Ungulates are members of the diverse clade Euungulata, which primarily consists of large mammals with hooves. Once part of the clade "Ungulata" along with the clade Paenungulata, "Ungulata" has since been determined to be a polyphyletic and thereby invalid clade based on molecular data. As a result, true ungulates had since been reclassified to the newer clade Euungulata in 2001 within the clade Laurasiatheria while Paenungulata has been reclassified to a distant clade Afrotheria. Living ungulates are divided into two orders: Perissodactyla including equines, rhinoceroses, and tapirs; and Artiodactyla including cattle, antelope, pigs, giraffes, camels, sheep, deer, and hippopotamuses, among others. Cetaceans such as whales, dolphins, and porpoises are also classified as artiodactyls, although they do not have hooves. Most terrestrial ungulates use the hoofed tips of their toes to support their body weight while standing or moving. Two other orders of ungulates, Notoungulata and Litopterna, both native to South America, became extinct at the end of the Pleistocene, around 12,000 years ago.
Moeritherium is an extinct genus of basal proboscideans from the Eocene of North and West Africa.. It was related to elephants and, more distantly, to sea cows and hyraxes.
Litopterna is an extinct order of South American native ungulates that lived from the Paleocene to the end of the Pleistocene-early Holocene around 63 million-12,000 years ago, and were also present in Antarctica during the Eocene. They represent the second most diverse group of South American ungulates after Notoungulata. It is divided into nine families, with Proterotheriidae and Macraucheniidae being the most diverse and last surviving families.
Sparassodonta is an extinct order of carnivorous metatherian mammals native to South America, related to modern marsupials. They were once considered to be true marsupials, but are now thought to be a separate side branch that split before the last common ancestor of all modern marsupials. A number of these mammalian predators closely resemble placental predators that evolved separately on other continents, and are cited frequently as examples of convergent evolution. They were first described by Florentino Ameghino, from fossils found in the Santa Cruz beds of Patagonia. Sparassodonts were present throughout South America's long period of "splendid isolation" during the Cenozoic; during this time, they shared the niches for large warm-blooded predators with the flightless terror birds. Previously, it was thought that these mammals died out in the face of competition from "more competitive" placental carnivorans during the Pliocene Great American Interchange, but more recent research has showed that sparassodonts died out long before eutherian carnivores arrived in South America. Sparassodonts have been referred to as borhyaenoids by some authors, but currently the term Borhyaenoidea refers to a restricted subgroup of sparassodonts comprising borhyaenids and their close relatives.
Chalicotheriidae is an extinct family of herbivorous, odd-toed ungulate (perissodactyl) mammals that lived in North America, Eurasia, and Africa from the Middle Eocene until the Early Pleistocene, existing from 48.6 to 1.806 mya. They are often called chalicotheres, a term which is also applied to the broader grouping of Chalicotherioidea. They are noted for their unusual morphology compared to other ungulates, such as their elongated clawed forelimbs. They are thought to have been browsers.
Miacis is an extinct genus of placental mammals from clade Carnivoraformes, that lived in North America from the early to middle Eocene.
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 presbyornithid bird from North America during the Paleogene period, between the Late Paleocene and Early Eocene.
Metacheiromys is an extinct genus of placental mammals from extinct paraphyletic subfamily Metacheiromyinae within extinct paraphyletic family Metacheiromyidae in extinct order Palaeanodonta, that lived in North America from the early to middle Eocene.
Icaronycteris is an extinct genus of microchiropteran (echolocating) bat that lived in the early Eocene, approximately 52.2 million years ago, making it the earliest bat genus known from complete skeletons, and the earliest known bat from North America. Multiple exceptionally preserved specimens, among the best preserved bat fossils, are known from the Green River Formation of North America. The best known species is I. index. Fragmentary material from France has also been tentatively placed within Icaronycteris as the second species I. menui. I. sigei is based on well-preserved fragments of dentaries and lower teeth found in Western India. In 2023, the species I. gunnelli also from the Green River Formation was distinguished from I. index, and I. menui and I. sigei were proposed to be removed from the genus due to them not being closely related.
