A link to the past? Scientists discover ancestor of T. rex in New Mexico 

Scientists studying fossils in Albuquerque have discovered an early ancestor of the Tyrannosaurus rex roamed New Mexico more than 74 million years ago, according to a Thursday news release.

Paleontologists have long debated which continent gave rise to the famous T. rex and this latest discovery points to the theory that it may have evolved right here in the North American Southwest.

Previous theories suggested that the T. rex evolved in Asia, specifically Mongolia, where other fossils were found.

The T. rex, in all its popularity, was “the largest terrestrial predator of its time, and perhaps of all time,” according to paleontologist Nick Longrich, a senior lecturer at the University of Bath and lead author on the study.

New Mexico Museum of Natural History & Science Executive Director Anthony Fiorillo and museum paleontologist Spencer Lucas also coauthored the study.

However, Longrich notes that the dinosaurs’ origins aren’t fully understood and scientists are still searching for the missing link between the T. rex and its earlier ancestors.

A fossil discovered decades prior in New Mexico may be part of that puzzle.

That bone, a meter-long tibia, was initially excavated in 1997 in the Bisti/De-Na-Zin Wilderness near the Navajo Nation by NMMNHS researcher Paul Sealey. The bone was originally thought to belong to the Bistahieversor, also known as the Bisti Beast, a 3-ton two-legged predator similar to the T. rex.

However, after reexamining the bone, scientists now believe it to more closely resemble a dinosaur of the Tyrannosaurus genus.

Research found the tibia belonged to a 4- to 5-ton animal and that its shape is a perfect match for a T. rex’s ankle.

Using radiometric dating of the volcanic ash where the bone was found, scientists determined that the dinosaur it belonged to walked the earth 74 to 75 million years ago.

That’s 8 to 9 million years before the T. rex is believed to have existed, meaning that the bone likely belonged to a closely related ancestor.

“New fossils will support this hypothesis or reject it,” Longrich said in a statement Thursday of the ongoing research. “Either way we’ll walk away with a better understanding of how the dinosaurs evolved.”

The fossil is not on public display but is being held in the museum’s extensive collection.

The NMMNHS has been closed since August for renovations but will reopen to the public on Saturday, April 4.  

Gillian Barkhurst is the local government reporter for the Journal. She can be reached at gbarkhurst@abqjournal.com.