Eocene

Eocene
Scotese, Christopher R.; Vérard, Christian; Burgener, Landon; Elling, Reece P.; · CC BY 4.0 · source
Name	Eocene
Period	Paleogene
Epoch start mya	56
Epoch end mya	33.9
Preceding	Paleocene
Following	Oligocene

Eocene The Eocene was an interval of the Paleogene characterized by major climatic shifts and rapid biotic turnover that influenced later Cenozoic evolution. It witnessed the diversification of many modern Mammalia orders, profound changes in Paleogene oceanography, and tectonic reorganizations that shaped present-day Eurasia, Africa, and North America. Key scientific understanding of this epoch comes from work by institutions such as the United States Geological Survey, Natural History Museum, London, and researchers linked to the Geological Society of America.

Overview

The Eocene began after the end of the Paleocene–Eocene Thermal Maximum boundary and concluded near the Eocene–Oligocene extinction event, spanning major faunal radiations recorded in fossiliferous sites studied by teams from Smithsonian Institution, Muséum national d'Histoire naturelle, and the Royal Society. Prominent fossil localities include formations investigated by researchers associated with Yale University, University of California, Berkeley, and the British Museum (Natural History). Stratigraphic work by the International Commission on Stratigraphy formalized global stages used in correlation with regional sequences from Greenland, Antarctica, India, and Patagonia.

Stratigraphy and Subdivisions

Formally subdivided into early, middle, and late intervals, stages recognized by the International Commission on Stratigraphy correlate with regional units such as the Wasatchian and Bridgerian Land Mammal Ages used by paleontologists at institutions like the American Museum of Natural History and the Field Museum. Key chronostratigraphic stages include the Ypresian, Lutetian, Bartonian, and Priabonian, each tied to type sections studied near locales such as Paris Basin, Green River Formation, and London Basin. Biostratigraphic frameworks rely on microfossil zonations developed by groups from the Royal Netherlands Institute for Sea Research and the Woods Hole Oceanographic Institution.

Paleoclimate and Environmental Changes

The epoch began with extreme greenhouse conditions documented by isotopic studies from teams at Scripps Institution of Oceanography and the Max Planck Institute for Chemistry, then progressed through a long-term cooling trend culminating in Antarctic glaciation recorded by cores from the Deep Sea Drilling Project and the Ocean Drilling Program. Climatic events such as the Paleocene–Eocene Thermal Maximum and later hyperthermal excursions were characterized using proxies refined by researchers at Lamont–Doherty Earth Observatory, ETH Zurich, and Columbia University. Changes in ocean circulation linked to tectonic reconfigurations influenced productivity patterns studied by investigators at National Oceanography Centre and GEOMAR Helmholtz Centre for Ocean Research Kiel.

Flora and Fauna

Terrestrial plant assemblages shifted from tropical floras documented in Fossil Forests of Greenland and Antarctica to the emergence of modern angiosperm-dominated forests described in collections at Kew Gardens and Harvard University Herbaria. Mammalian diversification produced early members of Primates, Perissodactyla, Artiodactyla, and Carnivora preserved in faunas curated by the Natural History Museum of Los Angeles County and the Smithsonian Institution National Museum of Natural History. Marine faunas recorded in deposits studied by the Monterey Bay Aquarium Research Institute included radiation of Cetacea and turnover among Foraminifera documented by paleontologists at University of Cambridge and University of Oxford.

Tectonics and Paleogeography

Plate motions reconstructed by teams from Caltech and the United States Geological Survey show progressive closing of proto-ocean gateways and collision events such as the India–Asia convergence leading to early uplift of the Himalayas studied by researchers at the Indian Institute of Science and Peking University. Rift basins and volcanic arcs influenced sedimentation in basins explored by the Norwegian Petroleum Directorate and the TotalEnergies research groups, while paleogeographic maps developed by scholars at Paleomap Project and University of Texas at Austin illustrate continental positions that affected climate and biotic dispersal involving Australia, South America, and Africa.

Major Events and Extinctions

Notable events include the aftermath of the Paleocene–Eocene Thermal Maximum, multiple hyperthermal pulses identified by teams at University of Bristol and University of Copenhagen, and the terminal cooling and extinction pulse near the Eocene–Oligocene transition documented by collaborators at the Borehole Research Group and the International Ocean Discovery Program. These episodes correspond with turnover in insect, plant, and vertebrate assemblages curated by museums such as the Royal Ontario Museum and studied in paleoecological syntheses from the American Geophysical Union.

Category:Geologic epochs