The Paleogene is a major geological period within the Cenozoic Era, spanning approximately 66 to 23 million years ago. This epoch immediately followed the Cretaceous Period and is subdivided into the Paleocene, Eocene, and Oligocene. It is recognized for significant global environmental changes, including the recovery of flora and fauna after a mass extinction event. During the Paleogene, mammalian life diversified rapidly and underwent substantial evolution, leading to the establishment of modern ecological patterns. Climatic conditions varied throughout the period, exhibiting transitions from generally warm climates to more cooler and arid phases, which profoundly impacted global biogeography and the subsequent adaptive radiation of diverse life forms.