There are fossils. And then there’s SUE.
Most dinosaur skeletons on display in museums around the world are reconstructions — fragments of real bone surrounded by sculpted replicas, assembled into an approximation of something that once lived. That’s not a criticism. It’s simply the reality of 66-million-year-old evidence. Bones don’t last forever, and most of the time, very little makes it through.
SUE is different. When palaeontologists finished excavating a hillside in South Dakota in 1990, they had recovered approximately 90 per cent of a complete Tyrannosaurus rex skeleton — more than 250 bones, the most complete T. rex ever found. A specimen so intact that researchers are still making discoveries from it more than three decades later.
This summer, SUE: The T. rex Experience is at TELUS Spark Science Centre in Calgary — and what follows is the story worth knowing before you visit.
August 12, 1990. The Black Hills of South Dakota. A palaeontology crew from the Black Hills Institute of Geological Research is working a dig site when one team member, Sue Hendrickson, sets off on her own to explore a nearby cliff face. The rest of the crew is fixing a flat tire. She finds three massive vertebrae eroding out of the rock, about eight feet above the ground.
She walks back to camp and tells the crew: she’s found a T. rex, and it’s big.
She was right. The skeleton that would eventually bear her name turned out to be one of the most significant palaeontological discoveries of the twentieth century. As Encyclopedia Britannica documents, SUE measures 12.8 metres long and is among the largest known T. rex skeletons ever found.
“Fog finally lifted. Hours later, we reached the butte. It wasn’t long before I saw three articulated vertebrae exposed in the cliff.”
— Sue Hendrickson. Source: Chicago Sun-Times, 2024
Getting SUE out of the ground took a six-person crew 17 days. What followed was a five-year legal dispute over ownership — involving the Black Hills Institute, the US federal government, and the Cheyenne River Sioux Tribe, whose trust land the fossil was found on. In October 1997, the Field Museum purchased SUE at Sotheby’s auction for $8,362,500 — the highest price ever paid for a fossil at the time. SUE made her public debut in Chicago on May 17, 2000.
Why 90% Complete Is a Very Big Deal
Here’s the thing about the fossil record: it’s mostly empty.
For an animal to become a fossil, an extraordinarily specific chain of events must occur. The animal must die in the right place. The body must be buried quickly, before it decomposes or gets scattered. Minerals in the surrounding sediment must gradually replace the organic material over thousands of years. And then, millions of years later, erosion must expose the fossil close enough to the surface that someone finds it before it weathers away entirely.
Most of the time, almost none of this happens. Most dinosaur species we know about are identified from fragmentary remains — sometimes from a single bone.
A skeleton that’s 90% complete changes the science entirely. With most of SUE’s bones present, the Field Museum has been able to study:
“There are questions about the biology of dinosaurs — and Tyrannosaurus in particular — that you can only answer with SUE,” said Peter Makovicky, the Field Museum’s former Curator of Paleontology.
The Questions SUE Is Still Answering
After more than thirty years of study, you might expect SUE to be fully understood. But the answers she’s provided keep generating new questions — and new tools keep opening new ways of looking at the same bones.
Take SUE’s jaw. The Field Museum notes that telltale holes in SUE’s lower jaw were once believed to be caused by a parasitic infection — but it’s now more widely thought they resulted from injury.
Then there are the arms. Each arm could lift an estimated 750 pounds — not nothing — but why T. rex arms are so proportionally short has puzzled scientists for decades.
In 2016, SUE’s right forelimb was removed from display and transported to Argonne National Laboratory, where X-rays a million times more powerful than a hospital CT scan mapped the bone’s interior in unprecedented detail.
In 2022, the arm was CT-scanned again at UChicago Medicine to model range of motion and force. “Jokes aside, the proportions of these forelimbs are very strange,” said Field Museum paleontologist Jingmai O’Connor. The question isn’t settled yet.
“One of the big mysteries about T. rex is its tiny forelimbs. We don’t know how it used them. But there could be clues in the fossils.” — Pete Makovicky, Field Museum Curator of Dinosaurs. Source: Argonne National Laboratory, 2016
What to Look For When You Visit
When you’re standing in front of SUE at TELUS Spark, here are a few things worth pausing on:
Wondering if your kid will be impressed? Start here. CTV News captured the first look at SUE’s Calgary arrival, from the size of the T. rex to the excitement of seeing one of the world’s most famous fossils up close.
Science starts with great questions.
Maybe you’re wondering why dinosaurs probably rumbled instead of roared. Or why a predator with tiny arms, giant eyes and a bone-crushing bite still has mysteries scientists are trying to solve.
Come for the dinosaur. Stay for the questions.
Do you have a science question you’d like us to explore?
Leave it in the comments below!