Neogene Period

Neogene Period
Name	Neogene
Time start	23.03
Time end	2.58
Unit	Period
Era	Cenozoic
Color	#ffcc99
Caption	Grassland expansion and hominin evolution during the Neogene

Neogene Period The Neogene Period marks a major interval of the Cenozoic Era characterized by profound shifts in climate change, plate tectonics, and biological evolution that set the stage for modern biogeography. Spanning from the end of the Paleogene to the beginning of the Quaternary, this interval witnessed the expansion of grasslands, the diversification of mammals, and key steps in hominin evolution that culminated in the rise of Homo.

Definition and Timeframe

The Neogene is formally bounded by chronostratigraphic divisions tied to the International Commission on Stratigraphy and magnetostratigraphic markers used in studies by the Geological Society of America, United States Geological Survey, and researchers publishing in journals such as Nature (journal), Science (journal), and the Journal of Geology. Its lower boundary follows the Oligocene–Neogene transition recognized in sections like the Aquitaine Basin and Mediterranean basin stratotypes, while its upper limit precedes the Pleistocene and is correlated to isotope events used by the Intergovernmental Panel on Climate Change contributors and datasets from the Ocean Drilling Program and Integrated Ocean Drilling Program cores.

Stratigraphy and Subdivision

Stratigraphic frameworks for the Neogene employ stages and ages defined by the International Commission on Stratigraphy and regional units established in regions such as the European Land Mammal Ages, the North American Land Mammal Ages, the South American Land Mammal Ages, and the Asian Land Mammal Ages. Subdivisions commonly referenced include the Miocene and Pliocene epochs with regional stage names like the Aquitanian, Burdigalian, Langhian, Serravallian, Tortonian, Messinian, Zanclean, and Piacenzian. Biostratigraphic correlations rely on first and last appearances of taxa documented from formations such as the Siwalik Group, Siwalik Hills, Burgess Shale (earlier but comparative), Chesapeake Group, Gomphothere Localities, and the Laetoli deposits, while magnetostratigraphy references the Brunhes–Matuyama reversal and polarity chrons recorded in cores like those from the Leg 154 of the Deep Sea Drilling Project.

Paleoclimate and Oceanography

Neogene climate evolution is reconstructed using proxies from foraminifera assemblages in Atlantic Ocean and Pacific Ocean cores, stable isotope records from Greenland ice cores proxies, and plant macrofossils from the Siwalik and Florissant Formation. Cooling trends documented in work by researchers at Lamont–Doherty Earth Observatory and institutions like the Scripps Institution of Oceanography coincide with declining atmospheric carbon dioxide concentrations inferred by studies from the Paleoclimatology community and modeled in ensembles applied by the Hadley Centre and NOAA. Sea-level changes tied to Antarctic and Greenland ice growth affected the Mediterranean Sea evaporite events such as the Messinian Salinity Crisis and currents like the development of the modern Gulf Stream and reorganization of the Southern Ocean circulation influenced by the opening and closing of gateways like the Isthmus of Panama and the Tethys Seaway.

Tectonics and Paleogeography

Major plate motions during the Neogene were driven by interactions among plates documented by the United States Geological Survey and the European Plate Observing System, notably collision and uplift events at the Himalaya and the Alps, rifting in the East African Rift, and subduction zone reorganizations along the Andes and the Cascadia subduction zone. These tectonic processes shaped regional paleogeography of areas including the Mediterranean Basin, Caribbean Plate, Antarctic Peninsula, New Zealand, Iberian Peninsula, and the Bering Land Bridge, which in turn influenced migrations recorded in the Great American Biotic Interchange between the North America and South America continents.

Evolution and Biodiversity

The Neogene saw the radiation of many modern clades documented in fossil Lagerstätten and museum collections at institutions such as the Smithsonian Institution, Natural History Museum, London, and the American Museum of Natural History. Among vertebrates, notable expansions occurred in Cetacea, Carnivora, Rodentia, and Ungulates adapted to open habitats; plants shifted with the spread of Poaceae (true grasses) and the evolution of C4 photosynthesis documented in paleobotanical studies at universities like Harvard University and University of California, Berkeley. Marine biodiversity patterns include diversification in bivalves, gastropods, and reef-building corals affected by temperature and nutrient shifts analyzed by researchers at the Woods Hole Oceanographic Institution and the Monterey Bay Aquarium Research Institute.

Major Faunal and Floral Events

Key Neogene events include the expansion of savanna and steppe ecosystems tied to grasses like Poaceae and the radiation of grazers such as Equidae and Bovidae; faunal turnovers like the Messinian Salinity Crisis impact on Mediterranean faunas; the Great American Biotic Interchange reshaping New World mammal assemblages; and megafaunal trends preceding Quaternary extinctions discussed in works from the Paleobiology Database and scholars at institutions including University of Cambridge and Yale University. Paleobotanical shifts recorded in the Siwalik and Fayum formations show the rise of open-habitat flora and regionally distinct assemblages in places like Eurasia, Africa, and South America.

Human Origins and Hominin Evolution

The Neogene hosts crucial stages in hominin evolution documented at fossil sites such as Laetoli, Olduvai Gorge, Hadar, Sterkfontein, Koobi Fora, and Gona with key taxa described in publications from researchers affiliated with University of Oxford, University College London, Max Planck Institute for Evolutionary Anthropology, and the Institute of Human Origins. Discoveries include australopithecines, early Homo species, and stone tool industries linked to the Oldowan and later Acheulean traditions, informing debates addressed at conferences like the Paleontological Society meetings. Climatic and environmental reconstructions from sites across East Africa, the Ethiopian Rift, and the Afar Triangle underscore how tectonic uplift, habitat fragmentation, and resource distributions influenced hominin morphology, locomotion, and dispersal patterns into Eurasia via corridors such as the Levantine Corridor and across land bridges documented by paleogeographers.

Category:Geological periods