Eocene first appearances

Brontotheriidae (or Titanotheriidae), is a family of extinct mammals belonging to the order Perissodactyla, the order that includes horses, rhinoceroses, and tapirs from the Eocene epoch. Brontotheres had a Holarctic distribution, with the exception of Western Europe: their fossils have been found in North America and Asia, with a few also known from Eastern Europe. In larger and often better-known genera of the group, a paired or battering-ram-like horn was present on the snout above the eye socket, made of bone, unlike the horns of rhinoceroses. However, this feature is not present in all me

Formica is a genus of ants of the subfamily Formicinae, including species commonly known as wood ants, mound ants, thatching ants, and field ants. Formica is the type genus of the Formicidae, and of the subfamily Formicinae. The type species of genus Formica is the European red wood ant Formica rufa. Ants of this genus tend to be between 4 and 8 mm long.

Amphicyonidae is an extinct family of terrestrial carnivorans belonging to the suborder Caniformia. They first appeared in North America in the middle Eocene (around 45 Ma), spread to Europe by the late Eocene (35 Ma), and further spread to Asia and Africa by the early Miocene (23 Ma). They had largely disappeared worldwide by the late Miocene (9-7 Ma), with the latest recorded species at the end of the Miocene in Africa. They were among the first carnivorans to evolve large body size. Amphicyonids are colloquially referred to as "bear-dogs".

Entelodontidae is an extinct family of pig-like artiodactyls (even-toed ungulates) that inhabited the Northern Hemisphere (Asia, Europe, and North America) from the late Eocene to the early Miocene epochs, about 38 to 15 million years ago. Their large heads, low snouts, narrow gait, and proposed omnivorous diet inspires comparisons to suids (true pigs) and tayassuids (peccaries), and historically they have been considered closely related to these families purely on a morphological basis. However, studies which combine morphological and molecular (genetic) data on artiodactyls instead suggest t

Chalicotheriidae (from Ancient Greek χάλιξ (khálix), meaning "gravel", and θηρίον (theríon), meaning "beast") is an extinct family of herbivorous, perissodactyl mammals. Unlike living odd-toed ungulates, chalicotheriids bore large claws rather than hooves, although their dentition was adapted for browsing. The family is known from the Oligocene to the Pleistocene, reached its greatest diversity in the Miocene, and is known from Asia, Europe, Africa and North America. Asia appears to have been the main centre of diversification for the group.

Anthracotheriidae is a paraphyletic family of extinct, hippopotamus-like artiodactyl ungulates related to hippopotamuses and whales. The oldest genus, Elomeryx, first appeared during the middle Eocene in Asia. They thrived in Africa and Eurasia, with a few species ultimately entering North America during the Oligocene. They died out in Europe and Africa during the Miocene, possibly due to a combination of climatic changes and competition with other artiodactyls, including pigs and hippopotamuses. The youngest genus, Merycopotamus, died out in Asia during the late Pliocene, possibly for the sam

Pakicetidae ("Pakistani whales") is an extinct family of early whales that lived during the Early Eocene in northern South Asia. Unlike modern cetaceans, they had well-developed limbs and were capable of walking. The species included were fox to wolf-sized.

Palaeotheriidae is an extinct family of herbivorous perissodactyl mammals that inhabited Europe, with less abundant remains also known from Asia, from the mid-Eocene to the early Oligocene. They are classified in Equoidea, along with the living family Equidae (which includes zebras, horses and asses).

The Hyracodontidae are an extinct family of rhinocerotoids endemic to North America, Europe, and Asia during the Eocene through early Oligocene, living from 48.6 to 26.3 million years ago (Mya), existing about .

informal group of mammals (fossil)

Adapiformes is a group of early primates. Adapiforms radiated throughout much of the northern continental mass (now Europe, Asia and North America), reaching as far south as northern Africa and tropical Asia. They existed from the Eocene to the Miocene epoch. Some adapiforms resembled living lemurs.

