Neogene

Neogene
Name	Neogene
Color	#FFB6C1
Time start	23.03
Time end	2.58
Time unit	Ma
Chronology	Cenozoic
Preceded by	Paleogene
Followed by	Quaternary

Neogene The Neogene was a geological period spanning from about 23.03 to 2.58 million years ago that marked major transformations in Earth’s climate and biosphere following the Paleogene. It encompasses dramatic shifts recorded across sedimentary basins such as the Siwalik Hills and the Balkans, and in marine successions like the Mediterranean Sea deposits and the North Atlantic stratigraphy. Key research programs and institutions including the International Commission on Stratigraphy, the United States Geological Survey, the Natural History Museum, London, and the Smithsonian Institution have refined its chronology through studies of sequences from sites such as the La Brea Tar Pits, the Olduvai Gorge, and the Pisco Formation.

Definition and Chronology

The Neogene is formally subdivided into the Miocene and the Pliocene epochs, with boundaries defined by events tied to magnetostratigraphy and biostratigraphy employed by the International Commission on Stratigraphy and applied in regional studies at locations like the Gulf of Mexico and the Eastern Pacific. Global chronostratigraphic charts correlate Neogene stages to regional schemes used in the European Geological Timescale, the Asian continental sequences, and Neogene records from the African Rift Valley and the Andes. Dating methods developed by teams at institutions such as the Max Planck Society and the Oak Ridge National Laboratory — including radiometric techniques used at the Berkeley Geochronology Center — constrain Neogene ages, while paleomagnetic reversal records tied to the Brunhes–Matuyama reversal and other polarity chrons provide global correlation.

Geology and Paleoenvironments

Neogene sedimentary deposits occur in marine basins like the Mediterranean Sea evaporites and in continental systems such as the Siwalik Hills fluvial sequences and the Sahara-adjacent basins. Volcanic successions in the East African Rift and the Eifel region document magmatic pulses associated with basin evolution studied by researchers at the Geological Survey of India and the British Geological Survey. Paleosols, lacustrine deposits in the Pannonian Basin, and glacigenic sediments in higher latitudes record environmental gradients used by paleoenvironmental projects based at the University of California, Berkeley, the University of Oxford, and ETH Zurich. Biostratigraphic markers like diatom assemblages from the North Pacific and foraminiferal zones from the Southern Ocean provide correlation across the Tethys-derived basins.

Climate Evolution

During the Neogene the planet cooled from warm Miocene Climatic Optimum conditions toward the colder Pliocene leading into Quaternary glaciations recognized in records from the Greenland Ice Sheet, Antarctic Ice Sheet, and marine cores recovered by programs such as the International Ocean Discovery Program and the Deep Sea Drilling Project. Atmospheric CO2 reconstructions from proxies developed at the Lamont–Doherty Earth Observatory and the Paleoceanography and Paleoclimatology studies show declines tied to changes in ocean circulation, including shifts in the North Atlantic Drift, the closure of seaways like the Tethys Sea remnants and the Central American Seaway, and the establishment of modern currents influencing monsoon systems monitored by research groups at the Indian Institute of Science and the Chinese Academy of Sciences.

Fauna and Flora

The Neogene witnessed major faunal turnovers across continents: expansion of grassland-adapted taxa in association with the spread of Poaceae grasslands, diversification of grazing mammals documented in the Siwalik fossil beds and Great Plains faunas, and radiation events evident in marine groups such as cetaceans recorded at Peruvian fossil sites and in the Mediterranean. Notable vertebrate lineages including the ancestors of modern Equidae, Bovidae, and Canidae evolved in response to open habitats revealed in assemblages curated by the American Museum of Natural History and the Natural History Museum, London. Avian radiations paralleled these trends with fossils from the Fossil Butte National Monument and the Messel Pit. Plant assemblages shifted from woodland-dominated floras to communities rich in grass and drought-tolerant taxa, documented in palynological records studied by teams at the Smithsonian Tropical Research Institute and the Kew Gardens.

Tectonics and Paleogeography

Plate reorganizations during the Neogene affected the uplift of major orogens such as the Himalayas, the Andes, and the Alps, driven by collisions and subduction processes analyzed by groups at the Scripps Institution of Oceanography and the German Research Centre for Geosciences (GFZ). The progressive closure of the Central American Seaway and changes in the Tethys domain reconfigured ocean gateways and influenced biogeographic dispersal between faunas of North America and South America culminating in the Great American Biotic Interchange. Rift-related extension in the East African Rift System shaped basins that yielded critical fossil sequences such as those from the Hadar Formation and Laetoli, studied by collaborations including the National Museums of Kenya and the University of Addis Ababa.

Human Evolution and Hominins

The Neogene contains pivotal records for hominin evolution with key sites in the East African Rift Valley—including Hadar, Laetoli, Olduvai Gorge, and Koobi Fora—yielding fossils attributed to lineages studied by teams from the Max Planck Institute for Evolutionary Anthropology, the Leakey family research groups, and university consortia such as the University of Cambridge and the University of Chicago. Morphological and behavioral inferences from australopith and early Homo specimens intersect with paleoenvironmental reconstructions from institutions like the Natural History Museum, London and the National Geographic Society, illuminating links between climatic shifts, tectonic change, and the emergence of traits associated with later hominins found in Pliocene deposits at sites related to the origin of Homo erectus and other early Homo taxa.

Category:Geologic periods