Kainozooisen

Kainozooisen refers to the Cenozoic Era, the current geological era which began 66 million years ago after the Cretaceous–Paleogene extinction event and continues to the present day. It is often called the "Age of Mammals" because the extinction of the non-avian dinosaurs paved the way for the diversification and dominance of mammals. This era is further divided into three periods: the Paleogene, the Neogene, and the Quaternary.

The Paleogene period, from 66 to 23 million years ago, saw the emergence of modern mammal and bird groups. It was a time of significant warming following the extinction event, followed by cooling trends. The Neogene period, from 23 to 2.6 million years ago, witnessed the continued evolution of mammals and the development of grasslands and savannas. Major mountain ranges like the Himalayas and the Alps formed during this time.

The Quaternary period, the most recent period, began 2.6 million years ago and includes the Pleistocene and the Holocene epochs. The Pleistocene was characterized by repeated glacial cycles, or ice ages, which significantly impacted global sea levels and landscapes. The Holocene, the current epoch, began about 11,700 years ago and is marked by a warmer, interglacial climate, leading to the development of human civilization. Throughout the Cenozoic, continents continued to drift to their present positions.