Andrewsarchus, meaning "Andrews' ruler", is an extinct genus of artiodactyl that lived during the Middle Eocene in what is now China. The genus was first described by Henry Fairfield Osborn in 1924 with the type species A. mongoliensis based on a largely complete cranium. A second species, A. crassum, was described in 1977 based on teeth. A mandible, formerly described as Paratriisodon, does probably belong to Andrewsarchus as well. The genus has been historically placed in the families Mesonychidae or Arctocyonidae, or was considered to be a close relative of whales. It is now regarded as the sole member of its own family, Andrewsarchidae, and may have been related to entelodonts. Fossils of Andrewsarchus have been recovered from the Middle Eocene Irdin Manha, Lushi, and Dongjun Formations of Inner Mongolia, each dated to the Irdinmanhan Asian land mammal age.
Plesiadapis is one of the oldest known primate-like mammal genera which existed about 58–55 million years ago in North America and Europe. Plesiadapis means "near-Adapis", which is a reference to the adapiform primate of the Eocene period, Adapis. Plesiadapis tricuspidens, the type specimen, is named after the three cusps present on its upper incisors.
Oligopithecus is a fossil primate that lived in Africa during the Early Oligocene. It is represented by one species, Oligopithecus savagei, known from one jaw bone found in Egypt.
Necrolemur is a small bodied omomyid with body mass estimations ranging from 114–346 g (4.0–12.2 oz). Necrolemur’s teeth feature broad basins and blunt cusps, suggesting their diet consisted of mostly soft fruit, though examination of microwear patterns suggests that populations from lower latitudes also consumed insects and gums.
Altanius is a genus of extinct primates found in the early Eocene of Mongolia. Though its phylogenetic relationship is questionable, many have placed it as either a primitive omomyid or as a member of the sister group to both adapoids and omomyids. The genus is represented by one species, Altanius orlovi, estimated to weigh about 10–30 g (0.35–1.1 oz) from relatively well-known and complete dental and facial characteristics.
Bugtilemur is an extinct genus of Strepsirhine primate belonging to the adapiform family Ekgmowechashalidae.It is represented by only one species, B. mathesoni, which was found in the Chitarwata Formation of Pakistan.
Gobicyon is an extinct genus of large-sized carnivoran mammals, belonging to the Amphicyonidae, that was discovered in China, Mongolia, and Serbia, and lived during the Middle Miocene epoch. Despite only being known from rather fragmentary remains, recent discoveries showcase that it was an aberrant member of the subfamily Haplocyoninae, with adaptions towards bone-crushing similar to those of a hyaena.
Duerotherium is an extinct genus of Palaeogene artiodactyls known only from the Iberian Peninsula during the Middle Eocene, which contains one species D. sudrei. It, like other members of the Anoplotheriidae, was endemic to Western Europe. The anoplotheriine was described from a left fragment of a maxilla from the Mazaterón Formation of the Duero Basin in 2009. Its dentition is mostly typical of the Anoplotheriinae but differs by an elongated plus triangular 3rd upper premolar and very specific traits of the molars. It is thought to have been part of an endemic faunal assemblage that evolved within the Iberian Peninsula by the Middle Eocene, where climates were subtropical.
Ekgmowechashala is an extinct genus of primate belonging to Adapiformes.
Cantius is a genus of adapiform primates from the early Eocene of North America and Europe. It is extremely well represented in the fossil record in North America and has been hypothesized to be the direct ancestor of Notharctus in North America. The evolution of Cantius is characterized by a significant increase in body mass that nearly tripled in size. The earliest species were considered small-sized and weighed in around 1 kg (2.2 lb), while the later occurring species were considered medium-sized and likely weighed in around 3 kg (6.6 lb). Though significantly smaller, the fossil remains discovered of the various species of Cantius have striking similarities to that of Notharctus and Smilodectes. It is likely Cantius relied on arboreal quadrupedal locomotion, primarily running and leaping. This locomotor pattern comparable to that of extant lemurs, which has fostered the hypothesis that Cantius and other strepsirrhine adapiforms may have a close phylogenetic affinity to living lemurs.
Dermotherium is a genus of fossil mammals closely related to the living colugos, a small group of gliding mammals from Southeast Asia. Two species are recognized: D. major from the Late Eocene of Thailand, based on a single fragment of the lower jaw, and D. chimaera from the Late Oligocene of Thailand, known from three fragments of the lower jaw and two isolated upper molars. In addition, a single isolated upper molar from the Early Oligocene of Pakistan has been tentatively assigned to D. chimaera. All sites where fossils of Dermotherium have been found were probably forested environments and the fossil species were probably forest dwellers like living colugos, but whether they had the gliding adaptations of the living species is unknown.
Anaptomorphinae is a pre-historic group of primates known from Eocene fossils in North America and Europe and later periods of Paleocene Asia, and are a sub-family of omomyids. The anaptomorphines is a paraphyletic group consisting of the two tribes Trogolemurini and Anaptomorphini. Anaptomorphine radiation in Wyoming, one of the most detailed records of changes within populations and between species in the fossil record, has provided remarkable evidence of transitional fossils.
Djebelemur is an extinct genus of early strepsirrhine primate from the late early or early middle Eocene period from the Chambi locality in Tunisia. Although they probably lacked a toothcomb, a specialized dental structure found in living lemuriforms, they are thought to be a related stem group. The one recognized species, Djebelemur martinezi, was very small, approximately 100 g (3.5 oz).
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.
Indraloris is a fossil primate from the Miocene of India and Pakistan in the family Sivaladapidae. Two species are now recognized: I. himalayensis from Haritalyangar, India and I. kamlialensis from the Pothohar Plateau, Pakistan. Other material from the Potwar Plateau may represent an additional, unnamed species. Body mass estimates range from about 2 kg (4.4 lb) for the smaller I. kamlialensis to over 4 kg (8.8 lb) for the larger I. himalayensis.
Sivaladapis is a genus of adapiform primate that lived in Asia during the middle Miocene.
Muangthanhinius is a genus of adapiform primate that lived in Asia during the late Eocene.
Microsyops is a plesiadapiform primate found in Middle Eocene in North America. It is in the family Microsyopidae, a plesiadapiform family characterized by distinctive lanceolate lower first incisors. It appears to have had a more developed sense of smell than other early primates. It is believed to have eaten fruit, and its fossils show the oldest known dental cavities in a mammal.
Helohyidae were a group of artiodactyl mammals. They were most prominent in the mid-to-upper Eocene.
Laomaki is a genus of adapiform primate that lived during the Early Oligocene in Asia, containing only the species Laomaki yunnanensis. It was described from a right maxilla fragment. Its molars and premolars are somewhat similar to those of Rencunius and Anthradapis respectively. Its placement within the family Sivaladapidae is uncertain; it has not been placed in a subfamily. It has been found at sites in Jammu and Kashmir and Yunnan, having lived around the time of the Eocene–Oligocene transition.