Protocetus atavus is an extinct species of primitive cetacean from Egypt. It lived during the middle Eocene period 45 million years ago. The first discovered protocetid, Protocetus atavus was described by Fraas 1904 based on a cranium and a number of associated vertebrae and ribs found in middle Lutetian Tethyan marine limestone from Gebel Mokattam near Cairo, Egypt.
Chriacus is an extinct genus of placental mammals that lived in what is now North America during the Paleocene epoch and died out after the early Eocene. In life, members of the genus would have looked something like a kinkajou or binturong, though they were not closely related to any living mammal. Well preserved fossils allow clear information on what they looked like. They were about 1 metre (3.3 ft) long including a long, robust tail, which may or may not have been prehensile. Other features include a light build, weighing approximately 7 kg (15 lb), and many adaptations typical of animals that live in trees. These include walking on the soles of their five-toed feet, and having long, curved, compressed claws. The powerfully built limbs had flexible joints, especially the ankles, an adaptation that allows an animal to turn its hind feet behind it, like modern tree squirrels, in order to climb downward. They were probably omnivores, eating fruit, eggs, insects and small mammals.
Diacodexis is an extinct genus of small herbivorous mammals belonging to the family Diacodexeidae that lived in North America, Europe and Pakistan from 55.4 mya to 46.2 mya and existing for approximately 9.2 million years.
Oxyaena is an extinct genus of placental mammals from extinct subfamily Oxyaeninae within extinct family Oxyaenidae, that lived in Europe, Asia and North America during the early Eocene.
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.
Teilhardina was an early marmoset-like primate that lived in Europe, North America and Asia during the Early Eocene epoch, about 56-47 million years ago. The paleontologist George Gaylord Simpson is credited with naming it after the French paleontologist, Jesuit and philosopher Teilhard de Chardin.
Amynodontidae is a family of extinct perissodactyls related to true rhinoceroses. They are commonly portrayed as semiaquatic hippo-like rhinos but this description only fits members of the Metamynodontini; other groups of amynodonts like the cadurcodontines had more typical ungulate proportions and convergently evolved a tapir-like proboscis.
Dollosuchus is an extinct monospecific genus of tomistomine crocodilian originally named as a species of Gavialis. It is a basal form possibly related to Kentisuchus, according to several phylogenetic analyses that have been conducted in recent years, and is the oldest known tomistomine to date. Fossils have been found from Belgium and the United Kingdom. It had large supratemporal fenestrae in relation to its orbits, similar to Kentisuchus and Thecachampsa.
Afrasia djijidae is a fossil primate that lived in Myanmar approximately 37 million years ago, during the late middle Eocene. The only species in the genus Afrasia, it was a small primate, estimated to weigh around 100 grams (3.5 oz). Despite the significant geographic distance between them, Afrasia is thought to be closely related to Afrotarsius, an enigmatic fossil found in Libya and Egypt that dates to 38–39 million years ago. If this relationship is correct, it suggests that early simians dispersed from Asia to Africa during the middle Eocene and would add further support to the hypothesis that the first simians evolved in Asia, not Africa. Neither Afrasia nor Afrotarsius, which together form the family Afrotarsiidae, is considered ancestral to living simians, but they are part of a side branch or stem group known as eosimiiforms. Because they did not give rise to the stem simians that are known from the same deposits in Africa, early Asian simians are thought to have dispersed from Asia to Africa more than once prior to the late middle Eocene. Such dispersals from Asia to Africa also were seen around the same time in other mammalian groups, including hystricognathous rodents and anthracotheres.
Homacodontidae is an extinct family of basal artiodactyl mammals from the early Eocene to late Oligocene of North America, Europe, and Asia.
