The Cenozoic Era represents the current geological period, commencing approximately 66 million years ago. This time span is defined by significant global shifts in climate, continental drift, and the diversification of life, particularly the rapid radiation of mammalian forms. The era is conventionally subdivided into several periods, including the Paleogene, Neogene, and the Quaternary. The Quaternary Period is notably characterized by repeated cycles of glacial advance and retreat, which have profoundly shaped global geography and contributed to the evolution of modern biodiversity.