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

Exclusive: Sculpture bought by US billionaires was made almost 20 years after date that appears in its name

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.