The Miocene is the first geological epoch of the Neogene Period and extends from about 23.03 to 5.333 million years ago (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words μείων and καινός and means "less recent" because it has 18% fewer modern marine invertebrates than the Pliocene has. The Miocene is preceded by the Oligocene and is followed by the Pliocene.
The Neogene is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period 23.03 million years ago (Mya) to the beginning of the present Quaternary Period 2.58 million years ago. The Neogene is sub-divided into two epochs, the earlier Miocene and the later Pliocene. Some geologists assert that the Neogene cannot be clearly delineated from the modern geological period, the Quaternary. The term "Neogene" was coined in 1853 by the Austrian palaeontologist Moritz Hörnes (1815–1868). The earlier term Tertiary Period was used to define the span of time now covered by Paleogene and Neogene and, despite no longer being recognized as a formal stratigraphic term, "Tertiary" still sometimes remains in informal use.
Lipotidae is a family of river dolphins containing the possibly extinct baiji of China and the fossil genus Parapontoporia from the Late Miocene and Pliocene of the Pacific coast of North America. The genus Prolipotes, which is based on a mandible fragment from Neogene coastal deposits in Guangxi, China, has been classified as an extinct relative of the baiji, but is dubious. The oldest known member of the family is Eolipotes from the Late Miocene of Japan.
Podocnemididae is a family of pleurodire (side-necked) turtles, once widely distributed. Most of its 41 genera and 57 species are now extinct. Seven of its eight surviving species are native to South America: the genus Peltocephalus, with two species, only one of which is extant ; and the genus Podocnemis, with six living species of South American side-necked river turtles and four extinct. There is also one genus native to Madagascar: Erymnochelys, the Madagascan big-headed turtle, whose single species E. madagascariensis.
Kentriodon is an extinct genus of toothed whale related to modern-day dolphins. Fossils have been found in North America, Europe and Japan. Several species have been described.
Kentriodontidae is an extinct family of odontocete whales related to modern dolphins. The Kentriodontidae lived from the Oligocene to the Pliocene before going extinct.
Delphinoidea is the largest group of toothed whales, including 66 genera in 6 families. The largest living member of the superfamily is the killer whale, which can reach 6 tons, while the smallest is the vaquita.
Xenastrapotherium is an extinct genus of astrapothere, a type of hoofed herbivorous mammal, native to South America, which lived in the Middle to Late Miocene period, typically during the Laventan stage. It is a member of the family Astrapotheriidae in the subfamily Uruguaytheriinae, large astrapotheres, equipped with a trunk-like nose and protruding teeth, similar to the elephants, but their tusks were the canine teeth, not the incisors. Xenastrapotherium was a genus widely distributed in northern South America, in contrast to other species of astrapotheres which lived in the area of the Southern Cone of the continent. It differed from other astrapotheres by having two lower incisors on each side of the jaw and the tusks have a pronounced longitudinal curvature, although their general shape and size are probably very similar to Astrapotherium, whose weight would be 900 to 1,500 kilograms, comparable to the current black rhinoceros.
The Astoria Formation is a geologic formation in Washington state & Oregon. It preserves fossils dating back to the early to middle Miocene.
Hilarcotherium is an extinct genus of astrapotheriid mammals that lived in South America during the Middle Miocene (Laventan). The type species is H. castanedaii, found in sediments of the La Victoria Formation, part of the Honda Group in the department of Tolima in Colombia. In 2018, Carrillo et al. described a partial skull and mandible of a second species H. miyou from the Castilletes Formation in the Cocinetas Basin of northern Colombia, and estimated the body weight of the animal at 6,465 kilograms (14,253
Eionaletherium is an extinct genus of ground sloth from the Late Miocene coasts of Venezuela containing one species: E. tanycnemius.
Atocetus is an extinct genus of pontoporiid dolphin found in Miocene-age marine deposits in Peru and California.
Albireonidae is a monotypic group of extinct porpoise-like whales containing the single genus Albireo. These medium-sized, fossil dolphins are very rare and known only from temperate latitudes around the margin of the eastern North Pacific Ocean.
Macrokentriodon is an extinct genus of giant dolphin once assigned to the paraphyletic/polyphyletic family Kentriodontidae. Remains have been found in the late Miocene (Serravallian) Choptank Formation of United States.
Liolithax is an extinct genus of dolphin from the Middle Miocene (Serravallian) Temblor Formation of California.
Lophocetus is an extinct genus of dolphin belonging to the clade Delphinida that is known from late Miocene (Tortonian) marine deposits in California and Maryland. Although usually placed in Kentriodontidae, recent studies have found it only distantly related to Kentriodon.
Hadrodelphis is an extinct genus of dolphin once assigned to the paraphyletic/polyphyletic family Kentriodontidae. Remains have been found in the middle Miocene (Langhian) Calvert Formation of United States.
Tagicetus is an extinct genus of dolphin belonging to the polyphyletic family Kentriodontidae.
The Gaiman Formation, in older literature also referred to as Patagonian Marine Formation, is a fossiliferous geologic formation of the Peninsula Valdés Basin in the eastern Chubut Province of northwestern Patagonia, eastern Argentina.
