History of Earth the late Paleozoic. The Mesozoic ("middle life") era lasted from 251 Ma to Ma. It is subdivided into the Triassic, Jurassic, and Cretaceous periods. The era began with the Permian–Triassic extinction event, the most severe extinction event in the fossil record; 95% of the species on Earth died out. It ended with the Cretaceous–Paleogene extinction event that wiped out the dinosaurs.. The Cenozoic ("new life") era began at Ma, and is subdivided into the Paleogene, Neogene, and Quaternary periods. These three periods are further split into seven sub-divisions, with the Paleogene composed of The Paleocene, Eocene, and Oligocene, the Neogene
John Day Fossil Beds National Monument originated during the late Jurassic and early Cretaceous, about 118 to 93 million years ago. Northeastern Oregon was assembled in large blocks (exotic terranes) of Permian, Triassic, and Jurassic rock shifted by tectonic forces and accreted to what was then the western edge of the North American continent, near the Idaho border. By the beginning of the Cenozoic era, 66 million years ago, the Blue Mountains province was uplifting (that is, was being pushed higher by tectonic forces), and the Pacific Ocean shoreline, formerly near Idaho, had shifted to the west. Volcanic eruptions about 44 million years ago during the