Earth Science: The Discovery of T-Rex Remains Throughout North America

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Category: Earth, Air, Space Science

Published on Friday, 27 June 2025 11:33

Written by Science Editor

In the summer of 1990, paleontologist Susan Hendrickson made a groundbreaking discovery in the rugged terrain of South Dakota. While exploring the Cheyenne River Indian Reservation, she stumbled upon a set of fossilized bones protruding from a cliff.

These bones belonged to what would later be identified as one of the most complete and well-preserved Tyrannosaurus rex skeletons ever found. This extraordinary discovery was named "Sue," in honor of Hendrickson.

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The skeleton of Sue, at over 40 feet long and 13 feet tall at the hips, is a marvel of prehistoric life. She is estimated to have lived approximately 67 million years ago during the Late Cretaceous period. Sue's discovery provided scientists with invaluable insights into the physiology, behavior, and ecology of Tyrannosaurus rex, one of the most iconic and formidable predators in Earth's history.

The Legal and Ownership Controversy

Although the discovery of Sue was a scientific triumph, it soon became the center of a complex and highly publicized legal battle that left a deep imprint on the field of paleontology. After Sue's excavation by members of the Black Hills Institute, it was initially believed that the fossil belonged to Maurice Williams, the landowner of the site where Sue was found.

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However, a tangled web of claims ensued involving Williams, the Black Hills Institute, the U.S. government, and the Cheyenne River Sioux Tribe. The U.S. federal government claimed ownership of the fossil, arguing that the land where Sue was discovered was held in trust by the government for Williams, and thus the bones could not be sold without federal permission. The legal dispute culminated in a court ruling that awarded ownership of Sue to Williams.

In 1997, Sue was put up for auction at Sotheby's, where the Field Museum of Natural History in Chicago acquired her for a record-breaking $8.36 million. This marked the highest price ever paid for a fossil at the time. Sue now resides at the Field Museum, where she is one of its most popular exhibits, drawing millions of visitors and continuing to inspire paleontological research.

T-Rex Sue. Image credit Janet Walker.

Locations of Other T-Rex Fossil Discoveries

The Tyrannosaurus rex is a species native to what is now North America, and its fossils have been predominantly found in the western regions of the continent. These fossils provide a window into the prehistoric ecosystems of the Late Cretaceous period.

Montana

Montana is a treasure trove for T-Rex fossil discoveries. The Hell Creek Formation, spanning parts of Montana, North Dakota, and South Dakota, is one of the richest sources of T-Rex remains. "Stan," another famous T-Rex skeleton, was discovered in the Hell Creek Formation near Buffalo, South Dakota, but many of the subsequent T-Rex finds in this area also extend into Montana's portion of the formation.

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South Dakota

South Dakota, as the discovery site of Sue, has been a significant region for T-Rex fossils. The Hell Creek Formation here has yielded numerous specimens, making it a hotspot for paleontologists.

Wyoming

Wyoming is another area rich in T-Rex fossils. The Lance Formation, which runs through Wyoming and is geologically similar to the Hell Creek Formation, has provided several important specimens, including well-preserved skulls and skeletal fragments.

Utah

Although less common than in Montana and South Dakota, T-Rex fossils have also been found in Utah. The fossils here add to the evidence that Tyrannosaurus rex had a wide range across prehistoric North America.

Canada

In addition to the United States, parts of Canada, specifically Alberta and Saskatchewan, have yielded Tyrannosaurus rex fossils. The Dinosaur Provincial Park in Alberta is a renowned site for Cretaceous-era discoveries, although it is more famous for yielding other dinosaur species.

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The Scientific Significance of T-Rex Fossils

Every T-Rex fossil discovery adds to our understanding of this apex predator. These fossils provide clues about T-Rex's physical structure, feeding habits, growth patterns, and even its interactions with its environment and other species. For instance, the study of Sue's skeleton revealed evidence of healed injuries, suggesting that T-Rexes engaged in violent encounters, possibly with other T-Rexes.

Furthermore, the study of bone growth rings in T-Rex fossils has helped scientists estimate their lifespan, growth rates, and maturity stages. These insights have not only enhanced scientific knowledge but have also fueled public fascination with this prehistoric giant.

Conclusion

The story of T-Rex Sue is as much about the marvels of paleontology as it is about the complexities of legal ownership and cultural heritage. While Sue's discovery and subsequent controversy highlight the challenges of fossil collection and ownership, they also underscore the profound impact of such finds on science and society.

The continued discovery of T-Rex fossils across North America, from the Hell Creek Formation in Montana and South Dakota to the Lance Formation in Wyoming and beyond, ensures that this legendary dinosaur will remain a subject of fascination and study for generations to come. These fossils serve as enduring reminders of a lost world, offering a glimpse into the life and times of one of history's most formidable predators.