New Mexico Fossils Suggest Dinosaurs Thrived Right Before Extinction

A 2025 Science study of the Naashoibito Member in New Mexico’s San Juan Basin dates fossils to roughly the final 380,000 years before the mass extinction, revealing a diverse, thriving dinosaur ecosystem that included Tyrannosaurus, Torosaurus and Alamosaurus—challenging the long-held view of a global dinosaur decline. The site shows two distinct regional communities, but experts caution this is one location and not a worldwide census, so more dated sites are needed to confirm whether the end of the dinosaurs was the result of an external catastrophe or a broader decline.