kenozoikum

Kenozoikum, or the Cenozoic era in English, is the current major interval on the geologic timescale. It began around 66 million years ago, after the Cretaceous–Paleogene (K-Pg) extinction event, and continues to the present. The era is characterized by the rise and diversification of modern organisms, especially mammals, birds, and flowering plants, along with significant climatic changes and tectonic activity.

The Kenozoikum is subdivided into three periods: Paleogene, Neogene, and Quaternary. The Paleogene spans from about 66 to 23 million years ago and marks the early diversification of mammals and birds after the K-Pg boundary. The Neogene, from roughly 23 to 2.6 million years ago, includes further evolutionary diversification and the development of many modern plant and animal groups. The Quaternary, from about 2.6 million years ago to the present, features repeated glaciations and the rapid evolution and global spread of humans. In many regional schemes, the Quaternary is further divided into the Pleistocene and the Holocene.

Key themes of the era include the recovery and expansion of terrestrial ecosystems after the mass extinction, the rise of grasslands in some regions, and substantial climate fluctuations that influenced global biodiversity and biogeography. Plate tectonics continued to reorganize continents and oceans, affecting ocean currents and climate. The late Quaternary saw the emergence of anatomically modern humans and the development of complex societies.

The name kenozoikum reflects the idea of a relatively new life on Earth, and the term is used in many languages to denote the Cenozoic era in the standard geologic timescale.