Monotypic prehistoric placental genera

Hyracotherium ( ; "hyrax-like beast") is an extinct genus of small (about 60 cm in length) perissodactyl ungulates that was found in the London Clay formation. This small, fox-sized animal is (for some scientists) considered to be the earliest known member of Equidae before the type species, H. leporinum, was reclassified as a palaeothere, a perissodactyl family related to both horses and brontotheres. The remaining species are now thought to belong to different genera, such as Eohippus, which had previously been synonymised with Hyracotherium.

Prorastomus sirenoides is an extinct species of primitive sirenian that lived during the Eocene Epoch 40 million years ago in Jamaica.

Phosphatherium escuilliei, named by Gheerbrant, Sudre and Cappetta in 1996, is a basal proboscidean that lived in Africa during the Early Eocene, about 56-55 Ma. It is one of the earliest known proboscideans, together with Eritherium azzouzorum from the Selandian (about 60 Ma). It was found in phosphorites beds from the base of the Ypresian stage of the Ouled Abdoun Basin, which is best known for its exceptionally rich marine vertebrate fauna.

Simbakubwa ("great lion" in Swahili) is an extinct genus of hyaenodonts belonging to the family Hyainailouridae that lived in Kenya during the Early Miocene. It was discovered between 1978 and 1981 near Meswa Bridge in western Kenya, and its remains, consisting of a lower jaw, part of the snout, and some of the smaller limb bones, were originally believed to come from hyena. After re-examination by Matthew Borths and Nancy Stevens, it was named and assigned to the hyaenodont lineage in 2019. One species of Simbakubwa, S. kutokaafrika, has been described.

Amebelodon is a genus of extinct proboscidean belonging to Amebelodontidae (the so-called shovel-tuskers). The most striking attribute of this animal is its lower tusks, which are narrow, elongated, and distinctly flattened with the degree of flattening varying among the different species. One valid species is known for this genus, which was endemic to North America. Other species once assigned to Amebelodon are now assigned to the genus Konobelodon, which was once a subgenus.

Onychonycteris was the more primitive of the three oldest bats known from complete skeletons, having lived in the area that is current day Wyoming during the Eocene period, 52.5 million years ago.

Eritherium is an extinct genus of early Proboscidea found in the Ouled Abdoun basin (early Thanetian age), Morocco. It lived about 60 million years ago. It was first named by Emmanuel Gheerbrant in 2009 and the type species is Eritherium azzouzorum. Eritherium is the oldest, smallest and most primitive known elephant relative.

Iranotherium ("Beast of Iran") is an extinct genus of large elasmotheriine rhinocerotids, comparable in size to a modern white rhino. It is known from the Late Miocene (Tortonian) of Maragha, Iran and the middle part of the Liushu formation of northwestern China. It was a precursor to the related Sinotherium and may have been ultimately outcompeted by its descendant. This species is most well known for showing unique sexual dimorphism among rhinos.

Ankalagon is an extinct genus of carnivorous mammal of the family Mesonychidae, endemic to North America during the Paleocene epoch (63.3—60.2 mya), existing for approximately . There is only one known species: the type species Ankalagon saurognathus. Discovered in the Nacimiento Formation of New Mexico, Ankalagon is the largest mesonychid known from the Paleocene of North America and it provides the best evidence for sexual dimorphism in the group.

thumb|right|Restoration thumb|↑Pholidocercus hassiacus von Koenigswald and Storch 1983 with partially preserved fur and long, thick, scaled tail. Paratype of the publication

Alcidedorbignya is an extinct pantodont mammal known from the Early Paleocene (Tiupampan SALMA, ) Santa Lucia Formation (, paleocoordinates ) at Tiupampa near Mizque, Cochabamba, Bolivia.

Abdounodus ("Abdoun tooth") is an extinct genus of mammal known from the middle Paleocene of Northern Africa. The sole species, A. hamdii, is known from teeth and jaw bones discovered in the Ouled Abdoun Basin of present-day Morocco in 2001.

Anagale is an extinct genus of mammal from the Early Oligocene of Mongolia. Its closest living relatives are the rodents and lagomorphs.

Kalimantsia is an extinct chalicothere from the Miocene of Bulgaria, Europe. It contains one species, Kalimantsia bulgarica.

Bastetodon (meaning "Bastet tooth") is an extinct genus of carnivorous hyaenodont mammal from the Early Oligocene Jebel Qatrani Formation of Egypt. The genus contains single species, B. syrtos, which was originally assigned to the genus Pterodon. It was a medium-sized hyaenodont, with an estimated body mass ranging around .

Vulcanops jennyworthyae is an extinct species of bat that lived during the Miocene in New Zealand, a large burrowing microchiropteran that probably ate arthropods and plant material around twenty million years before present. It is the type and only described species of the genus Vulcanops.

