New Baylor-Led Research Rewrites the Story of Dinosaur Extinction
Dinosaurs Were Thriving—Until Everything Changed
New Baylor-Led Research Rewrites the Story of Dinosaur Extinction
Artist illustration of an alamosaurus. (Credit: Natalia Jagielska)
For decades, many scientists believed dinosaurs were already dwindling in number and variety long before an asteroid strike sealed their fate 66 million years ago. New research published in Science from Baylor University, New Mexico State University, the Smithsonian Institution, and an international team is rewriting that story.
The dinosaurs, it turns out, were not fading away. They were flourishing.
In northwestern New Mexico, layers of rock preserve a hidden chapter of Earth’s history. Fossils from the Naashoibito Member of the Kirtland Formation reveal vibrant dinosaur ecosystems that existed right up to the catastrophic Cretaceous–Paleogene boundary. Using high-precision dating techniques, researchers determined the fossils are between 66.4 and 66 million years old.
“The Naashoibito dinosaurs lived at the same time as the famous Hell Creek species in Montana and the Dakotas... They were not in decline – these were vibrant, diverse communities.” – Daniel Peppe, Ph.D.
Far from being uniform or weakened, dinosaur communities across North America were regionally distinct and thriving. Ecological and biogeographic analyses revealed that dinosaurs lived in separate “bioprovinces,” divided not by mountains or rivers, but by temperature differences across regions.
“What our new research shows is that dinosaurs are not on their way out going into the mass extinction,” said first author Andrew Flynn, Ph.D., ‘20, assistant professor of geological sciences at New Mexico State University. “They're doing great, they're thriving and that the asteroid impact seems to knock them out. This counters a long-held idea that there was this long-term decline in dinosaur diversity leading up to the mass extinction making them more prone to extinction.”
The asteroid impact ended the age of dinosaurs in an instant—but the ecosystems they left behind shaped what came next. Within 300,000 years, mammals began rapidly diversifying, exploring new diets, body sizes, and ecological roles.
“The surviving mammals still retain the same north and south bio provinces,” Flynn said. “Mammals in the north and the south are very different from each other, which is different than other mass extinctions where it seems to be much more uniform.”
More than a window into the past, this research highlights how ecosystems respond to sudden global change. Conducted on public lands managed by the U.S. Bureau of Land Management, the study underscores the importance of protecting landscapes that preserve deep time stories still waiting to be uncovered.
At the Mayborn Museum Complex, research like this—led by scientists we work closely with—helps inform how we interpret fossils, ecosystems, and extinction for public audiences. These discoveries remind us that Earth’s history is not defined by gradual decline, but by moments of extraordinary vitality, abruptly transformed.
Daniel Peppe, Ph.D., associate professor of geosciences at Baylor University