Ambulocetidae is a family of early cetaceans from northern South Asia. The genus Ambulocetus, after which the family is named, is by far the most complete and well-known ambulocetid genus due to the excavation of an 80% complete specimen of Ambulocetus natans. The other two genera in the family, Gandakasia and Himalayacetus, are known only from teeth and mandibular fragments. Retaining large hindlimbs, it was once thought that they could walk on land—indeed, their name means "walking whales"—, but recent research suggests they may have been fully aquatic like modern cetaceans, though the resea

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.

thumb| Tooth paratype of Cadurcotherium nouleti – [[MHNT]] thumb|Zaisanamynodon protheroi

Remingtonocetidae is a diverse family of early aquatic mammals of the order Cetacea. The family is named after paleocetologist Remington Kellogg.

Protocetidae, the protocetids, form a paraphyletic, diverse and heterogeneous group of extinct cetaceans known from Asia, Europe, Africa, South America, and North America.

Adapidae is a family of extinct primates that primarily radiated during the Eocene epoch between about 55 and 34 million years ago.

Raoellidae () is a family of extinct semiaquatic artiodactyls from the middle Eocene (early Lutetian) closely related to cetaceans. They are known primarily from northern India and Pakistan, especially in the Subathu Group of India, although potential remains of the raoellid Khirtharia have been found in northern China. They are relatively small animals; on average, raoellids were the size of a red fox. However, Khirtharia major, at about twice the size of an average-sized raoellid, would have been approximately the size of a coyote. Meanwhile, the smallest raoellid, Metkatius, was roughly the

Arsinoitheriidae is a family of mammals belonging to the extinct order Embrithopoda. Remains have been found in the Middle East, Africa, Asia and Romania. Arsinotheriids were closely related to hyraxes, elephants, sirenians, and possibly desmostylians (as part of the superorder Afrotheria). The name of the clade honors the wife of Ptolemy II, Queen Arsinoe II of Egypt, as the first fossils of Arsinoitherium were found near the ruins of her palace.

The extinct Hesperocyoninae are one of three subfamilies found within the canid family. The other two canid subfamilies are the extinct Borophaginae and extant Caninae.

thumb|Pezosiren portelli cast skeleton Prorastomidae is a family of extinct sirenians from Jamaica, related to the extant manatees and dugong. The family includes the oldest known fossils of Sirenians, represented in two genera: Pezosiren Pezosiren comprises one known species, Pezosiren portelli, that was discovered in modern-day Jamaica. One of the earliest true Sirenian species, P. portelli is distinct from extant Sirenians due to its quadrupedal stature. The species is estimated to have lived 50 million years ago during the Mid Eocene, and the skeletal elements suggest that P. portelli was

Borhyaenidae is an extinct metatherian family of low-slung, heavily built predatory mammals in the order Sparassodonta. Borhyaenids are not true marsupials, but members of a sister taxon, Sparassodonta. Like most metatherians, borhyaenids and other sparassodonts are thought to have had a pouch to carry their offspring around. Borhyaenids had strong and powerful jaws, like those of the unrelated placentalians Hyaenodon and Andrewsarchus, for crushing bones. Borhyaenids grew up to an average of long.

Paraceratheriidae is an extinct family of long-limbed, hornless rhinocerotoids, native to Asia and Eastern Europe that originated in the Eocene epoch and lived until the beginning of the Miocene. They represent some of the largest terrestrial mammals to have ever lived.

Ancylopoda is a group of browsing, herbivorous, mammals in the Perissodactyla that show long, curved and cleft claws. Morphological evidence indicates the Ancylopoda diverged from the tapirs, rhinoceroses and horses (Euperissodactyla) after the Brontotheria; however, earlier authorities such as Osborn sometimes considered the Ancylopoda to be outside Perissodactyla or, as was popular more recently, to be related to Brontotheriidae.

Formiciinae is an extinct subfamily of ants known from Eocene deposits in Europe and North America.

Astrapotheriidae is an extinct family of herbivorous South American land mammals that lived from the Late Eocene (Mustersan SALMA) to the Middle Miocene (Laventan SALMA) . The most derived of the astrapotherians, they were also the largest and most specialized mammals in the Tertiary of South America. There are two sister taxa: Eoastrapostylopidae and Trigonostylopidae.

Notharctidae is an extinct family of adapiform primates found primarily in North America and Europe.

