“Sue”: The Most Complete T Rex Skeleton Ever Found

In 1990, paleontologists working in South Dakota discovered the most complete Tyrannosaurus rex skeleton ever found. Scientifically priceless, the fossil skeleton (named “Sue” after the person who found it) became the center of a legal controversy around Native American rights and Federal lands, was seized and confiscated by armed federal agents in a spectacular raid, and was crated up for years before finally being sold at public auction for a record price and ending up on display at the Field Museum in Chicago.


“Sue”, on display at the Field Museum in Chicago.

On August 12, 1990, a group of paleontologists and workers from the Black Hills Institute, a privately-owned company that excavates and sells fossils, was finishing up a summer dig at the Cheyenne River Indian Reservation, near the town of Faith, South Dakota. The dig had been mildly successful, with the discovery of some bones from Edmontosaurus, a species of duck-billed dinosaur, and Triceratops, the familiar three-horned plant-eater.

As the team prepared to leave, their truck got a low tire, and while it was taken to town to be fixed, one of the Institute’s workers, amateur fossil prospector Sue Hendrickson, wandered off to explore a nearby cliff face. As she walked along, she found a few pieces of fossilized bone. Looking up at the cliff face, she saw parts of a vertebral column and several other large bones weathering out, and realized that there was probably a skeleton there. Hendrickson took a few pieces of bone back to the truck, where paleontologist Peter Larson, the president of the Black Hills Institute, identified them as a T rex. When the team examined the cliff face, they were excited to discover more bones extending back into the cliff.

The team quickly extended their expedition time, brought in a new supply of plaster, and began excavating the fossils. In total, about 80 percent of a complete skeleton was found. It was named “Sue” after its discoverer, and remains the most complete T rex ever found. To reach the skeleton, the excavators had to remove 29 feet of rock and soil from the top of the cliff. Then the rock chunks that contained the bones were carefully dug out one by one, wrapped in a protective burlap and plaster jacket to protect them from breakage, and trucked to the Black Hills Institute’s lab in Hill City, South Dakota, where preparators began the long tedious work of carefully “preparing” the fossils by cleaning off all the rock that surrounded them. It had already been decided that Sue would be the centerpiece for the new museum exhibition building that the Institute was planning to build.

But even as the bones were being cleaned, a legal controversy had already begun. The land where the Black Hills Institute found Sue was owned by Maurice Williams, a member of the Lakota Nation who lived on the Cheyenne River Reservation. Williams had granted permission for the Institute to dig there, and when the Sue skeleton was found, an agreement was reached for a payment of $5,000 to Williams. At this point, it was not clear how valuable the complete skeleton actually was–and once the true scientific and commercial value was apparent, the dispute began. The Institute later explained that it had paid the $5,000 for the outright purchase of the fossils; Williams explained that he had only granted the right to remove the skeleton and clean it so it could be sold later. Shortly afterwards, the Lakota Tribe claimed ownership of the skeleton since it had been found on tribal lands–then the Federal Government piped in to claim ownership because those lands were held in trust for the tribe by the Department of the Interior, making the US Government the legal owner. Of all the claimants, the US Government was the biggest and baddest, so in 1992, acting on a court order, FBI agents and armed National Guard troops swarmed into the Black Hills Institute’s lab, seized the entire collection of Sue’s bones, took them to the South Dakota School of Mines and Technology, and held them there until the legal ownership issues were sorted out in court.

The contentious three-year trial centered around issues of the relationship between the Native American Nations and the Federal Government, and also around issues of private for-profit fossil-collecting on public lands. For decades, professional paleontologists had resented the large number of amateur excavators who had been prospecting for fossils on public land, which they dug up and sold at profit to private collectors. To the professionals, the private fossil business was merely a pack of looters, who were exploiting public resources for profit and were removing scientifically-important fossils from the opportunity for public display and scientific study. And in the eyes of many paleontologists, the Black Hills Institute was one of the primary offenders. The Institute countered that most of its sales were to public museums, and that private collectors performed a valuable service by finding and excavating fossils that would otherwise go uncollected, left to erode away without ever being studied.

