hernandez in Las Vegas