Nanotyrannus Skeleton Once Mistaken for Young T. rex Heads to Auction in New York

A mounted dinosaur skeleton once thought to be a juvenile Tyrannosaurus rex is going under the hammer at Sotheby's in New York on Tuesday, with a starting price of at least $6m (£4.5m). The auction house expects it to fetch as much as $9m.

Nicknamed "Jodi", the roughly 10-foot-tall (3m) skeleton belongs to Nanotyrannus, a Late Cretaceous carnivore. Sotheby's calls it an "excellent exhibition-ready" specimen with about 191 fossil-bone elements and a "beautifully preserved, virtually complete skull". The auction house says it is one of only three such skeletons known to science.

The sale arrives a year after US researchers confirmed that Nanotyrannus is a distinct genus, and Sotheby's says Jodi is the first such skeleton to reach the market since then. When the skeleton was displayed at London's Frieze Masters art fair in October 2023, it was presented as a juvenile T. rex, before the genus had been classified.

The skeleton was found in Montana by rancher Jodi Pierson on her land in the Hall Creek Formation, a heavily studied geological site. Commercial palaeontologist Clayton Phipps later excavated it. Phipps also found the well-known "Dueling Dinosaurs" fossil in 2006, about eight miles (13km) away. That specimen, which appears to show a Nanotyrannus and a Triceratops in combat, was central to the research by Lindsay Zanno and James Napoli that ended decades of debate over whether the two predators were separate animals.

Megan Jenkins, a palaeontologist at the University of Portsmouth, told BBC Radio 4's Today programme that Nanotyrannus "was for a very long time believed to be sort of a teenager of T. rex". In fact, she said, it is much smaller and more gracile, "very sort-of sleek, slender" with blade-like teeth for slicing meat. The two dinosaurs lived alongside each other about 67 million years ago.

The auction follows Sotheby's sale of a T. rex called "Gus" in July for a record $50.1m (£37.4m). Some scientists fear such sales could mark a new era of fossil collecting by the ultra-rich, and researchers told the BBC after that sale that remains should be shown in public spaces where they can be studied more freely.

Prof Steve Brusatte of the University of Edinburgh, a consultant on the Jurassic Park films, called the July auction "concerning" and said he knew of no museum or university that could afford such a price. He compared it to the Mona Lisa being owned by a super-wealthy person and kept from public view. Responding to the Jodi sale, he called it "harrowing" that the skeleton could vanish into a collector's vault rather than inspire families and children in a museum.

Jenkins offered a different view, saying there are two sides to the debate and that excavating such specimens takes a great deal of time, effort and money. "I don't begrudge the people involved for wanting to sell it for such a large amount of money," she said. Although the prospect is "scary", she noted that many such fossils have ended up in the public eye, and she believes these specimens will "without a doubt" end up in a museum at some point.