Eocene genus extinctions

Gastornis is an extinct genus of large, flightless birds that lived during the mid-Paleocene to mid-Eocene epochs of the Paleogene period. Most fossils have been found in Europe, and some species typically referred to the genus are known from North America and Asia. Several genera, including the well-studied genus Diatryma, have historically been considered junior synonyms of Gastornis. However, this interpretation has been challenged recently, and some researchers currently consider Diatryma to be a valid genus.

Propalaeotherium was an early genus of perissodactyl endemic to Europe and Asia during the early Eocene. There are currently six recognised species within the genus, with P. isselanum as the type species (named by Georges Cuvier in 1824).

Coryphodon (from Greek , "point", and , "tooth", meaning peaked tooth, referring to "the development of the angles of the ridges into points [on the molars].") is an extinct genus of pantodonts of the family Coryphodontidae.

Oxyaena ("sharp hyena") is an extinct genus of placental mammals from extinct subfamily Oxyaeninae within extinct family Oxyaenidae, that lived in Europe, Asia and North America (with most specimens being found in Colorado) during the early Eocene.

Mesonyx ("middle claw") is an extinct genus of mesonychid, one of the families that is part of the extinct order Mesonychia. Fossils of the various species are found in Early to Late Eocene-age strata in the United States and Early Eocene-aged strata in China, 51.8—51.7 Ma (AEO).

Sarkastodon ("flesh-tearing tooth") is an extinct genus of placental mammals from the extinct subfamily Oxyaeninae within the extinct family Oxyaenidae. The genus lived in Asia (in today's China and Mongolia) during the middle Eocene and was the last known oxyaenid. The first fossil of Sarkastodon, part of a lower jaw, was discovered in 1928 in one of the Central Asiatic Expeditions. The second, consisting of the front of the skull and two partial lower jaws, was discovered by a surgeon, Dr. A. Z. Garber, in the final expedition, two years later. Recognised as a "relatively colossal" oxyaenid,

Machaeroides ("dagger-like") is an extinct genus of sabre-toothed predatory placental mammals from the extinct subfamily Machaeroidinae within the extinct family Oxyaenidae, that lived in North America (Wyoming) from the early to middle Eocene.

Patriofelis ("father of cats") is an extinct genus of carnivorous placental mammals from the extinct subfamily Oxyaeninae within the extinct family Oxyaenidae, which lived from the early to middle Eocene, during the Bridgerian stage of NALMA. The first remains were discovered in 1869 by geologist Ferdinand Vandeveer Hayden, and the genus was named the following year by Joseph Leidy. Over the next few decades, additional specimens would be named from the same locality (or similar ones), many assigned to genera of their own or to separate species within Patriofelis. Now, only two are recognised:

Epihippus is an extinct genus of the modern horse family Equidae that lived in the Eocene, from 46 to 38 million years ago.

Gobiatherium (from Gobi Desert, and Ancient Greek θηρίον (thēríon), meaning "beast") was one of the last uintatheriids, from the Mid Eocene of Mongolia.

Orohippus (from the Greek , 'mountain' and , 'horse') is an extinct equid that lived in the Eocene (about 50 million years ago). Its fossils have been unearthed in Oregon, Colorado, Utah, and Wyoming.

thumb|350x350px|Silicified Gryphaea sp. from the Lower Jurassic. Le Liquier, Aveyron, France. Max Rouger collection. Gryphaea, one of the genera known as '''devil's toenails''', is a genus of extinct oysters, marine bivalve mollusks in the family Gryphaeidae.

Pachyaena (literally, "thick hyena") was a genus of heavily built, relatively short-legged mesonychids. Mesonychids were part of the now extinct order known as Mesonychia, a group mammalian predators that evolved before modern ungulates or carnivorans. Despite this, mesonychians are found to have combined characteristics of both carnivorans and ungulates. The genus likely originated from Asia and dispersed to Europe, and from there to North America across a land bridge in what is now the North Atlantic ocean. Pachyaena would later be replaced by Dissacus in Europe.

Harpagolestes ("hooked thief") is an extinct genus of hyena like, bear sized mesonychid mesonychian that lived in Central and Eastern Asia and western and central North America during the middle to late Eocene. It has been suggested that Harpagolestes is a wastebasket genus for fragmentary Eocene mesonychids.

