The Cenozoic era started 65.5 million years ago and still goes on today. The Cenozoic started when the dinosaurs went extinct. Important events include the Paleocene-Eocene Thermal Maximum, the evolution of whales, the Eocene-Oligocene extinction, the evolution of horses, the Middle Miocene Disruption, the evolution of humans, the Ice Ages, the Toba Catastrophe, and the Quaternary extinction.