But the real legal issue at hand centered around land on Indian reservations, and who owned it. Since the 1890’s, Native American Nations in the US have been viewed, legally, as “wards of the government”–a strange sort of quasi-independence in which the native tribes were legally sovereign and independent nations, but also at the same time were considered too backwards to make their own decisions, and were therefore under the “care” of the Federal government, which held all their land in “trust” to manage on their behalf, for their own good. The Sue T. rex trial, which resulted when the Black Hills Institute sued in Federal Court to have the skeleton returned to it, brought all these issues to the forefront, as Maurice Williams claimed ownership of Sue as the individual landowner, the Black Hills Institute claimed it had purchased the ownership rights to Sue, the Lakota Nation claimed ownership under tribal sovereignty, and the US Government claimed ownership under its legal trust of Native lands.

In 1995, after years of contentious arguments, the Federal court, in a long complicated decision, finally ruled that although the US Government held the land in trust, Maurice Williams, as the deeded owner of the land where the skeleton was found, was Sue’s legal owner. Because the land was held in trust for him by the US Government, the Court ruled, Williams could not legally sell the land or anything on it (including Sue) to anyone else (such as the Black Hills Institute) without prior permission from the US Department of the Interior, and therefore the Institute had no ownership claim on the fossil.

After the ruling, Williams contacted Sotheby’s in New York to arrange an auction for the skeleton. This, in turn, presented the probability that the Sue skeleton would be purchased by some wealthy private owner and might never be available for public display or scientific study. To prevent that from happening, the Field Museum in Chicago decided to bid for the fossil, and arranged agreements with a number of public and private sponsors, including McDonalds, the Walt Disney Company, and the California public university system, to pledge money towards the purchase price. On October 4, 1997, Sotheby’s auctioned off Sue. The bidding began at half a million dollars, lasted ten minutes, and ended when the Field Museum submitted a winning bid of $7.6 million (adding Sotheby’s commission brought the total price to $8.36 million)–the highest price ever paid for a fossil.

The Field Museum spent the next few years finishing the preparation work that had already been begun by the Black Hills Institute. McDonald’s Corporation funded the construction of two new prep labs–one inside the Field Museum itself, and the other at Disney World’s new Animal Kingdom park. In both places, the preparators would work in glass-walled rooms where they could be observed by the public. Pieces of Sue were sent, one at a time, to be cleaned and prepped, and for copies to be cast. One complete set of casts was kept at the Field Museum for use by scientific researchers. Another was assembled into a skeleton and placed on display at Disney World. Two other complete skeleton casts were sent on a travelling exhibit sponsored by McDonald’s. And the original bones were assembled into a complete skeleton and placed on display at the Field Museum’s Rotunda (well, almost a complete skeleton–Sue’s skull was too heavy to be mounted, so a plastic cast was mounted on her skeleton, and the original skull was displayed separately in an enclosed glass case).

Sue’s skeleton proved to be a scientific bonanza. Before assembly, each individual bone was extensively photographed. Individual bones of interest were also CAT-scanned so the internal structure could be studied.  The skull was too large to fit any hospital CAT scanner, so it was shipped to a Boeing plant in California to be CAT-scanned with equipment that was normally used to scan parts for the Space Shuttle.

Study of the bones revealed that Sue was 28 years old when she died, measured about 42 feet from nose to tail, 12 feet high at the hips, and probably weighed about eight tons. Her skull alone was about five feet long. She had lived near the end of the Cretaceous period, about 65 million years ago, not long before the dinosaurs went extinct. She had died in a river bed, not far from the vast shallow sea that once covered most of the Great Plains. Her body had been quickly buried, perhaps by a flood, which prevented scavengers from dismembering her skeleton and allowed her bones to be fossilized over time.

Sue had a hard life. Several ribs on both sides of her body had been broken and healed. The bones in her left foot showed abnormal growths from a deep infection, and her right shoulder showed signs of bone and tendon damage. Her jaw contained a number of holes that were originally thought to be toothmarks from another T rex, but were ultimately found to be the result of infections from parasites. Her tail contained signs of arthritis in the vertebral joints. None of these injuries were fatal, and it remains unknown how Sue ultimately died.

A small number of other dinosaur bones were also found with Sue. The Edmontosaurus bones found near Sue’s rib cage were acid-etched, and are likely stomach-contents, the remains of Sue’s last meal. And isolated bones from a juvenile and a young adult T rex were also found with Sue. It is not known how they got there or what relationship they may have had to Sue.

Sue’s skeleton went on exhibit at the Field Museum in May 2000. Over 10,000 visitors swarmed the Museum on the first day, and Sue has been the most well-known exhibit at the Field Museum ever since.


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