Palaeonictis ("ancient weasel") is an extinct genus of placental mammals from extinct subfamily Palaeonictinae within extinct family Oxyaenidae, that lived in Europe and North America from the late Paleocene to the early Eocene.

Madtsoia is an extinct genus of madtsoiid snakes. It is known from the Eocene of Argentina (M. bai), the Paleocene of Brazil (M. camposi), the Late Cretaceous (Maastrichtian) of India (M. pisdurensis), and the Late Cretaceous (Maastrichtian) of Madagascar (M. madagascariensis). The type species (M. bai) was the largest with an estimated length of , and the other three species were smaller. A long M. madagascariensis would have weighed , but an isolated specimen suggests that this species reached in maximum length. Juvenile Madtsoia madagascariensis may have eaten a wide array of small vertebra

Glyphea is a genus of fossil glypheoid crustaceans that lived from the Jurassic to the Eocene. It includes the following species:

Cretalamna is a genus of extinct otodontid shark that lived from the latest Early Cretaceous to Eocene epoch (about 103 to 46 million years ago). It is considered by many to be the ancestor of the largest sharks to have ever lived, such as Otodus angustidens, Otodus chubutensis, and Otodus megalodon.

Dissacus is a genus of extinct carnivorous jackal to coyote-sized mammals within the family Mesonychidae, an early group of hoofed mammals that evolved into hunters and omnivores. Their fossils in Paleocene to Early Eocene aged strata in France, Asia and southwest North America, from 66 to 50.3 mya, existed for approximately .

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thumb|left|Restoration of Haplohippus (middle right) and other animals of the Hancock Mammal Quarry Haplohippus is an extinct genus of the modern horse family Equidae, that lived in the Eocene, from 42 to 38 million years ago. Fossil remains of Haplohippus have been found in the Clarno Formation, part of the John Day Fossil Beds National Monument of the Northwestern United States. While Haplohippus is quite similar to Orohippus, it is considered more primitive in character than Epihippus.

Pseudocrypturus is a genus of extinct paleognathous bird. Three species are known and the type species is Pseudocrypturus cercanaxius. It is a relative of such modern birds as ostriches. It lived in the early Eocene. The holotype fossil is in the collection of the Smithsonian's National Museum of Natural History. It has catalog number USNM 336103. It was collected from the Fossil Butte Member, Green River Formation, Lincoln County, Wyoming.

Tylocidaris is an extinct genus of sea urchins that lived from the Early Cretaceous to the Eocene. Its remains have been found in Europe and North America.

Zamites is an extinct genus of plants in the family Williamsoniaceae that lived from the Triassic to the Eocene. This plant is reported in the Mesozoic from North and South America, Europe, Asia, Africa, and Antarctica, and in the Cenozoic only in North America.

Rotularia is an extinct genus of planispirally coiled fossil polychaete worms in the family Serpulidae. Owing to the gastropod-like shape of Rotularia, many authors in the past interpreted this genus as being sea snails in the family Vermetidae. Like many other members from Vermetidae the Rotularia is approximately 5 inches in length. This is an estimate from the 151 confirmed fossil discoveries.

Pliolophus is an extinct equid that lived in the Early Eocene of Britain.

Tytthaena ("little hyena") is an extinct genus of placental mammals from extinct subfamily Tytthaeninae within extinct family Oxyaenidae, that lived in North America from the late Paleocene to early Eocene.

Rhynchonella is an extinct genus of brachiopods known from the Late Jurassic (Oxfordian) to the Early Cretaceous (Valanginian, possibly Barremian). Formerly this genus was understood much more widely (more or less an equivalent of the Rhynchonellida order in the present-day taxonomy) and less critical sources still list species of Rhynchonella from the Ordovician to the Eocene. Like most brachiopods, Rhynchonella was a stationary epifaunal suspension feeder.

Phymosoma is an extinct genus of echinoids that lived from the Cretaceous to the Eocene. Its remains have been found in Asia, Europe, and North America. thumb|left|Syngnathid and Phymosoma granulosum fossils at the Geological Museum in Copenhagen