Full Breakdown
Discovery of a Giant Tyrannosaur in North America
3/13/2026, 11:20:11 AM
Ancient Origins of the Hunter Wash Tyrannosaur
A recent analysis of a large shinbone discovered in the Kirtland Formation of New Mexico has revealed that it belongs to a previously unrecognized giant tyrannosaur, potentially a close relative of Tyrannosaurus rex. This fossil, dating back approximately 74 million years to the Late Campanian period, is notable for its size, measuring about 3.2 feet (96 cm) long and 5 inches (13 cm) wide. Researchers estimate that this dinosaur weighed around 4,700 kilograms (10,400 pounds), making it the largest known tyrannosaur from this era.
Implications for Tyrannosaur Evolution
The discovery of the Hunter Wash tyrannosaur supports the hypothesis that the lineage of T. rex may have originated in southern North America, rather than migrating from Asia. Paleontologist Nicholas Longrich from the University of Bath and his team suggest that this find indicates that large tyrannosaurs were evolving much earlier than previously believed. The shinbone's dimensions are approximately 84% of the size of the tibia belonging to Sue, the largest known T. rex specimen, which has been pivotal in understanding tyrannosaur evolution.
Characteristics and Comparisons
The shinbone exhibits traits similar to those of T. rex, including a robust structure and a broad, triangular shape at the foot end. These characteristics differentiate it from Bistahieversor, another known tyrannosaurid found in the same geological layer, which was significantly smaller. The researchers propose that the Hunter Wash tyrannosaur may represent an early member of the Tyrannosaurini group, which includes T. rex and its closest relatives.
Official Statements & Responses
Longrich emphasized the significance of the find, stating, "This kind of tracks... T. rex's enormous size is a specialization that emerges relatively late in tyrannosaur evolution." Co-author Anthony Fiorillo noted, "Given the remarkable similarity of the tibia in our study to that of Tyrannosaurus rex, yes, we feel they are very closely related." The researchers call for further excavation in the Kirtland Formation to uncover more fossils that could clarify the evolutionary relationships of this giant tyrannosaur.
Criticism & Opposition
While the findings are compelling, some paleontologists caution against jumping to conclusions regarding the dinosaur's classification. The current evidence is based solely on a single bone, which limits the ability to definitively assign a scientific name or establish its exact position on the family tree. The need for additional fossils, particularly teeth or more complete skeletal remains, is critical for a more comprehensive understanding of this dinosaur's lineage.
What's Next
Future excavations in the Kirtland Formation are planned to search for more material that could provide insights into the Hunter Wash tyrannosaur's classification and its relationship to T. rex. The ongoing research aims to settle the debate about the origins of the Tyrannosaurus lineage and its evolutionary history in North America.
