| Erlianhyus Temporal range: | |
|---|---|
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Artiodactyla |
| Clade: | Cetancodontamorpha |
| Genus: | † Erlianhyus Li & Li, 2021 |
| Type species | |
| Erlianhyus primitivus Li & Li, 2021 | |
Erlianhyus is a genus of cetancodontamorph artiodactyl that lived during the Middle Eocene in China. It is monotypic and known from one species, E. primitivus. [1]
The holotype of Erlianhyus (IVPP V 28275) was discovered in strata from the Irdin Manha Formation. Its binomial name is derived from the Erlian Basin, in which it was discovered, and the suffix -hyus, which is often applied to bunodont artiodactyls. The species name, primitivus, refers to it bearing relatively primitive features. [1] Erlianhyus was originally regarded as the sister taxon of a clade containing dichobunids, anthracotheriids and suoids. [1] In 2023, Yu and colleagues performed a phylogenetic analysis that recovered it in a polytomy with Andrewsarchus and Achaenodon . [2]
Erlianhyus is known from a partial maxilla that preserves teeth P3–M3. The molars are bunodont and bear weak cristae, similar to entelodontids. [1] Similarly M1 in both Erlianhyus and entelodonts lacks lingual cingulum. However, the molars have a large and lingually-positioned metaconule and the postmetaconule crista on M1 and M2 are distinct, suggesting that it does not belong to that clade. [2]
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.
Entelodontidae is an extinct family of pig-like artiodactyls which inhabited the Northern Hemisphere from the late Eocene to the early Miocene epochs, about 38-19 million years ago. Their large heads, low snouts, narrow gait, and proposed omnivorous diet inspires comparisons to suids 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 that entelodonts are cetancodontamorphs, more closely related to hippos and cetaceans through their resemblance to Pakicetus, than to basal pigs like Kubanochoerus and other ungulates.
Archaeotherium is an extinct genus of entelodont artiodactyl endemic to North America during the Eocene and Oligocene epochs. Archaeotherium fossils are most common in the White River Formation of the Great Plains, but they have also been found in the John Day Basin of Oregon and the Trans-Pecos area of Texas. Archaeotherium's fossils come from North America, between the Priabonian and Rupelian stages of the Eocene and Oligocene. Up to fifteen species of Archaeotherium have been identified, which are divided into three subgenera. One contains the type species, A. mortoni, among others; another contains very large taxa formerly named Megachoerus and Pelonax; and the last contains A. calkinsi.
Brachyhyops is an extinct genus of entelodont artiodactyl mammal that lived during the Eocene Epoch of western North America and southeastern Asia. The first fossil remains of Brachyhyops are recorded from the late Eocene deposits of Beaver Divide in central Wyoming and discovered by paleontology crews from the Carnegie Museum of Natural History during the early 20th century. The type species, Brachyhyops wyomingensis, is based on a single skull and was named by E.H. Colbert in 1937, but was not officially described until 1938. During the latter half of the 20th century, additional specimens from North America have been recorded from Saskatchewan and as far south as Texas, indicating that Brachyhyops had a broad distribution and was well-dispersed throughout western North America.
The Irdin Manha Formation is a geological formation from the Eocene located in Inner Mongolia, China, a few kilometres south of the Mongolian border.
Cetancodontamorpha is a total clade of artiodactyls defined, according to Spaulding et al., as Whippomorpha "plus all extinct taxa more closely related to extant members of Whippomorpha than to any other living species". Attempts have been made to rename the clade Whippomorpha to Cetancodonta, but the former maintains precedent.
Duerotherium is an extinct genus of artiodactyl that lived during the Middle Eocene and is only known from the Iberian Peninsula. The genus is a member of the family Anoplotheriidae and the subfamily Anoplotheriinae, and contains one species, D. sudrei. Like other anoplotheriids, it was endemic to Western Europe. The genus was described based on a left fragment of a maxilla from the Mazaterón Formation of the Duero Basin, from which its name derives, in 2009. Its dentition is mostly typical of the Anoplotheriinae but differs from related genera in the elongated and triangular third upper premolar and traits of the molars. It is thought to have been part of an endemic fauna that evolved in the Iberian Peninsula during the Middle Eocene, when climates were subtropical.
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.
Proentelodon is an extinct genus of entelodont artiodactyl from the Middle Eocene of Mongolia. P. minutus is the oldest representative of the family Entelodontidae, P. minutus gen. et sp. nov, is described from the Middle Eocene Khaichin Ula II Fauna in Mongolia. The placement of the genus in the entelodonts has been questioned by other authors, but its placement as related to the group has been supported by some cladistic analyses.
Helohyidae were a group of artiodactyl mammals. They were most prominent in the mid-to-upper Eocene.
Achaenodon is an extinct artiodactyl mammal, possibly belonging to the family Helohyidae. It lived in the mid-late Eocene and its fossil remains have been found in North America.
