Neogene

Neogene
23.03 ± 0.3 – 2.588 ± 0.04 Ma PreꞒ Ꞓ O S D C P T J K Pg N
A map of Earth as it appeared 15 million years ago during the Neogene Period, Miocene Epoch
Chronology
−24 — – −22 — – −20 — – −18 — – −16 — – −14 — – −12 — – −10 — – −8 — – −6 — – −4 — – −2 — C e n o z o i c Paleogene N e o g e n e Quaternary M i o c e n e P l i o. Aquitanian Burdigalian Langhian Serravallian Tortonian Messinian Zanclean Piacenzian         ← Messinian salinity crisis[1] ← North American prairie expands[2] Subdivision of the Neogene according to the ICS, as of 2021.[3] Vertical axis: millions of years ago.
Etymology
Name formality	Formal
Usage information
Celestial body	Earth
Regional usage	Global (ICS)
Time scale(s) used	ICS Time Scale
Definition
Chronological unit	Period
Stratigraphic unit	System
Time span formality	Formal
Lower boundary definition	Base of magnetic polarity chronozone C6Cn.2n FAD of the Planktonic foraminiferan Paragloborotalia kugleri
Lower boundary GSSP	Lemme-Carrosio Section, Carrosio, Italy 44°39′32″N 8°50′11″E / 44.6589°N 8.8364°E / 44.6589; 8.8364
Lower GSSP ratified	1996[4]
Upper boundary definition	Base of magnetic polarity chronozone C2r (Matuyama). Extinction of the Haptophytes Discoaster pentaradiatus and Discoaster surculus
Upper boundary GSSP	Monte San Nicola Section, Gela, Sicily, Italy 37°08′49″N 14°12′13″E / 37.1469°N 14.2035°E / 37.1469; 14.2035
Upper GSSP ratified	2009 (as base of Quaternary and Pleistocene)[5]
Atmospheric and climatic data
Mean atmospheric O2 content	c. 21.5 vol % (100 % of modern)
Mean atmospheric CO2 content	c. 280 ppm (1 times pre-industrial)
Mean surface temperature	c. 14 °C (0.5 °C above pre-industrial)

The Neogene (/ˈniː.ədʒiːn/ NEE-ə-jeen,^[6][7]) is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period 23.03 million years ago (Mya) to the beginning of the present Quaternary Period 2.58 million years ago. It is the second period of the Cenozoic and the eleventh period of the Phanerozoic. The Neogene is sub-divided into two epochs, the earlier Miocene and the later Pliocene. Some geologists assert that the Neogene cannot be clearly delineated from the modern geological period, the Quaternary.^[8] The term "Neogene" was coined in 1853 by the Austrian palaeontologist Moritz Hörnes (1815–1868).^[9] The earlier term Tertiary Period was used to define the span of time now covered by Paleogene and Neogene and, despite no longer being recognized as a formal stratigraphic term, "Tertiary" still sometimes remains in informal use.^[10]

During this period, mammals and birds continued to evolve into modern forms, while other groups of life remained relatively unchanged. The first humans (Homo habilis) appeared in Africa near the end of the period.^[11] Some continental movements took place, the most significant event being the connection of North and South America at the Isthmus of Panama, late in the Pliocene. This cut off the warm ocean currents from the Pacific to the Atlantic Ocean, leaving only the Gulf Stream to transfer heat to the Arctic Ocean. The global climate cooled considerably throughout the Neogene, culminating in a series of continental glaciations in the Quaternary Period that followed.