New research suggests that dinosaur populations were thriving in North America before the asteroid impact 66 million years ago that caused mass extinction. Scientists analyzed fossils from a rock formation in New Mexico, dating them to around 400,000 years before the asteroid strike. This challenges the idea that dinosaurs were in decline. The findings were published Thursday in the journal Science. Differences between species found in New Mexico and Montana suggest diverse dinosaur communities existed. However, experts caution that evidence from one location might not represent global trends. Further research is needed to understand the global picture before the asteroid crash.