How to Value Fossils and Other Non

July is generally a quiet month in the auction calendar, but this year, Sotheby’s captured global attention by offering “Gus,” a 67-million-year-old Tyrannosaurus rex in its Natural History auction in New York. Needless to say, it was the first time a dinosaur was exhibited at the Breuer Building, the Modernist landmark built to house the Whitney Museum and now serving as Sotheby’s global headquarters, which made the exhibition of the 12 ½-foot-tall, 38-foot-long fossilized skeleton especially dramatic. Estimated at $20-30 million, Gus went for an incredible $50.1 million.

A T. rex isn’t a traditional sculpture, even when it’s shown in a gallery, and yet it commanded a price that one would expect from a top-tier modern or contemporary artwork at an evening sale. Auction house specialists value artworks based on a combination of factors, like rarity, quality, art-historical importance and provenance. Generally, the most valuable art has extensive documentation, such as exhibition and publication histories, which collectors also use to gauge value. But what are the considerations that go into determining the value of a prehistoric fossil that lay hidden in the ground since the late Cretaceous period?

Provenance is important for an artwork, but it’s the critical factor that affects a dinosaur fossil’s marketability and value. When collectors, museums and auction houses evaluate a dinosaur specimen, one of the first questions they ask is where it was found. The find site determines not only the fossil’s scientific context, but also whether it can be imported, exported, sold or even legally owned. A spectacular specimen with uncertain provenance or a risk of claims from foreign governments can be effectively unsaleable while a lesser fossil with clear title may command a considerable price.

U.S. Protected Lands vs. Private Property

Fossil ownership laws vary dramatically across jurisdictions, so for the market, a specimen’s provenance can be more important than its scientific significance. In the United States, fossils recovered from federal land are generally considered public resources held in trust by the federal government and may not be legally sold. Under the Paleontological Resources Preservation Act of 2009, scientifically significant fossils may only be collected pursuant to a scientific permit and must be deposited in an approved repository, such as a museum or university research collection, where they remain accessible to scientists and the public. Similar protections apply on many state-owned lands, and fossil collecting on Native American lands is governed by tribal authorities. As a result, fossils discovered on federal or otherwise protected lands aren’t typically legally available to private buyers, regardless of their scientific or commercial appeal.

In the United States, different laws apply to privately owned property. Fossils found there generally belong to the landowner and may be lawfully sold, creating the legal foundation for a robust commercial fossil market.

Other countries take a different approach. Many, including Mongolia, Morocco and Brazil, treat dinosaur fossils much the way they treat antiquities. They’re part of the national patrimony, irrespective of whether they’re found on public or private land. They can’t be privately owned and may not be legally exported or traded. And the force of these laws doesn’t stop at a country’s border. In the case of Mongolia, the actor Nicholas Cage discovered this the hard way. In 2007, he acquired the skull of a Tyrannosaurus bataar from a Beverly Hills gallery for $276,000.

In 2014, the Department of Homeland Security (DHS) tracked down the dinosaur and informed Cage that the fossil had been stolen. There was little question it had been: that species has been found only in Mongolia. Cage surrendered his dinosaur skull and wasn’t accused of any wrongdoing.

Because those countries’ laws vest ownership in the State, U.S. law treats fossils taken from those countries as stolen property. The DHS has forced collectors to surrender fossils covered by these laws, and at least one individual has been imprisoned for dealing in them. Therefore, given the legal pitfalls, the next time you want to pick up some dinosaur fossils while on vacation in Marrakech, you may want to call us first!

U.S. law permits a licit market, making the United States the most important source for large, complete dinosaur skeletons. “Gus,” the Tyrannosaurus rex skeleton that Sotheby’s sold in July, is an excellent example. Gus is among the most complete T. rex specimens ever discovered. It has 75% to 80% of the animal’s total skeletal mass. This, combined with its anatomical rarities (including almost complete dinosaur feet and healed battle scars and bites from other dinosaurs) and its impeccable find site on private land, made Gus the ultimate “trophy dinosaur.” The auction house was involved with the dig from the outset, photographing every step, and presented the story in a carefully produced 11-minute documentary video filmed at the dig site. The impeccable provenance combined with the rarity of the dinosaur itself, propelled the record setting price.

Fossils are a special category of objects, but the question of how to assess value is increasingly relevant as a number of non-traditional collectibles are appearing alongside art at the major auction houses. Music and sports memorabilia are also surging in value, with prices often turning on “proof” that a particular object was part of popular history. In March, David Gilmour’s “Black Strat” became the world’s most expensive guitar when it sold at Christie’s for $14.6 million. The auction house documented that the instrument was used on every Pink Floyd album, so its sound was embedded in the consciousness of millions of fans. For sports memorabilia, value hinges on definitively connecting a particular item to a great player and a notable game. Over the summer, Sotheby’s offered a basketball warm-up jacket that had been worn by Wilt Chamberlain in the 1972 NBA finals in its Summer Sports Marquee auction. The jacket was discovered at Goodwill by a 19-year-old treasure hunter for $3.07! The auction house proved its historical significance through rigorous photo-matching against 54-year-old images from the NBA Finals. It ultimately went for $89,600 – nothing close to the $10.1 million Sotheby’s got in 2022 for Michael Jordan’s “Last Dance” game-worn jersey from the 1998 NBA finals, but not bad for a $3 thrift-store find.