New Mexico Fossils Reveal Thriving, Regionally Distinct Dinosaur Communities Before Extinction

Recent research on dinosaur fossils from the Naashoibito Member of the Kirtland Formation in northwestern New Mexico challenges the long-held belief that non-avian dinosaurs were in decline before their extinction. Using improved dating techniques, scientists have determined that these dinosaurs lived between 66.4 and 66 million years ago, just before the asteroid impact that caused mass extinction. The fossils reveal that dinosaur communities were diverse, thriving, and regionally distinct across western North America, divided by temperature-related bioprovinces rather than physical barriers. This evidence counters the notion of a gradual decline and supports the idea that dinosaurs were flourishing until the sudden asteroid impact abruptly ended their era. The findings also provide new insights into the ecosystems that existed immediately before the mass extinction, helping to reshape understanding of the late Cretaceous period. These discoveries highlight the San Juan Basin as a crucial site for studying the final days of non-avian dinosaurs.