Scientists have long debated the status of dinosaurs before the asteroid impact that caused mass extinction 66 million years ago. Recent research indicates that dinosaur populations were still flourishing in North America just prior to this catastrophic event.
Daniel Peppe, a paleontologist at Baylor University and co-author of the study, emphasized that “dinosaurs were quite diverse and now we know there were quite distinct communities” inhabiting the region before their abrupt extinction.
The findings stem from an analysis of part of the Kirtland Formation in northern New Mexico, an area known for its rich fossil record for over a century. Researchers determined that the fossils and the surrounding rocks date back approximately 400,000 years before the asteroid impact, a relatively brief interval in geological terms.
This dating was achieved by examining tiny volcanic glass particles within sandstone and analyzing the orientation of magnetic minerals in the mudstone of the rock formation. Peppe noted, “The animals deposited here must have been living close to the end of the Cretaceous,” the final period of the dinosaur era.
The study”s results were published in the journal Science on Thursday. The research reveals that the species of dinosaurs discovered in New Mexico differ from those found at a Montana site previously dated to the same period, challenging the notion that dinosaurs were in decline.
Among the fossils identified from the New Mexico site are Tyrannosaurus rex and a horned herbivore reminiscent of Triceratops. While the findings are promising, experts not involved in the research caution that data derived from a single location may not reflect broader trends across North America or globally.
“This new evidence about these very late-surviving dinosaurs in New Mexico is very exciting,” stated Mike Benton, a paleontologist at the University of Bristol. However, he added, “This is just one location, not a representation of the complexity of dinosaur faunas at the time all over North America or all over the world.”
Paleontologist and co-author Andrew Flynn from New Mexico State University highlighted the challenges of accurately dating dinosaur fossils, mentioning that easily datable materials like carbon do not survive in fossilized remains. Instead, researchers need to find surrounding rocks with distinct characteristics to establish their age.
Further investigations could provide a more complete understanding of the variety of dinosaur species present worldwide just before the asteroid impact, according to Flynn.
