Dinosaurs struggled to survive long before asteroid hit

For the study in the Proceedings of the National Academy of Sciences, researchers combed through fossil records from around the world and performed a statistical analysis showing that various species of dinosaurs were going extinct at a faster pace than new ones were emerging for a period of at least 40 million years prior to the cosmic debris that smashed into what is modern-day Mexico. "We were not expecting this result," said lead author Manabu Sakamoto, a paleontologist at the University of