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New dinosaur species,  Tyrannosaurus mcraeensis, discovered in New Mexico

A giant discovery has revolutionized our understanding of the Tyrannosaurus rex‘s origins in North America. This research introduces Tyrannosaurus mcraeensis, the earliest known relative of the iconic T. rex on the continent.

This newly unearthed predator shares a striking resemblance in size with the infamous T. rex, akin to a double-decker bus.

How Tyrannosaurus mcraeensis was discovered

The catalyst for this discovery was a partial skull, unearthed years ago in western New Mexico and displayed at the New Mexico Museum of Natural History & Science (NMMNHS).

This specimen suggests that the Tyrannosaurus species inhabited North America much earlier than previously believed.

An illustrious team of researchers from various esteemed institutions, including the University of Bath (UK), University of Utah, The George Washington University, Harrisburg University, Penn State Lehigh Valley, University of Alberta, and the NMMNHS, contributed to this study.

“New Mexicans have always known our state is special, now we know that New Mexico has been a special place for tens of millions of years,” Dr Fiorillo, Executive Director of NMMNHS said.

“This study delivers on the mission of this museum through the science-based investigation of the history of life on our planet.”

T. Rex‘s mysterious origins

The appearance of Tyrannosaurus rex, arguably the largest and most formidable land predator in history, in North America about 66 million years ago was shrouded in mystery, especially due to the absence of close relatives on the continent. This discovery sheds light on this enigma.

The journey to this revelation began when then-student Sebastian Dalman revisited the study of a horned dinosaur from western New Mexico, sparking a comprehensive reevaluation of the region’s dinosaur fossils.

Dalman recalls, “I embarked on this project in 2013 with co-author Steve Jasinski. As we delved deeper, we began suspecting we were uncovering something unprecedented.”

The researchers meticulously examined the skeleton, comparing each bone with those of numerous T. rex specimens. They identified subtle yet significant differences, affirming the uniqueness of the New Mexico tyrannosaur.

“The differences are subtle, but that’s typically the case in closely related species,” said Dr Nick Longrich, a co-author from the Milner Centre for Evolution at the University of Bath.

“Evolution slowly causes mutations to build up over millions of years, causing species to look subtly different over time.”

Ancestral tree of Tyrannosaurus mcraeensis

The Tyrannosaurus mcraeensis, roughly parallel in size to the T. rex, was a formidable meat-eater. The study highlights jawbone distinctions that suggest it’s not a direct T. rex ancestor, hinting at more undiscovered tyrannosaur species.

Dr. Spencer Lucas, Paleontology Curator at NMMNHS, emphasizes this point, saying, “Once again, the extent and scientific importance of New Mexico’s dinosaur fossils becomes clear — many new dinosaurs remain to be discovered in the state, both in the rocks and in museum drawers!”

This discovery expands our knowledge of tyrannosaurs in several aspects. It suggests that apex predators like T. rex roamed the southern United States at least 72 million years ago.

The study theorizes that tyrannosaurs likely originated in southern North America before expanding westward.

Interestingly, the fossils, unearthed on lands managed by the U.S. Bureau of Reclamation, indicate that larger and more advanced tyrannosaurs evolved in the southern United States.

These fossils contrast with the smaller and more rudimentary species in regions like Montana and Canada. This pattern of size evolution in dinosaurs is the opposite of what is observed in modern mammals.

Finally, towards the end of the Cretaceous Period, these giant tyrannosaurs, alongside other large dinosaurs like Triceratops and Torosaurus, spread northward.

This movement might have been driven by the emergence of new food sources capable of sustaining such colossal creatures.

In summary, the discovery of Tyrannosaurus mcraeensis, stemming from the analysis of a partial skull found in western New Mexico, suggests an earlier presence of Tyrannosaurus in North America.

The study’s revelation that Tyrannosaurus likely originated in southern North America highlights the evolutionary patterns of tyrannosaurs, contrasting with those of modern mammals and adding a new chapter to our understanding of these prehistoric giants.

Over a century after the first discovery of Tyrannosaurus, these findings remind us that there’s still much to learn about these prehistoric giants.

More about Tyrannosaurus rex

As discussed above, Tyrannosaurus rex, often abbreviated as T. rex, stands as one of the most renowned dinosaurs in the prehistoric world.

This colossal predator roamed the earth about 68 to 66 million years ago, during the late Cretaceous Period.

Size and diet

Characterized by its massive size, the T. rex measured up to 40 feet in length and could reach a height of 12 feet at the hips.

Its most striking features included a large, heavy skull balanced by a long, heavy tail, and its tiny, almost comical forelimbs which contrasted sharply with its otherwise formidable appearance.

Despite their size, these arms were incredibly strong, capable of lifting hundreds of pounds.

The T. rex was a carnivorous dinosaur, and its diet consisted primarily of other large dinosaurs. It had an extraordinary biting force, one of the strongest ever recorded for any terrestrial animal.

Its jaws were filled with large, serrated teeth that could grow up to 12 inches long, perfect for tearing into flesh and bone.


Recent studies have shed light on the T. rex‘s sensory abilities. Its keen sense of smell, for instance, was likely among the best in the dinosaur kingdom, enabling it to track prey over great distances.

Moreover, there is growing evidence that suggests the T. rex may have been more than just a solitary hunter, possibly displaying complex social behaviors such as hunting in packs and caring for its young.

The T. rex‘s legacy continues to captivate scientists and the public alike. Not only does it play a starring role in pop culture and media, but ongoing research into its biology and ecology keeps providing new insights into this iconic dinosaur.

The T. rex, a true titan of the prehistoric era, remains a symbol of the awe-inspiring world of dinosaurs.

The full study was published in the journal Nature.


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