The Eocene Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name Eocene comes from the Ancient Greek ἠώς and καινός and refers to the "dawn" of modern ('new') fauna that appeared during the epoch.
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present. As with other older geologic periods, the rock beds that define the epoch are well identified but the exact dates of the start and end of the epoch are slightly uncertain. The name Oligocene was coined in 1854 by the German paleontologist Heinrich Ernst Beyrich from his studies of marine beds in Belgium and Germany. The name comes from the Ancient Greek ὀλίγος and καινός, and refers to the sparsity of extant forms of molluscs. The Oligocene is preceded by the Eocene Epoch and is followed by the Miocene Epoch. The Oligocene is the third and final epoch of the Paleogene Period.
The Paleogene is a geologic period and system that spans 43 million years from the end of the Cretaceous Period 66 million years ago (Mya) to the beginning of the Neogene Period 23.03 Mya. It is the beginning of the Cenozoic Era of the present Phanerozoic Eon. The earlier term Tertiary Period was used to define the span of time now covered by the Paleogene Period and subsequent Neogene Period; despite no longer being recognized as a formal stratigraphic term, "Tertiary" still sometimes remains in informal use. Paleogene is often abbreviated "Pg".
Podocnemididae is a family of pleurodire (side-necked) turtles, once widely distributed. Most of its 20 genera and 30 species are now extinct. Seven of its eight surviving species are native to South America: the genus Peltocephalus, with only one species ; and the genus Podocnemis, with six living species of South American side-necked river turtles. There is also one genus native to Madagascar: Erymnochelys, the Madagascan big-headed turtle, whose single species E. madagascariensis.
The Green River Formation is an Eocene geologic formation that records the sedimentation in a group of intermountain lakes in three basins along the present-day Green River in Colorado, Wyoming, and Utah. The sediments are deposited in very fine layers, a dark layer during the growing season and a light-hue inorganic layer in the dry season. Each pair of layers is called a varve and represents one year. The sediments of the Green River Formation present a continuous record of six million years. The mean thickness of a varve here is 0.18 mm, with a minimum thickness of 0.014 mm and maximum of 9.8 mm.
Archaeoceti, or Zeuglodontes in older literature, is a paraphyletic group of primitive cetaceans that lived from the Early Eocene to the late Oligocene. Representing the earliest cetacean radiation, they include the initial amphibious stages in cetacean evolution, thus are the ancestors of both modern cetacean suborders, Mysticeti and Odontoceti. This initial diversification occurred in the shallow waters that separated India and Asia 53 to 45 mya, resulting in some 30 species adapted to a fully oceanic life. Echolocation and filter-feeding evolved during a second radiation 36 to 35 mya.
Presbyornis is an extinct genus of anseriform bird. It contains two unequivocally accepted species; the well-known P. pervetus and the much lesser-known P. isoni. P. pervetus was approximately the size and shape of a goose, but with longer legs; P. isoni, known from a few bones, was much larger, more than swan-sized. Other fossils, more doubtfully assigned to this genus, are also known.
Anosteira is an extinct genus of carettochelyid turtle from the Eocene to the Oligocene of Asia and North America.
Miocyon is an extinct genus of placental mammals from clade Carnivoraformes, that lived in North America from the early to late Eocene.
Cynthiacetus is an extinct genus of basilosaurid early whale that lived during the Late Eocene Specimens have been found in the southeastern United States and Peru.
Allaeochelys is an extinct genus of Carettochelyid turtle, known from the Eocene to Miocene of Europe, Asia, North America and Africa.
The Klondike Mountain Formation is an Early Eocene (Ypresian) geological formation located in the northeast central area of Washington state. The formation is comprised of volcanic rocks in the upper unit and volcanic plus lacustrine (lakebed) sedimentation in the lower unit. the formation is named for the type location designated in 1962, Klondike Mountain northeast of Republic, Washington. The formation is a lagerstätte with exceptionally well-preserved plant and insect fossils has been found, along with fossil epithermal hot springs.
Kala Chitta Range is a mountain range in the Attock District of Punjab, Pakistan. Kala- Chitta are Punjabi words meaning Kala the Black and Chitta means white. The range thrusts eastward across the Potohar plateau towards Rawalpindi.
The Allenby formation is a sedimentary rock formation in British Columbia which was deposited during the Ypresian stage of the Early Eocene. It consists of conglomerates, sandstones with interbedded shales and coal. The shales contain an abundance of insect, fish and plant fossils known from 1877 and onward, while the Princeton Chert was first indented in the 1950's and is known from anatomically preserved plants.
The Willwood Formation is a sedimentary sequence deposited during the late Paleocene to early Eocene, or Clarkforkian, Wasatchian and Bridgerian in the NALMA classification.
The Washakie Formation is a geologic formation in northern Colorado and southern Wyoming. It preserves many mammal, bird, reptile and other fossils dating back to the Lutetian stage of the Eocene within the Paleogene period. The sediments fall in the Bridgerian and Uintan stages of the NALMA classification.
The San Jose Formation is an Early Eocene geologic formation in the San Juan Basin of New Mexico and Colorado.
Viverravus is an extinct genus of placental mammals from extinct subfamily Viverravinae within extinct family Viverravidae, that lived in North America, Europe and Asia from the middle Paleocene to middle Eocene.
The Eocene Okanagan Highlands or Eocene Okanogan Highlands are a series of Early Eocene geological formations which span a 1,000 km (620 mi) transect of British Columbia, Canada, and Washington state, United States. Known for a highly diverse and detailed plant and animal paleobiota the paleolake beds as a whole are considered one of the great Canadian Lagerstätten. The paleobiota represented are of an upland subtropical to temperate ecosystem series immediately after the Paleocene–Eocene thermal maximum, and before the increased cooling of the middle and late Eocene to Oligocene. The fossiliferous deposits of the region were noted as early as 1873, with small amounts of systematic work happening in the 1870–1920s on British Columbian sites, and 1920–1930s for Washington sites. Focus and more detailed descriptive work on the Okanagan Highland sites started in the late 1960s.
Isotemnus is an extinct genus of notoungulate belonging to the family Isotemnidae. It lived from the Late Paleocene to the Middle Eocene of what is now Argentina.
