Dinopedia
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System (period) Series Stage (age) Lower boundary, Ma
Quaternary Pleistocene Gelasian 2.58
Neogene Pliocene Piacenzian Golden spike3.600
Zanclean Golden spike5.333
Miocene Messinian Golden spike7.246
Tortonian Golden spike11.63
Serravallian Golden spike13.82
Langhian Golden spike15.98
Burdigalian 20.44
Aquitanian Golden spike23.03
Paleogene Oligocene Chattian older
Subdivisions and "golden spikes" according to IUGS as of September 2023[1]
Neogene

The Neogene is the second geologic period of the Cenozoic era, correspondind to the Neogene system of the Cenozoic erathem in stratigraphy. It lasted from about 23.03 million years ago to 2.58 million years ago and consists of the Miocene and Pliocene epochs. The Neogene follows the Chattian age of the Paleogene, and is followed by the Gelasian age of the Quaternary period. With a duration of 20.45 million years, Neogene is only slightly longer than the Norian age of the Triassic period, and, apart from the Quaternary, this is the shortest period of the Phanerozoic eon. During Neogene, mammals and birds continued to evolve into modern forms, while other groups of life remained relatively unchanged.

The terms Neogene System (formal) and upper Tertiary System (informal) describe the rocks deposited during the Neogene Period.

Definition[]

The Global Stratotype Section and Point (GSSP) of the Neogene system was ratified in 1996. The lower boundary is fixed in Lemme-Carrioso Section in Italy. The base of Chron C6Cn.2n as well as the first appearance of the planktonic foraminifer Paragloborotalia kugleri, the last appearance of Reticulofenestra bisecta and oxygen isotopic event Mi-1 are the indicators of the beginning of this period.[2]

The Neogene period ended at the end of the Pliocene epoch, just before the beginning of the Quaternary period. However, there is a movement amongst geologists (particularly Neogene Marine Geologists) to also include ongoing geological time (Quaternary) in the Neogene, while others (particularly Quaternary Terrestrial Geologists) insist the Quaternary to be a separate period of distinctly different record. The somewhat confusing terminology and disagreement amongst geologists on where to draw what hierarchical boundaries, is due to the comparatively fine divisibility of time units as time approaches the present, and due to geological preservation that causes the youngest sedimentary geological record to be preserved over a much larger area and reflecting many more environments, than the slightly older geological record. By dividing the Cenozoic era into three (arguably two) periods (Paleogene, Neogene, Quaternary) instead of 7 epochs, the periods are more closely comparable to the duration of periods in the Mesozoic and Paleozoic eras.

Paleogeography[]

Some continental movement 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.

Neogene life[]

Marine and continental flora and fauna have a modern appearance. In response to the cooler, seasonal climate, tropical plant species gave way to deciduous ones and grasslands replaced many forests. Eucalyptus fossil leaves occur in the Miocene of New Zealand, where the genus is not native today, but have been introduced from Australia.

The reptile group Choristodera became extinct in the early part of the period, while the amphibians known as Allocaudata disappeared at the end. Mammals and birds continued to be the dominant terrestrial vertebrates, and took many forms as they adapted to various habitats. Whales became the largest marine mammals while proboscideans became the largest on land. Grasses therefore greatly diversified, and herbivorous mammals evolved alongside it, creating the many grazing animals of today such as horses, antelope, and bison. These diverse ungulates were hunted by new, progressive predators: felids, ursids, canids and mustelids. The first hominins, the ancestors of humans may have appeared in southern Europe and migrated into Africa. The first bipedal primates (such as Ardipithecus) appeared in Africa near the end of the Miocene. Australopithecus, the next ancestors of humans, probably learned to make primitive tools by the end of the Pliocene.

References[]

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