Sue the T. rex: The Skull in Chicago, the Find and the Sale

The story starts on August 12, 1990, near the small town of Faith, South Dakota. Sue Hendrickson, working on a commercial fossil dig run by the Black Hills Institute, spotted vertebrae weathering out of an eroded bluff. According to the Field Museum, six people then spent 17 days extracting the skeleton from the rock.

The bluff stood on the ranch of Maurice Williams, inside the Cheyenne River Sioux Reservation. That detail, which might sound like a footnote, turned into the whole second act. The dinosaur that came out of the ground shares its name with the woman who spotted it, and it was about to land at the center of a long court fight.

The Black Hills Institute excavated and prepared the fossil after paying Williams $5,000, a payment the Institute said had bought the skeleton. Federal authorities did not see it that way. In May 1992 they seized Sue, according to the National Park Service.

The question went to the federal appeals court for the Eighth Circuit. In December 1993 the court held that the United States held the fossil in trust for Williams. His land was held in federal trust, and he had not obtained the Department of the Interior approval that a sale from that land required, so the $5,000 deal could not transfer ownership. A later 1996 ruling rejected the Institute's claim to a $209,000 lien for its excavation work.

So, by the time Sue went to auction, the legal owner was Maurice Williams, with the United States holding title in trust for him. This is history, not legal guidance on fossils; who owns a find depends on the land, the country and the laws that apply there.

Sotheby's put Sue up for sale in New York on October 4, 1997. The Washington Post reported the next day that the winning bid came in at $7.6 million, and that with the buyer's premium the Field Museum paid $8,362,500. The museum bought Sue for public display in Chicago, which is where the skeleton has stood ever since. The mounted skeleton went on show in 2000.

Sue's skull is about five feet long and weighs about 600 pounds. The Field Museum explains that the mounted skeleton therefore carries a lighter cast of the skull, while the real one is displayed on its own. That arrangement does two jobs. It spares the mount from holding up a head that heavy, and it puts the original fossil at eye level, in a case where scientists can get to it more easily.

There is another reason the cast on the skeleton looks a little tidier than the real thing. The original skull is distorted and damaged on its left side, and the skull on the mount is a corrected cast. When people ask whether the skull on the skeleton is real, that is the answer: the head on the body is a cast, and the real one is the battered, heavy fossil in the case nearby.

Sue moved into a new gallery at the Field Museum, the Griffin Halls of Evolving Planet, in 2018.

Look closely at the back half of the left lower jaw and you will see several holes, some about the diameter of a golf ball. An earlier explanation pointed to infection. In 2022, a peer-reviewed study in Cretaceous Research by Bruce Rothschild, Jingmai O'Connor and María Cecilia Lozada examined the holes and saw signs that the bone had healed, but no evidence that a protozoan parasite infection caused them.

That still leaves the question open, and the scientists do not agree on the answer. As the Field Museum reported, Rothschild favored wounds from bites or claws, while O'Connor considered that explanation unconvincing. What can be said is that the bone shows healing and the exact cause is still unresolved. So, if you have heard that the holes came from a fight, that is one scientist's leading idea, not a settled fact.

The Field Museum describes Sue as 40.5 feet long and 13 feet tall at the hip. The skeleton is about 90 percent complete by bone volume, with about 250 of the roughly 380 bones in a T. rex skeleton, as the museum's page on which dinosaur bones are real explains. Some of those bones are rarely preserved at all: Sue has a furcula, or wishbone, a stapes, the tiny bone of the ear, and almost all of the gastralia, the belly ribs.

Age is a little harder to pin down, because it depends on who is counting and how. The Field Museum's educational page How well do you know SUE? gives 28 years at death, read from growth rings in the bones. A later Field Museum account says about 33 years. A peer-reviewed growth study gives a range of 27 to 33 years, depending on the model the scientists used. However you slice it, Sue was an unusually old adult T. rex.

Sue is on permanent display at the Field Museum, 1400 S. DuSable Lake Shore Drive, Chicago. As of October 2026, the museum's visiting page lists daily hours of 9 a.m. to 5 p.m., with last entry at 4 p.m., and the museum is closed on Thanksgiving and Christmas Day. The Sue gallery is bilingual, with its text in English alongside Spanish, and photography is allowed for personal, non-commercial use. Admission, timed entry and special exhibitions change, so confirm them with the Field Museum before you go.

When you get there, find the skeleton first, then walk over to the case and look at the real skull. The cast tells you what Sue looked like. The fossil, with its crushed left side and its healed holes, tells you what Sue went through.

Most famous fossils are famous for being big. Sue is famous for being big, nearly complete, old, injured, fought over in court and sold for millions, and the skull carries a share of all of it. If you want to see how much a skull leaves out of a living face, the hippo skull makes the point beautifully, and our pieces on what bones tell archaeologists and how old these bones are look at how scientists read age and injury from bone.

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