Dichodon is an extinct genus of Palaeogene artiodactyls belonging to the family Xiphodontidae. It was endemic to Western Europe and lived from the middle Eocene up to the earliest Oligocene. The genus was first erected by the British naturalist Richard Owen in 1848 based on dental remains from the fossil beds in Hordle, England. He noticed similar dentitions to contemporary artiodactyls like those of the Anoplotheriidae and Dichobunidae and references the name of the genus Dichobune. Eventually, it was found to be more closely related to Xiphodon and now includes 11 species, although one of them may be synonymous.
Catodontherium is an extinct genus of Palaeogene artiodactyls belonging to the family Anoplotheriidae. It was endemic to Western Europe and had a temporal range exclusive to the middle Eocene, although its earliest appearance depends on whether C. argentonicum is truly a species of Catodontherium. It was first named Catodus by the French palaeontologist Charles Depéret in 1906, who created two species for the genus and later changed the genus name to Catodontherium in 1908. The Swiss palaeontologist Hans Georg Stehlin renamed one species and classified two other newly erected species to Catodontherium in 1910. Today, there are four known species, although two remain questionable in genus placement.
Ephelcomenus is an extinct genus of Palaeogene artiodactyls endemic to Western Europe. It contains one species E. filholi, which was first described by Richard Lydekker in 1889 but eventually classified to its own genus by the Swiss palaeontologist Johannes Hürzeler in 1938. It has an uncertain stratigraphic range, but some sources suggest that it was present in the Oligocene after the Grande Coupure turnover event of western Europe.
Robiatherium is an extinct genus of Palaeogene artiodactyls containing one species R. cournovense. The genus name derives from the locality of Robiac in France where some of its fossil were described plus the Greek θήρ/therium meaning "beast" or "wild animal". It was known only from the middle Eocene and, like other anoplotheriids, was endemic to Western Europe. The genus was erected by Jean Sudre in 1988 for a species originally attributed to the xiphodont genus Paraxiphodon in 1978. Robiatherium had dentitions typical of the subfamily Anoplotheriinae, differing from other genera by specific differences in the molars. It is one of the earliest-appearing anoplotheriine species in the fossil record as well as the earliest to have appeared in Central Europe.
Mixtotherium is an extinct genus of Palaeogene artiodactyls belonging to the monotypic family Mixtotheriidae. Known informally as mixtotheriids or mixtotheres, these artiodactyls were endemic to western Europe and occurred from the middle to late Eocene. The genus and type species were both first established by the French naturalist Henri Filhol in 1880. Several species are well known by good skull fossils, which were informative enough to allow for classifications of the species to their own family. The Mixtotheriidae, first recognized by Helga Sharpe Pearson in 1927, is currently known by 7 valid species, although M. priscum is thought by several authors to be synonymous with M. gresslyi. The affinities of the Mixtotheriidae in relation to other artiodactyl families is uncertain, but it is currently thought to have been related to the Cainotherioidea and Anoplotheriidae.
Palaeohodites is an extinct genus of primate from the Eocene Nadu Formation of China. Living about 35 million years ago during the late Eocene, Palaeohodites belongs to an extinct group of primates known as adapiforms, related to modern day lemurs and lorises. Specifically, this genus is one member of the family Ekgmowechashalidae, known primarily from the Eocene and Oligocene of Asia. Notably, Palaeohodites has been recovered as the sister taxon of Ekgmowechashala, the latest primate known to exist in North America before the arrival of humans at the end of the Pleistocene.
Haplomeryx is an extinct genus of Palaeogene artiodactyls belonging to the family Xiphodontidae. It was endemic to Western Europe and lived from the middle Eocene up to the earliest Oligocene. Haplomeryx was first established as a genus by the German naturalist Max Schlosser in 1886 based on a molar tooth set from Quercy Phosphorites deposits. Three additional species were erected and classified to the xiphodontid genus while one other species, first recognized in 1822, was tentatively classified to it and remains unresolved in affinity.
Chakpaktas Formation is a geological formation in eastern Kazakstan, as well as being the lowest fossil-bearing strata of the Zaysan Depression. The formation is aged to the Arshantan Asian Land Animal Age which correlates to between the upper Ypresian and lower Lutetian.
Amphimeryx is an extinct genus of Palaeogene artiodactyls belonging to the Amphimerycidae that was endemic to the central region of western Europe and lived from the Late Eocene to the Early Oligocene. It was erected in 1848 by the French palaeontologist Auguste Pomel, who argued that its dentition was roughly similar to those of ruminants. Hence, the etymology of the genus name means "near ruminant," of which it derives from the ancient Greek words ἀμφί (near) and μήρυξ (ruminant). The type species A. murinus was previously recognized as a species of Dichobune by the French palaeontologist Georges Cuvier in 1822 before its eventual reclassification to its own genus. Two other species A. collotarsus and A. riparius are recognized also today although the former may be synonymous with A. murinus while the latter is known solely by a now-lost fossil specimen.
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