The towering Tyrannosaurus rex that greets visitors at The Field Museum is hard to miss. But how well do you really know SUE? To celebrate SUE’s Unearth Day on August 12, the date she was discovered, we’re brushing up on some essential facts:
Who is SUE?
Even though we refer to SUE as a “she,” it is unknown whether this T. rex was female or male. We know that this carnivorous dinosaur lived about 67 million years ago and probably weighed nine tons during its life.
Largest, most complete, and best preserved T. rex
At 40.5 feet long and 13 feet tall at the hip, SUE is physically the largest example of Tyrannosaurus rex out of the more than 30 less complete T. rex skeletons that have been discovered to date.
SUE is also the most complete T. rex skeleton by bone volume, at 90 percent complete. Scientists found some rare bones as part of SUE’s skeleton: the furcula (wishbone), stapes (an ear bone), and almost all the gastralia (belly ribs).
SUE’s fossilized bones are extremely well-preserved. They reveal a high level of both surface and histological (tissue) detail, showing where muscles, tendons, and ligaments were attached to bones. Cross-sections of the bones show that even the cellular structure inside remains intact.
We can learn a lot from studying SUE’s fossilized bones. Dinosaur bones contain rings, much like the rings in a tree stump, that can be counted to determine age. SUE was 28 when she died, making her the most geriatric Tyrannosaurus yet found. Her bones show signs of wear and even disease, including arthritis.
The skull that you see on SUE’s skeleton in Stanley Field Hall is a “corrected cast,” an educated guess as to what her skull looked like without its distortions. Her skull is damaged on the left side (you can take a close look at the original skull on the second floor of the Museum). While scientists once thought that the holes dotting SUE’s left jaw bone were bite marks, it’s now believed that the deterioration is a pathology, perhaps caused by a fungal infection or parasite that possibly contributed to SUE’s death.
67 million years ago to today
SUE was discovered in South Dakota in 1990. But the landscape was dramatically different when she lived 67 million years ago, during the Late Cretaceous Period. This region would have been covered with lush forests that thrived in a warm, humid climate. SUE lived along the eastern shore of an inland sea, very different from the dry plains that exist in South Dakota today. Other animals living alongside SUE may have included freshwater fish, turtles, crocodiles, and salamanders.
Today, SUE the specimen continues to give us insight into physical characteristics and life of this prehistoric predator. Learn about just one of the ways we care for and study SUE from the perspective of Collections Manager, Fossil Vertebrates, Bill Simpson.