Fossil Discovered in New Mexico May Belong to T. Rex Ancestor

Researchers believe the fossil could provide new insights on the evolution of tyrannosaurs.

Mar. 12, 2026 at 5:50pm

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Scientists have identified a fossil found in New Mexico as belonging to a dinosaur that may have been an ancestor of the Tyrannosaurus Rex. The research suggests large tyrannosaurs lived in New Mexico millions of years earlier than previously thought, potentially shifting the timeline for how some of the largest predators evolved.

Why it matters

This discovery could bring researchers closer to understanding where and how tyrannosaurs, including the iconic T. Rex, evolved. It challenges existing timelines and may provide new insights into the origins of these massive predators.

The details

The fossil was a shin bone found in the Bisti De-Na-Zin wilderness in New Mexico. Researchers initially identified it as Bistahieversor but later matched it more closely with Tyrannosaurus. Radioactive dating places the fossil at 74 to 75 million years old, suggesting a T. Rex ancestor may have roamed the area.

  • The fossil was discovered in the Bisti De-Na-Zin wilderness in New Mexico.
  • Radioactive dating places the fossil at 74 to 75 million years old.

The players

Dr. Anthony Fiorillo

Executive Director of the New Mexico Museum of Natural History and Science.

Dr. Spencer Lucas

Curator at the New Mexico Museum of Natural History and Science.

Dr. Nick Longrich

Lead author of the study published in Scientific Reports.

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What they’re saying

“This New Mexico discovery shifts the timeline for how some of the largest predators of all time evolved and provides new insight on where they came from.”

— Dr. Anthony Fiorillo, Executive Director, New Mexico Museum of Natural History and Science (kob.com)

“Debate is how science proceeds. By throwing this hypothesis out there, it will provoke debate and hopefully encourage people to take a closer look at museum collections and look for new material in the field. New fossils will support this hypothesis or reject it. Either way we'll walk away with a better understanding of how the dinosaurs evolved.”

— Dr. Nick Longrich, Lead Author, Scientific Reports (kob.com)

What’s next

The New Mexico Museum of Natural History and Science will reopen on April 4, potentially allowing further research and exploration of the fossil discovery.

The takeaway

This fossil discovery in New Mexico challenges existing timelines for the evolution of tyrannosaurs and could provide valuable new insights into the origins of these iconic prehistoric predators, highlighting the importance of continued scientific exploration and debate.