Eomyidae is a family of extinct rodents from North America and Eurasia related to modern day pocket gophers and kangaroo rats. They are known from the Middle Eocene to the Late Miocene in North America and from the Late Eocene to the Pleistocene in Eurasia. Eomyids were generally small, but occasionally large, and tended to be squirrel-like in form and habits. The family includes the earliest known gliding rodent, Eomys quercyi.

Anchitheriinae is an extinct subfamily of the horse family Equidae. The group is suggested to be paraphyletic as a whole, representing various early offshoots of the lineage leading to Equinae (which contains modern zebras, horses and asses), though the tribe Anchitheriini (Anchitheriinae sensu stricto,” or “anchitherines”) represents a monophyletic group. The group first appeared in North America during the late Eocene, around 40 million years ago, subsequently radiating and reaching a peak of diversity by the end of the Eocene, around 34 million years ago, underdoing a slight decline during

Eosimiidae is the possible family of extinct primates believed to be the earliest simians.

Stenoplesictidae is the name of a polyphyletic family of extinct civet-like feliforms.

thumb|right|Skull of Anoplotherium|Anoplotherium commune, showing the unspecified dentition

Leontiniidae is an extinct family comprising eighteen genera of notoungulate mammals known from the Middle Eocene (Mustersan) to Late Miocene (Huayquerian) of South America.

Dichobunidae is an extinct family of basal artiodactyl mammals from the early Eocene to late Oligocene of North America, Europe, and Asia. The Dichobunidae include some of the earliest known artiodactyls, such as Diacodexis.

Proborhyaenidae is an extinct family of metatherian mammals of the order Sparassodonta, which lived in South America from the Eocene (Mustersan) until the Oligocene (Deseadan). Sometimes it has been included as a subfamily of their relatives, the borhyaenids (as Proborhyaeninae). The largest species, Proborhyaena gigantea, is estimated to be about the size of a spectacled bear, with its skull reaching in length, and body mass estimates up to approximately , making the proborhyaenids some of the largest known metatherians. Proborhyaenid remains have been found in western Bolivia, Uruguay, south

Notostylopidae is an extinct family comprising five genera of notoungulate mammals known from the Late Paleocene (Riochican) to Early Oligocene (Tinguirirican) of Argentina, Brazil and Chile in South America

Sivaladapidae is an extinct family of adapiform primates from Asia. They survived longer than any other adapiform primate because they were able to shift south as the climate cooled. Their remains date from the Eocene through the Miocene.

Notohippidae is a paraphyletic extinct family of notoungulate mammals from South America. Notohippids are known from the Eocene and Oligocene epochs.

Oromerycidae is a small (both in size and diversity), extinct family of artiodactyls (even-toed hoofed mammals) closely related to living camels, known from the early to late Eocene of western North America.

Hypertragulidae is an extinct family of Paleogene ruminants endemic to North America from the Eocene until the Oligocene.

Asterostomatidae is an extinct family of sea urchins belonging to the order Spatangoida.

Ptolemaiida is a taxon of wolf-sized afrothere mammals that lived in northern and eastern Africa during the Paleogene. The oldest fossils are from the latest Eocene strata of the Jebel Qatrani Formation, near the Fayum oasis in Egypt. A tooth is known from an Oligocene-aged stratum in Angola, and Miocene specimens (of Kelba) are known from Kenya and Uganda.

Cercamoniinae is a subfamily within the extinct primate family Notharctidae primarily found in Europe, although a few genera have been found in North America and Africa.

Archaeopithecidae is an extinct family comprising two genera of notoungulate mammals, Teratopithecus and Archaeopithecus, both known from the Eocene of Argentina.

Notharctinae is an extinct subfamily of primates that were common in North America during the early and middle Eocene (55-34 million years ago). The six genera that make up the group (Cantius, Pelycodus, Copelemur, Hesperolemur, Notharctus, and Smilodectes) contain species that are among the most primitive of the adapiform group, which is one of the most primitive groups of primates. The evolutionary history of this subfamily has been comparatively well documented and has been used to argue for evolutionary gradualism. Though it is generally accepted that adapiforms gave rise to modern day lem

Pyrotheriidae (from Ancient Greek πῦρ (pûr), meaning "fire", and θηρίον (theríon), meaning "beast") is the only family in the order Pyrotheria, provided one does not include the Paleocene genus, Carodnia. These extinct, elephant-like ungulates include the genera Baguatherium, Carolozittelia, Griphodon, Propyrotherium, and Pyrotherium. Fossils of the family have been found in Argentina, Brazil, Bolivia and Peru.

