The Cretaceous Period was a geological period spanning from approximately 145 to 66 million years ago. It was the last period of the Mesozoic Era, following the Jurassic and preceding the Paleogene. Notable characteristics include the dominance of dinosaurs, the emergence of flowering plants, and a high sea level. The period ended with a major extinction event, the Cretaceous-Paleogene (K-Pg) extinction, which wiped out non-avian dinosaurs and many other species.