Palaeomyrmidon is an extinct genus of anteater. Its closest living relative is the silky anteater (Cyclopes didactylus). Although the silky anteater is arboreal, Palaeomyrmidon lived on the ground. Palaeomyrmidon is known from a fossil skull that was found in the Andalhualá Formation of Argentina.

genus of mammals (fossil)

Ahytherium is an extinct genus of megalonychid sloth that lived during the Pleistocene of what is now Brazil. It is a monotypic genus that contains a single species, A. aureum. == Discovery and taxonomy == The almost-complete skeleton of Ahytherium alongside remains of another extinct sloth species, Australonyx, were discovered in Poço Azul, an underwater cave in Chapada Diamantina National Park in 2005. It was described by Castor Cartelle of Pontifícia Universidade Católica de Minas Gerais. The bones, which had a length of about when put together, belong to an animal which presumably was stil

Maocyon ("dog from Maoming") is an extinct genus of hyaenodonts from extinct paraphyletic subfamily Hyainailourinae within paraphyletic family Hyainailouridae, that lived during the late Eocene in China. It is a monotypic genus that contains the species M. peregrinus.

Messelogale ("weasel from Messel") is an extinct genus of placental mammals from clade Carnivoraformes, that lived in Europe during the middle Eocene.

Antarctodon is an extinct genus of mammals from the Early Eocene (late Ypresian age). It is a basal astrapotherian which lived in what is now Seymour Island, Antarctic Peninsula, at that moment still connected to South America where most of the astrapotherians were found. The holotype and only specimen MLP 08-XI-30-1, an isolated right p4 or m1, was found in the Telm 5 Member of the La Meseta Formation in West Antarctica. It was first named by Mariano Bond, Alejandro Kramarz, Ross D. E. MacPhee and Marcelo Reguero in 2011 and the type species is Antarctodon sobrali.

Anomotherium is an extinct genus of manatee that lived in the shallow seas of what is now Northern Germany. Its closest relative is Miosiren. Fossils of the genus have been found in the Bohlen and Doberg Formations of Germany.

Aztlanolagus is an extinct monotypic genus of rabbit that lived during the Quaternary in what is now the Southern to Southwestern United States and northern Mexico. Aztlanolagus agilis is currently the only recognized species, though differences among recovered fossils suggest that there may have been other species. The generic name refers to Aztlán, the legendary place of origin of the Nahua peoples as recorded in the mythological accounts of the Aztecs and other Nahua groups. By some traditions, this legendary locale is placed in the border regions of the Southwestern United States and adjac

Gigantohyrax was a genus of herbivorous hyrax-grouped mammals from the Pliocene Shungura Formation of Ethiopia. Fossils have also been found in Makapansgat of South Africa.

Mlanyama ("carnivore") is an extinct genus of hyainailourid hyaenodont mammal of the subfamily Hyainailourinae, that lived from the Late Oligocene to early Miocene in northwestern Kenya (found at Benson's Site).

Preregidens ("frontal royal tooth") is an extinct genus of placental mammals from extinct family Hyaenodontidae, found in what is now France. It lived during the early Eocene epoch (Ypresian stage). It is a monotypic genus that contains the species P. langebadrae.

Allalmeia was a small notoungulate mammal of around 3 kilograms. It lived in Mendoza Province, Argentina (Divisadero Largo Formation) during the Late Eocene. Allalmeia belonged to the Oldfieldthomasiidae family within the suborder Typotheria.

Boritia ("animal from La Borie") is an extinct genus of placental mammals from extinct family Hyaenodontidae, that lived in France during the early Eocene epoch (Ypresian stage). It is a monotypic genus that contains the species B. duffaudi.

Archaeopithecus is an extinct genus of notoungulate, belonging to the suborder Typotheria. It lived during the Middle Eocene, in what is today Argentina.

Ravenictis is an extinct monotypic genus of mammal that lived in the early Puercan, during the Danian stage of the Palaeocene epoch.

Boualitomus ("Bou Ali cutter") is an extinct genus of placental mammals from extinct paraphyletic clade Boualitominae within extinct order Hyaenodonta, that lived in what is now Morocco during the earliest Eocene.

Aegyptonycteris ("Egyptian bat") is a genus of extinct bat from the Late Eocene of North Africa. It is currently known from a single specimen (holotype CGM 83740) from the Birket Qarun Formation in the Fayum Depression in western Egypt.

Arcanotherium is an extinct genus of early proboscidean belonging to the family Numidotheriidae that lived in North Africa during the late Eocene/early Oligocene interval.

Blancotherium (meaning "Blanco Creek beast") is an extinct genus of gomphotheriid proboscidean from Texas. Originally named Gnathabelodon "buckneri", the genus consists solely of type species B. buckneri.

Lahimia ("carnivore") is an extinct genus of placental mammals from extinct paraphyletic clade Boualitominae within extinct order Hyaenodonta, known from the middle Paleocene (Selandian stage) of Morocco. Lahimia selloumi is one of the oldest known members of order Hyaenodonta.

genus of mammals (fossil)

Protitanotherium is a genus of brontotheres native to North America during the middle Eocene. It contains one species, P. emarginatum, described in 1895 by the American paleontologist John Bell Hatcher.