New fossil analysis reveals that dinosaurs thrived in diverse ecosystems until the asteroid impact ended their dominance. Their abrupt extinction reshaped Earth’s ecosystems and set the stage for the rise of mammals.
For many years, scientists assumed that dinosaurs had already were in declineboth in number and diversity, long before an asteroid impact ended their dominance 66 million years ago.
A new study, led by a team of researchers from Baylor University, New Mexico State University, the Smithsonian Institution and an international group, and recently published in Sciencecome now challenge this assumption.
According to the results of the study, instead of fighting for survival, before the event that led to their extinction, the dinosaurs were thriving.
Fossils found in rock layers in northwestern New Mexico capture an overlooked moment in Earth’s deep past: the limb Naoshoibito from the Kirtland Formation, scientists have identified signs of dinosaur ecosystems active and healthywhich persisted until shortly before the asteroid impact.
Using high-precision dating methods, the team determined that these fossils have 66.4 to 66 million yearswhich places them at the Cretaceous-Paleogene limit, the period associated with the mass extinction eventexplains .
“The Naashoibito dinosaurs lived at the same time as the famous Hell Creek species in Montana and the Dakotas,” he said. Daniel Peppeassociate professor of geosciences at Baylor University. “They were not in decline – were vibrant and diverse communities“.
The New Mexico fossil record presents a picture that contrasts sharply with previous interpretations. Instead of showing signs of fragilitydinosaur populations in North America were healthy and variedwith clear regional differences.
Through ecological and biogeographic analyses, researchers discovered that dinosaurs in western North America occupied “bioprovinces” distinct, shaped by temperature variations rather than physical barriers like rivers or mountain ranges.
“Our study shows that dinosaurs were not about to disappear when the mass extinction occurred,” says Andrew Flynnprofessor at New Mexico State University and first author of the study.
“They were doing very well, they were prosperingand it appears to have been the asteroid impact that eliminated them. This contradicts a long-established idea that there would have been a long-term decline in dinosaur diversity before the mass extinction, making them more prone to extinction,” he adds.
The asteroid impact brought the age of dinosaurs to a sudden ends, but the ecological systems they left behind influenced what followed, according to researchers.
In the space of 300,000 years, mammals began to diversify quickly, adapting to new diets, body sizes and roles in recovering ecosystems.
Os temperature standards that once shaped dinosaur communities continued into the Paleocene, helping to guide the way life developed. recovered after the global catastrophe.
“Surviving mammals maintained the same bioprovinces north and south,” said Flynn. “The mammals of the north and south are very different from each other, which differs from other mass extinctions where everything seems to be much more uniform.”
This investigation does more than clarify the final chapter the history of dinosaurs. It also highlights both resilience and vulnerability of life on Earth.
By refining the chronology of the last days of the dinosaurs, the study demonstrates that their extinction It wasn’t a gradual declinebut rather a sudden end to a world full of diversity, abruptly interrupted by a rare cosmic event.
