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| SUE, the T Rex at the Field Museum, Chicago |
Their fossilized bones are displayed in a private gallery within the Griffin Halls of Evolving Planet at Chicago’s Field Museum—and yes, SUE has their own suite. After 67 million years, it seems only fair.
Despite the familiar name, scientists do not know whether SUE was biologically female or male. I think of SUE as going with the pronouns they/them.
The dinosaur is named for fossil hunter and explorer Sue Hendrickson, who discovered several enormous vertebrae protruding from an eroding bluff near Faith, South Dakota, on August 12, 1990.
Hendrickson was working with the Black Hills Institute of Geological Research when a flat tire gave her time to explore a nearby outcrop. It was possibly the most productive flat tire in palaeontological history. Six people spent 17 days excavating the skeleton.
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| Field Museum of Natural History, Chicago, USA |
Preparing them was no small undertaking: twelve skilled fossil preparators spent approximately 30,000 hours removing rock, cleaning, repairing and stabilizing the fossils.
The work was carried out in preparation laboratories at the Field Museum and Disney’s Animal Kingdom, where visitors could watch the painstaking process through glass.
The preparation team included Field Museum fossil specialists Bill Simpson and Paul Brinkman, along with other museum preparators and volunteers.
Far from simply brushing away a little dust, they used fine hand tools, air scribes, adhesives and an extraordinary amount of patience to free each bone without damaging its surface. Altogether, the preparation required the equivalent of about twelve person-years of work.
Another 20,000 hours went into studying, casting, mounting and constructing the original exhibition. It was a true labour of love.
About 250 of the estimated 380 bones in a T. rex skeleton are represented, making SUE about 90 percent complete by bone volume. The mounted skeleton contains mostly genuine fossil bone, while specially coloured replicas fill some gaps.
SUE’s immense original skull—too heavy and scientifically valuable to place safely on the neck—is exhibited separately at eye level. A lighter cast sits on the mounted skeleton that you see in the photo here.
SUE provides an unusually complete look at the anatomy of an adult Tyrannosaurus rex. Detailed study and CT scanning of the skeleton and skull have helped researchers examine the construction of the jaws, braincase, vertebral column, limbs and sensory systems.
SUE also preserves a furcula, or wishbone, adding to the extensive anatomical evidence linking theropod dinosaurs with birds. The beautifully preserved gastralia—rib-like bones positioned beneath the ordinary ribs—show that T. rex possessed a deep, muscular belly rather than the fashionably shrink-wrapped waist once given to dinosaurs in older reconstructions. These bones may also have helped move air through the respiratory system.
SUE represents the highly specialized endpoint of a much longer tyrannosaur evolutionary story. The earliest tyrannosauroids were relatively small, lightly built hunters.
Over tens of millions of years, members of the group developed increasingly powerful senses, reinforced skulls, deep jaws and bone-crushing bites. Fossils such as the horse-sized Timurlengia euotica, which lived about 90 million years ago, indicate that sophisticated brains and sharp sensory abilities evolved before tyrannosaurs became gigantic.
Later tyrannosaurids shifted much of the business of catching and processing prey to the head, while the forelimbs became shorter and the body grew truly colossal.
SUE shows us the result of that transformation: a huge, powerfully balanced predator with a massive skull, robust hind limbs and a long tail acting as a counterweight. This was not simply an oversized version of an earlier meat-eating dinosaur.
Tyrannosaurus rex was an evolutionary specialist, built around an exceptionally strong bite, keen senses and the ability to dominate the final Late Cretaceous ecosystems of western North America.
The skeleton also preserves the history of one remarkably battered life. SUE suffered injuries and disease, including healed ribs, damaged vertebrae, arthritis and holes in the lower jaw associated with infection.
Bone growth records indicate that SUE experienced a dramatic adolescent growth spurt, reached adult size at approximately 19 years of age and lived to around 28—an elderly individual by known T. rex standards.
At one point during the teenage years, SUE may have gained roughly two kilograms, or 4.5 pounds, every day. That is what happens when adolescence involves fewer awkward school photographs and considerably more meat.
One skeleton cannot explain the entire evolution of Tyrannosaurus rex, but SUE provides an essential anatomical benchmark against which less complete specimens can be compared. Their nearly complete body helps palaeontologists distinguish evolutionary features shared by the species from injuries, individual variation and changes produced during growth.
SUE is therefore much more than an impressive museum mount. This extraordinary fossil records the evolutionary culmination of the tyrannosaur lineage, the rapid growth of a gigantic predator and the bruising reality of life near the end of the Age of Dinosaurs.
And after surviving infections, injuries, 67 million years underground and 30,000 hours of fossil preparation, SUE still looks remarkably pleased with themselves.
Lead Image: Asset ID: 2569246875. SUE at the Field Museum of Natural History, Chicago, Illinois, USA
