Neogene

The Neogene (/ˈn.əˌn/ NEE-ə-jeen),[6][7] informally Upper Tertiary or Late Tertiary, 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 Mya. 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]

Neogene
23.03 ± 0.3 – 2.588 ± 0.04 Ma
Chronology
Etymology
Name formalityFormal
Usage information
Celestial bodyEarth
Regional usageGlobal (ICS)
Time scale(s) usedICS Time Scale
Definition
Chronological unitPeriod
Stratigraphic unitSystem
Time span formalityFormal
Lower boundary definition
Lower boundary GSSPLemme-Carrosio Section, Carrosio, Italy
44.6589°N 8.8364°E / 44.6589; 8.8364
GSSP ratified1996[4]
Upper boundary definition
Upper boundary GSSPMonte San Nicola Section, Gela, Sicily, Italy
37.1469°N 14.2035°E / 37.1469; 14.2035
GSSP ratified2009 (as base of Quaternary and Pleistocene)[5]
Atmospheric and climatic data
Mean atmospheric O
2
content
c. 21.5 vol %
(108 % of modern)
Mean atmospheric CO
2
content
c. 280 ppm
(1 times pre-industrial)
Mean surface temperaturec. 14 °C
(0 °C above modern)

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.[10] 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 over the course of the Neogene, culminating in a series of continental glaciations in the Quaternary Period that follows.


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