New evidence suggests that dinosaurs were thriving just before a massive asteroid struck Earth 66 million years ago. Contrary to long-held beliefs that these magnificent creatures were already in decline, recent fossil discoveries paint a picture of rich and diverse dinosaur communities right up to their sudden end.
Revolutionary Dating of Late Cretaceous Fossils
Scientists have re-examined rock layers in New Mexico’s San Juan Basin, specifically the Naashoibito Member, utilizing advanced radiometric and magnetic dating techniques. This meticulous research pinpoints the youngest dinosaur-bearing layers to approximately 66.38 million years ago, a mere 350,000 years before the cataclysmic extinction event.
This revised timeline dramatically shifts previous estimates of around 70 million years, indicating that dinosaurs in New Mexico flourished almost until the very end of the Cretaceous period. This period aligns closely with the presence of other well-known dinosaurs, such as Triceratops, found in northern regions like Montana. The research team identified a vibrant ecosystem populated by various species, including large duck-billed hadrosaurs and the enormous sauropod Alamosaurus, demonstrating a thriving environment just prior to the impact.
A World of Diverse Dinosaur Communities
These updated dates highlight the existence of distinct dinosaur communities across different geographical areas. For instance, the southern fossils from New Mexico reveal crested duckbills and colossal sauropods, while northern sites in Montana and the Dakotas yield evidence of Triceratops and flat-headed hadrosaurs. This “provinciality” strongly suggests that climate variations, rather than a widespread faunal collapse, accounted for these regional differences.
Paleontologist Steve Brusatte remarked that there was “no sign that these dinosaurs were in any trouble, or that anything unusual was happening to them, or that they were in any type of long-term decline.” Co-author Andrew Flynn echoed this sentiment, confirming that the dinosaurs “were not on their way out” before the asteroid impact.
A video exploring this discovery further could provide additional insights into the fascinating world of Late Cretaceous dinosaurs.