Something to roar about: Researchers uncover another Tyrannosaurus species in New Mexico

Hello world!

Meet Tyrannosaurus rex’s cousin and subspecies — Tyrannosaurus mcraeensis.

According to a new study published in Scientific Reports, the newly discovered predator is older and more primitive than its better-known cousin, but just as large.

The team of researchers who authored the study, which was released Thursday, includes Anthony Fiorillo, New Mexico Museum of Natural History & Science executive director.

Hello world! A new Tyrannosaurus species discovered

The study reshapes the understanding of how the T. rex first arrived in what is now North America. Students from San Felipe de Neri School in Old Town Albuquerque were among the first to see and unveil the new species.

It is based on a partial skull found in 1983 in Elephant Butte, currently on display at NMMNHS, which shows that Tyrannosaurus was in North America millions of years before paleontologists previously thought.

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

Alongside Fiorillo, authors on the study include researchers from the University of Bath in the United Kingdom, University of Utah, The George Washington University, Harrisburg University, Penn State Lehigh Valley and the University of Alberta.

Tyrannosaurus rex, perhaps the largest and most dangerous terrestrial predator of all time, suddenly appeared in North America about 66 million years ago.

But with no close relatives in North America, how it arrived and evolved on the continent remains a mystery.

When then-student Sebastian Dalman began a restudy of a horned dinosaur from the same fauna, it forced a broader rethink of the dinosaurs from western New Mexico.

“I started working on this project in 2013 with co-author Steve Jasinski and soon we started to suspect we were onto something new,” Dalman said.

The team was assembled to study the animal, examining the skeleton bone by bone.

In each case, the team found subtle differences between the specimen and the dozens of T. rex skeletons that had been found before. Because T. rex is so well known, it became possible to show the New Mexico tyrannosaur was something new.

“The differences are subtle, but that’s typically the case in closely related species,” said 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.”

The newly discovered Tyrannosaurus mcraeensis was roughly the same size as a T. rex, which measured up to 40 feet long and 12 feet tall.

Like its famous relative, it was a carnivore.

While the new discovery predates T. rex, the paper notes that subtle differences in the jaw bones make it unlikely that it was a direct ancestor. This raises the possibility that there are still more tyrannosaur discoveries to be made.

“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,” said Spencer Lucas, paleontology curator at NMMNHS.

The new discovery expands human understanding of tyrannosaurs in several ways.

First, it suggests that the apex predators lived in what’s now the southern United States at least 72 million years ago, long before the first fossils of T. rex were found in the same region. Tyrannosaurus likely originated in southern North America, then later expanded into much of the western portion of the continent.

The new fossils also suggest that larger, more heavily built and more advanced species evolved in the southern United States, compared with the smaller and more primitive tyrannosaurs that inhabited Montana and Canada.

These fossils were collected on lands administered by the U.S. Bureau of Reclamation.