Largest Tyrannosaurus Rex | Chicago, Illinois
As the largest and most complete Tyrannosaurus rex skeleton ever found, SUE is a vital fossil specimen to the paleontological community.
Sue is the nickname given to FMNH PR 2081, which is one of the largest, most extensive, and best preserved Tyrannosaurus rex specimens ever found, at over 90 percent recovered by bulk. It was discovered on August 12, 1990, by Sue Hendrickson, an explorer and fossil collector, and was named after her.  After ownership disputes were settled, the fossil was auctioned in October 1997 for US$8.3 million, the highest amount ever paid for a dinosaur fossil until October 7, 2020 when T. rex Stan was auctioned for US$31.8 million. Sue is now a permanent feature at the Field Museum of Natural History in Chicago, Illinois.
During the summer of 1990, a group of workers from the Black Hills Institute, located in Hill City, searched for fossils at the Cheyenne River Indian Reservation in western South Dakota near the city of Faith. By the end of the summer, the group had discovered Edmontosaurus bones and was ready to leave.
However, a flat tire was discovered on their truck before the group could depart on August 12. While the rest of the group went into town to repair the truck, Sue Hendrickson decided to explore the nearby cliffs that the group had not checked. As she was walking along the base of a cliff, she discovered some small pieces of bone.
She looked above her to see where the bones had originated, and observed larger bones protruding from the wall of the cliff. She returned to camp with two small pieces of the bones and reported the discovery to the president of the Black Hills Institute, Peter Larson. He determined that the bones were from a T. rex by their distinctive contour and texture. Later, closer examination of the site showed many visible bones above the ground and some articulated vertebrae.
The crew ordered extra plaster and, although some of the crew had to depart, Hendrickson and a few other workers began to uncover the bones. The group was excited, as it was evident that much of the dinosaur had been preserved. Previously discovered T. rex skeletons were usually missing over half of their bones.
It was later determined that Sue was a record 90 percent complete by bulk, and 73 percent complete counting the elements. Of the 360 known T. rex bones, around 250 have been recovered. Scientists believe that this specimen was covered by water and mud soon after its death, which prevented other animals from carrying away the bones. Additionally, the rushing water mixed the skeleton together.
When the fossil was found, the hip bones were above the skull and the leg bones were intertwined with the ribs. The large size and the excellent condition of the bones were also surprising. The skull was 1,394 mm (54.9 in) long, and most of the teeth were still intact. After the group completed excavating the bones, each block was covered in burlap and coated in plaster, followed by a transfer to the offices of The Black Hills Institute, where they began to clean the bones.
Hendrickson’s discovery was extremely important in helping us better understand dinosaurs. Scientists were able to support the long-standing theory that modern birds evolved from, or are related to, dinosaurs. In addition, the fossil allowed them to learn that the T-Rex was a lot slower than had previously been hypothesized.
Two years after discovering Sue, Hendrickson joined a team of marine archaeologists in 1992 to take part in another series of diving expeditions. Two of her team’s most notable discoveries on this trip were the Royal Quarters of Cleopatra as well as Napoleon Bonaparte’s lost fleet from the Battle of the Nile.