Neogene Period, the name of the more recent of two periods (the other being the Paleogene Period) into which some geologists divide the Cenozoic Era. The Neogene began about 23,000,000 years ago and extends to the present. It includes the Miocene, Pliocene, and Pleistocene epochs. Most geologists today divide the Cenozoic Era into the Tertiary and Quaternary periods instead of the Neogene and Paleogene periods.