Neogene is a term often used in geology and paleontology to describe a specific period of time in Earth's history. It refers to the era spanning from approximately 23.03 to 2.58 million years ago. There are several synonyms that can be used to describe this same period, including the Tertiary Period, the Cainozoic Era, and the Age of Mammals. Each of these terms refers to the same time period, but may be preferred in different regions or by different scientific communities. No matter which term is used, they all describe a time in which mammals began to thrive and diversify, leading to the rise of many modern species.