Parapithecidae is an now extinct family of primates which lived in the Eocene and Oligocene periods in Egypt. Eocene fossils from Myanmar are sometimes included in the family in addition. They showed certain similarities in dentition to Condylarthra, but had short faces and jaws shaped like those of tarsiers. They are part of the superfamily Parapithecoidea, perhaps equally related to Ceboidea and Cercopithecoidea plus Hominoidea - but the placement of Parapithecoidea is substantially uncertain.

Merycoidodontoidea, previously known as "oreodonts" or "ruminating hogs," are an extinct superfamily of prehistoric cud-chewing artiodactyls with short faces and fang-like canine teeth. As their name implies, some of the better known forms were generally hog-like, and the group has traditionally been placed within the Suina (pigs, peccaries and their ancestors), though some recent work suggests they may have been more closely related to camels. "Oreodont" means "mountain teeth," referring to the appearance of the molars. Most merycoidodontoids were sheep-sized, though some genera grew to the s

Oligopithecidae is an extinct basal Catarrhine family from the late Eocene of Egypt (about 37 million years ago) as sister of the rest of the Catarrhines. Its members were probably insectivorous, due to their simple molars and cusp arrangement.

Basilosaurinae is a subfamily of cetaceans archaeocetes containing two genera: Basilosaurus and Basiloterus. They were characterized by elongated distal thoracic vertebrae, lumbar, and proximal sacrococcygeal. All known members of the subfamily are larger than their relatives of the Dorudontinae subfamily except Cynthiacetus.

Homalodotheriidae is an extinct family comprising four genera of notoungulate mammals known from the Late Eocene (Tinguirirican) through Late Miocene (Chasicoan) of Argentina and Chile in South America.

The Phiomyidae are a family of prehistoric rodents from Africa and Eurasia. A 2011 study placed Gaudeamus in a new family, Gaudeamuridae.

Palaeoamasiidae or Palaeoamasinae is an extinct taxon of embrithopod mammals that have been found in Romania and Anatolia where they lived on the shores of the Tethys Ocean.

extinct family of mammals

The Gelocidae are an extinct family of hornless ruminantia that are estimated to have lived during the Eocene and Oligocene epochs, from 36 MYA to 6 MYA. The family generally includes ruminants with dental traits of both the Tragulina and Pecora, making it a notorious wastebasket taxon with unresolved affinities.

Diamantomyidae is a family of extinct hystricognath rodents from Africa and Asia.

Eutypomyidae is a family of extinct rodents from North America and Eurasia thought to be related to modern beavers.

Philisidae is an extinct family of bats of the suborder Microchiroptera that lived between the Eocene to the Late Miocene in the continent of Africa.

Ancodonta is an infraorder of artiodactyl ungulates including modern hippopotamus and all mammals closer to hippos than to cetaceans (whales). Ancodonts first appeared in the Middle Eocene, with some of the earliest representatives found in fossil deposits in Southeast Asia. Throughout their evolutionary history they have occupied different browsing and grazing niches in North America, Eurasia and Africa. The last continent is notable as they were among the first laurasiatherian mammals to have migrated to Africa from Europe, where they competed with the native afrothere herbivores for the sam

Chalicotherioidea (from Ancient Greek χάλιξ (khálix), meaning "gravel", and θηρίον (theríon), meaning "beast") is an extinct superfamily of clawed perissodactyls (odd-toed ungulates) that lived from the early Eocene to the early Pleistocene subepochs. Based on the fossil record they emerged and thrived largely in Eurasia, although specimens have been found in both Africa and North America. They were likely browsers that fed mainly on leaves, twigs, and other nonresistant vegetation. Many of the contained genera had derived specializations of the forelimb and manus that allowed the claws to be