Scientists have discussed for a long time whether dinosaurs were getting fewer before a huge asteroid hit Earth about 66 million years ago. The asteroid caused one of the biggest extinctions in Earth’s history. A new study says that dinosaurs were still doing well in some parts of North America before the impact. The research, published in Science, looked at fossils from the Kirtland Formation in northern New Mexico. By studying small volcanic glass pieces and magnetic rocks, scientists found that the fossils were from about 400,000 years before the asteroid crash. The fossils include Tyrannosaurus rex, long-necked dinosaurs, and a horned dinosaur like Triceratops. This shows that many kinds of dinosaurs still lived on Earth at that time.

Experts say that this discovery is exciting but only shows what happened in one area. Paleontologist Daniel Peppe said that dinosaurs lived in different groups in different regions before they disappeared. Other scientists, like Mike Benton, said that more research is needed. Because carbon dating does not work on old fossils, scientists use the rocks around them to find their age. More studies may show what dinosaurs lived on Earth just before the asteroid hit.