Palaeogene
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| Palaeogene | |
|---|---|
 | |
| Name | Palaeogene |
| Color | #ffe4b5 |
| Time start mya | 66 |
| Time end mya | 23.03 |
| Period | Cenozoic |
| Preceded by | Cretaceous |
| Followed by | Neogene |
Palaeogene The Palaeogene was the first major epochal interval of the Cenozoic spanning the interval from about 66 to 23.03 million years ago and marks the interval after the end of the Cretaceous–Paleogene extinction event and before the rise of Neogene faunas. It encompasses critical early Cenozoic events including the recovery from mass extinction, major climate perturbations such as the Paleocene–Eocene Thermal Maximum, and rapid radiations among mammals, birds, and angiosperms documented in numerous stratigraphic and fossil records across continents, basins, and orogens.
Overview
The Palaeogene comprises three formally recognized epochs that together frame early Cenozoic Earth history and link the aftermath of the Chicxulub impact and the end of the Maastrichtian stage to later Miocene-related developments; these epochs record biological recoveries preserved in classic localities like the Hell Creek Formation, the London Clay Formation, and the Willwood Formation. Global changes in climate, biota, and geodynamics during the Palaeogene are traced in marine sequences such as the Foraminifera-rich cores from the Deep Sea Drilling Project and terrestrial archives from the Eocene Green River Formation, the Paleocene Mancos Group, and fossil sites linked to collectors and institutions including the Smithsonian Institution and the Natural History Museum, London. Key researchers associated with early Cenozoic studies include figures tied to expeditions and analyses at the American Museum of Natural History, the Geological Survey of Canada, and university groups at University of California, Berkeley and University of Oxford.
Stratigraphy and Subdivisions
Stratigraphic practice divides the Palaeogene into the Paleocene, Eocene, and Oligocene epochs, each subdivided into stages that include the Danian, Selandian, Thanetian, Ypresian, Lutetian, Bartonian, Priabonian, Rupelian, and Chattian that are correlated via biostratigraphy, magnetostratigraphy, and chemostratigraphy applied by international bodies such as the International Commission on Stratigraphy and documented in regional chronostratigraphic charts produced by the United States Geological Survey and the British Geological Survey. Marine microfossil zonations based on planktonic foraminifera, nannofossils, and benthic assemblages tie sections from the Mediterranean Sea to the North Sea Basin and the Equatorial Pacific and are calibrated against paleomagnetic chrons and ash beds correlated to isotope excursions recognized globally at GSSP candidates proposed in collaboration with institutions like the Geological Society of America.
Paleoclimate and Paleoenvironment
Palaeogene climates show a progression from warm, greenhouse conditions in the early Paleocene and peak warmth during the Paleocene–Eocene Thermal Maximum—a transient hyperthermal recorded in oxygen isotope excursions and carbon isotope anomalies—toward cooling and Antarctic glaciation inception in the Oligocene driven by plate motions and ocean gateway changes including the opening of the North Atlantic Ocean and the isolation of Antarctica via the Tasman Gateway and Drake Passage. Atmospheric CO2 reconstructions derived from proxy studies linked to researchers at Scripps Institution of Oceanography and isotope work from cores recovered by the International Ocean Discovery Program indicate high early Palaeogene greenhouse gas levels with subsequent decline associated with weathering fluxes, organic carbon burial, and the evolution of terrestrial floras such as expansions of angiosperm-dominated forests preserved in lignite and coal-bearing successions in the Eocene Green River Formation and the Fushun Coalfield.
Life and Evolutionary Trends
Biotic turnover following the Cretaceous–Paleogene extinction event set the stage for rapid mammalian, avian, and floral diversification; early Palaeogene faunas include stem groups and newly radiated clades recorded in fossil-rich sites like the Fayum Depression (paleogene mammals), the Messel Pit (Eocene vertebrates), the Bighorn Basin (vertebrate succession), and the Willwood Formation (mammal evolution). Major evolutionary trends include the adaptive radiation of Placentalia and early orders such as Primates, Perissodactyla, and Artiodactyla, the diversification of Aves from Cretaceous survivors, and continued angiosperm expansion with important plant fossils found at the Florissant Fossil Beds National Monument and in coal seams studied by the United States Forest Service. Marine ecosystems rebuilt with new radiations of teleost fishes, benthic foraminifera turnovers, and the emergence of modern cetacean lineages documented in the Eocetus-bearing strata and later odontocete and mysticete records from basins studied by the Natural History Museum of Los Angeles County.
Tectonics, Paleogeography, and Sea Level
Plate tectonic reconfigurations during the Palaeogene included continued opening of the North Atlantic Ocean with seafloor spreading between the Greenland Plate and the Eurasian Plate, ongoing uplift of the Himalaya related to the India–Eurasia collision, and arc-continent interactions along the Andean margin; these drove changes in ocean circulation, monsoon evolution tied to the Asian Monsoon onset, and regional subsidence patterns recorded in the Gulf of Mexico and the North Sea Basin. Eustatic sea level fell and rose in response to ice-volume changes and thermal expansion with pronounced transgressive-regressive cycles preserved in sequence stratigraphic packages described in reports by the United States Geological Survey and the Geological Survey of Canada and correlated to global stacks developed by teams at Columbia University and the University of Cambridge.
Regional Geology and Important Formations
Important Palaeogene formations include the London Clay Formation (North Sea–English Basin marine clays), the Eocene Green River Formation (lacustrine oil shale and fossil biotas), the Willwood Formation and Bighorn Basin successions (terrestrial mammal sequences), the Messel Pit lagerstätte (Eocene vertebrates and insects), the Fayum Depression (Oligocene–Eocene Egyptian faunas), the Paleocene Fort Union Formation and the Hell Creek Formation transitional sections, and marine sections such as the Bach Long Vi Formation and Oregon Coast deposits studied by the United States Geological Survey and university research groups. These formations have yielded key fossils cataloged in collections at the American Museum of Natural History, the Natural History Museum, London, the Smithsonian Institution, and the Paleontological Institute of the Russian Academy of Sciences and continue to inform biostratigraphic, tectonic, and paleoclimatic syntheses by international collaborations including the International Union of Geological Sciences and the International Commission on Stratigraphy.