Studies show that dinosaurs thrived in New Mexico

For decades, many scientists believed that dinosaurs were already declining in number and variety before an asteroid strike sealed their fate 66 million years ago.

However, new research in the journal Science An international team from Baylor University, New Mexico State University, the Smithsonian Institution and others are rewriting this story.

Dinosaurs, it turns out, weren’t going extinct. They were flourishing.

One last flourish in the San Juan Basin

In northwestern New Mexico, rock layers preserve a hidden chapter of Earth’s history. In the Nashobito Member of the Kirland Formation, researchers uncovered evidence of vibrant dinosaur ecosystems that thrived before the asteroid impact.

High-precision dating techniques have revealed that fossils from these rocks are between 66.4 and 66 million years old—placing them within the catastrophic Cretaceous-Pelagene range.

“Nashubito dinosaurs lived at the same time as the famous Hell Creek species in Montana and the Dakotas,” said Daniel Papi, PhD, associate professor of geosciences at Baylor University. “They weren’t in decline. They were vibrant, diverse communities.”

Dinosaurs in their prime

Fossils from New Mexico tell a different story than originally thought. Far from being homogeneous and fragile, the dinosaur community in North America was regionally distinct and thriving. Using ecological and biogeographic analyses, the researchers discovered that dinosaurs in western North America lived in distinct “bioprovinces,” divided not by mountains or rivers but by temperature differences across regions.

“Our new research shows that dinosaurs are not on a path to mass extinction,” said first author Andrew Flynn, Ph.D., assistant professor of geological sciences at New Mexico State University. “They’re doing great, they’re thriving and asteroid impacts knock them out. It’s been contested for a long time that this long-term decline in dinosaur diversity has led to mass extinctions, making them more vulnerable to extinction.”

Life after the impact

Asteroid impacts ended the age of dinosaurs in an instant — but the ecosystems they left behind set the stage for what followed, researchers said. Within 300,000 years of their extinction, mammals began to diversify rapidly, exploring new diets, body sizes, and ecological roles.

The same temperature-driven patterns that shaped dinosaur communities continued into the Paleocene, showing how climate guided the rebound of life after the extinction.

“Surviving mammals still maintained the same northern and southern bioprovinces,” Flynn said. “Mammals in the north and south are very different from each other, which is different from other mass extinctions where it seems to be very similar.”

Why is discovery important today?

This discovery is more than a window into the past. It is a reminder of the resilience and fragility of life on earth. Conducted on public lands managed by the U.S. Bureau of Land Management, the research highlights how carefully preserved landscapes can provide deep insight into how ecosystems respond to sudden global changes.

With a clear understanding of the timeline of the last days of the dinosaurs, the study does not reveal a slowdown in extinction but rather a dramatic end to the story of a diversity boom fueled by cosmic chance.