A Tyrannosaurus rex skeleton nicknamed Gus sold for US$50.1 million at Sotheby's in New York overnight, the highest price ever paid for a dinosaur fossil at auction. The buyer bid by phone and stayed anonymous.

Seven bidders chased the skeleton for about 10 minutes, sailing past the US$20 million to US$30 million estimate, with auctioneer Phyllis Kao goading the room along the way: "Try a bigger bite. It's a T. rex, after all."

Gus is about 67 million years old, dug from the Hell Creek Formation on a cattle ranch in Harding County, South Dakota, and excavated over three seasons from 2021 to 2023. The specimen has 183 fossil bone elements, about 61 per cent of the skeleton by bone count, and stands roughly 3.8 metres tall and 11.6 metres long, with a 137-centimetre skull, a rare intact wishbone and a complete pelvis. The name honours Gary "Gus" Licking, the rancher on whose land it was found, who died before the sale.

The price beats the US$44.6 million paid in 2024 for the stegosaurus Apex, which hedge fund billionaire Ken Griffin later loaned to the American Museum of Natural History, and roughly US$31.8 million for the T. rex Stan in 2020, which surfaced years later as the centrepiece of a natural history museum in Abu Dhabi.

Sotheby's vice chair Cassandra Hatton called it "a specimen that's been excavated, documented, prepared, and cared for with real excellence".

The scientists who study these animals were less celebratory. The Society of Vertebrate Paleontology's position is that a fossil held outside an accredited collection is out of reach for research. "Our hope is that the new owner recognizes the extraordinary scientific and educational value of Gus the T. rex and that they aim to keep it in the public trust by immediately donating it to an accredited natural history museum," said Kristi Curry Rogers, the society's president-elect.

Apex went on public display within a year of its sale. Stan took three years to resurface. The sale total is now a record; whether Gus ends up somewhere science can reach him is the buyer's call.