Dinosaurs Thrived Until Asteroid Impact, New Study Reveals

Recent research has unveiled that dinosaurs were thriving in diverse ecosystems across North America until the catastrophic asteroid impact 66 million years ago, challenging the longstanding belief that these creatures were in decline prior to their sudden extinction.

A study published in Science on October 23, 2025, led by Andrew Flynn of New Mexico State University, analyzed fossils from the Naashoibito Member of the Ojo Alamo Formation in northwestern New Mexico. Utilizing argon isotope decay and paleomagnetic analysis, the team determined that these fossils date to approximately 340,000 years before the asteroid impact—a brief period in geological terms. newsroom.nmsu.edu

The fossil assemblage includes species such as the massive sauropod Alamosaurus, the formidable Tyrannosaurus, and crested hadrosaurs, indicating a vibrant and diverse dinosaur community up until the catastrophic event. newsroom.nmsu.edu

"Without this impact, they weren’t on their way out," Flynn stated, emphasizing that the asteroid impact was the primary driver of their extinction. sciencenews.org

The study also highlights the existence of distinct "bioprovinces" of dinosaurs, shaped by climate and geography, suggesting that dinosaur communities were more diverse and regionally distinct than previously thought. sciencedaily.com

These findings challenge the hypothesis that dinosaurs were in decline before the asteroid impact, suggesting instead that their extinction was sudden and directly linked to the catastrophic event. sciencedaily.com

The research underscores the importance of precise fossil dating and regional studies in understanding the dynamics of prehistoric ecosystems and the events leading to mass extinctions.