In 1990, field researcher Sue Hendrickson noticed bones exposed on a slope in South Dakota. The team from the Black Hills Institute had been working in the area and was preparing to leave. Hendrickson continued surveying nearby ground and recognised that the bones could belong to a large animal. Excavation revealed a remarkable Tyrannosaurus rex skeleton, later named SUE after its discoverer.
The find became famous because it preserved far more of one T. rex than is usual, and because its later legal and ownership disputes drew wide public attention. But the specimen's scientific value rests on the bones and their documentation, not on the story alone. The steps from exposed bone to protected jacket are part of the wider work of finding and excavating fossils.
Evidence guide: what SUE's skeleton records
The preserved bones directly document parts of the animal's anatomy, proportions and healed or damaged areas. Comparisons with other tyrannosaurs help interpret growth and function. The specimen does not preserve every soft tissue or moment of behaviour, and a museum mount may use casts or supports. Its completeness is an estimate based on recovered skeletal elements, not a claim that every bone of the living animal is present.
A field survey in South Dakota
Hendrickson was working with the Black Hills Institute team in the summer of 1990. As the crew finished work at the site, she explored a nearby slope. Pieces of bone protruded from the sediment. Their size and shape suggested a large vertebrate, and further inspection showed that the exposure was part of a much larger skeleton rather than a lone fragment.
The initial recognition was a field observation; the identification as Tyrannosaurus rex was established through excavation and anatomical study. This distinction matters. Paleontologists may identify a likely group from visible material, but conclusions become more secure as additional bones are exposed, prepared and compared with known specimens.
Hendrickson's discovery was a key moment, but the excavation was collaborative. Field crews document the quarry, remove rock around the fossil and stabilise fragile bones. Preparators and researchers then continue the work in the laboratory. Naming the discoverer should not obscure the contributions of the team that recovered and studied the skeleton.
Why the SUE specimen is unusual
The skeleton is among the most complete known T. rex specimens. The Russian source estimates roughly 85–90 percent completeness; such figures depend on how completeness is counted, since isolated fragments, paired elements and missing small bones can be treated differently. The important point is comparative: SUE preserves a large amount of associated skeletal material from one individual.
The recovered material includes a substantial skull, vertebrae, ribs, limbs and tail elements. Together these bones allow researchers to measure body proportions and compare the animal with other tyrannosaurs. The skull gives information about the structure of the jaws and head; limb bones can be measured and modelled to investigate support and movement. The skeleton also preserves damage and healing that have been examined as evidence about the animal's life history.
Measurements and biomechanical models are still interpretations built from bones. They can test possible ranges for body mass or movement, but no single model reproduces every action of the living animal. Other T. rex specimens provide important comparisons, and differences among individuals should not automatically be treated as differences between species.
From excavation to the Field Museum
Once uncovered, the fossils had to be stabilised, jacketed, transported and prepared. These steps protect the specimen and make careful study possible. The skeleton later became the subject of a legal dispute over ownership. In 1997, it was sold at auction and acquired by Chicago's Field Museum, where it is catalogued as FMNH PR 2081 and displayed under the name SUE.
The ownership case and auction made the specimen a public story, but they are separate from the biological evidence. A court decision can determine who may hold or sell a fossil; it does not determine what anatomical features mean. Museum care gives researchers and visitors continued access to an unusually informative specimen, while the catalogue record preserves its scientific identity.
SUE became a widely recognised museum exhibit and a symbol of paleontology. The display can show visitors the scale and arrangement of a tyrannosaur skeleton. Labels and diagrams are needed to explain which parts are fossil, how missing areas are supported and what scientists infer from the bones. A mounted skeleton is an interpretation made for study or display, not a direct snapshot of the animal in life.
What one celebrated fossil can and cannot tell us
SUE gives researchers a detailed anatomical record for a single Tyrannosaurus rex. It can be compared with other individuals to study variation, injury and growth. It cannot represent every member of the species, reveal all aspects of its colour or behaviour, or explain the entire ecosystem in which it lived. Those questions require other fossils, geological context and independent lines of evidence.
The discovery also illustrates how paleontology depends on patient observation. Hendrickson's survey brought the bones to attention; the field team's work and later preparation turned the exposure into a research specimen. The fame of SUE makes that chain visible, but the same careful documentation matters for fossils that never become famous.
Frequently asked questions
When did Sue Hendrickson find SUE?
She discovered the exposed bones in 1990 during fieldwork in South Dakota with the Black Hills Institute team.
Where is the SUE Tyrannosaurus rex now?
The specimen, catalogued as FMNH PR 2081, is held and displayed by the Field Museum in Chicago.
How complete is the SUE skeleton?
It is exceptionally complete for a T. rex. The source gives an estimate of about 85–90 percent, though percentages depend on how recovered elements are counted.
Did Sue Hendrickson excavate the whole skeleton alone?
No. Hendrickson recognised the exposed bones, while a field team carried out the excavation and specialists later prepared and studied the fossil.