Overview
- Researchers report in Science that late Cretaceous fossils from New Mexico’s Naashoibito Member date to 66.4–66.0 million years ago, aligning them with the final moments before the asteroid strike.
- Detrital sanidine 40Ar/39Ar geochronology paired with magnetostratigraphy ties the New Mexico assemblage to the same interval as the well-known Hell Creek fauna.
- The decade-long field effort uncovered a diverse community including Tyrannosaurus rex, Alamosaurus, Ojoceratops and Ojoraptorosaurus, indicating robust ecosystems rather than dwindling populations.
- Ecological analyses identify distinct northern and southern bioprovinces across western North America, with temperature differences shaping separate dinosaur communities.
- The study supports an abrupt, impact-driven extinction and notes that the work was conducted on BLM-managed public lands with support from the National Science Foundation and the European Research Council.