For years, scientists thought dinosaurs were already declining before an asteroid wiped them out 66 million years ago.
But new research from Baylor University, New Mexico State University, the Smithsonian Institution, and their international partners tells a very different story — dinosaurs were doing just fine until the very end.
In northwestern New Mexico, researchers studied rock layers in the Naashoibito Member of the Kirtland Formation, located in the San Juan Basin.
These rocks preserve a detailed record of life right before the mass extinction.
Using precise dating methods, scientists found that the fossils there are between 66.4 and 66 million years old — placing them just before the asteroid struck Earth.
According to Daniel Peppe, a geoscientist at Baylor University, the dinosaurs that lived in New Mexico at that time were part of rich, diverse ecosystems.
“They were not in decline,” he said. “These were vibrant, active communities.”
In fact, these dinosaurs lived around the same time as the famous species found in Montana’s Hell Creek Formation, such as Triceratops and Tyrannosaurus rex.
The study, published in Science, reveals that dinosaurs in western North America were not only plentiful but also regionally unique.
Instead of being separated by mountains or rivers, their communities were divided by temperature differences. Dinosaurs in cooler northern areas were different from those in the warmer south — a pattern similar to modern animals that live in distinct climate zones.
Andrew Flynn, the study’s lead author from New Mexico State University, explained that the new findings overturn the long-standing idea of a slow decline.
“They weren’t dying out,” Flynn said. “They were thriving, and the asteroid suddenly ended their success. The extinction was abrupt, not gradual.”
After the asteroid impact, life on Earth changed dramatically. While the dinosaurs vanished, mammals quickly took advantage of the empty habitats.
Within about 300,000 years, mammals began to diversify in size, diet, and behavior.
Interestingly, they continued to show the same north-south regional differences that dinosaurs once had, suggesting that climate continued to shape life even after the catastrophe.
This research, conducted on public lands managed by the U.S. Bureau of Land Management, reminds us how valuable protected natural areas are for scientific discovery.
The findings show that the end of the dinosaurs was not a slow fade, but a sudden, tragic event that abruptly stopped a flourishing era of life.
It’s a powerful lesson about how quickly global change — whether from space or human activity — can reshape life on our planet.
