Metatheria is a mammalian clade that includes all mammals more closely related to marsupials than to placentals. First proposed by Thomas Henry Huxley in 1880, it is a more inclusive group than the marsupials; it contains all marsupials as well as many extinct non-marsupial relatives.
There are several hundred languages in China. The predominant language is Standard Chinese, which is based on Beijingese, but there are hundreds of related Chinese languages, collectively known as Hanyu, that are spoken by 92% of the population. The Chinese languages are typically divided into seven major language groups, and their study is a distinct academic discipline. They differ as much from each other morphologically and phonetically as do English, German and Danish, but meanwhile share the same writing system (Hanzi) and are mutually intelligible in written form. There are in addition approximately 300 minority languages spoken by the remaining 8% of the population of China. The ones with greatest state support are Mongolian, Tibetan, Uyghur and Zhuang.
Andrewsarchus is an extinct genus of mammal that lived during the Middle Eocene in China. It contains two species, A. mongoliensis and A. crassum. It was formerly placed in the families Mesonychidae or Arctocyonidae, but is now the sole member of a distinct family, Andrewsarchidae. It is most notable for being estimated as the largest terrestrial, carnivorous mammal, but that status has been disputed.
Simplicidentata is a group of mammals that includes the rodents and their closest extinct relatives. The term has historically been used as an alternative to Rodentia, contrasting the rodents with their close relatives the lagomorphs. However, Simplicidentata is now defined as including all members of Glires that share a more recent common ancestor with living rodents than with living lagomorphs. Thus, Simplicidentata is a total group that is more inclusive than Rodentia, a crown group that includes all living rodents, their last common ancestor, and all its descendants. Under this definition, the loss of the second pair of upper incisors is a synapomorphic feature of Simplicidentata. The loss of the second upper premolar (P2) has also been considered as synapomorphic for Simplicidentata, but the primitive simplicidentate Sinomylus does have a P2.
Mesonyx is a genus of extinct mesonychid mesonychian mammal: fossils of the various species are found in Early to Late Eocene-age strata in the United States and Early Eocene-aged strata in China, 51.8—51.7 Ma (AEO).
Sinonyx is a genus of extinct, superficially wolf-like mesonychid mammals from the late Paleocene of China. It is within the family Mesonychidae, and cladistic analysis of a skull of Sinonyxjiashanensis identifies its closest relative as Ankalagon. S.jiashanensis was discovered in Anhui province, China, in the Tuijinshan formation.
Pachyaena was a genus of heavily built, relatively short-legged mesonychids, early Cenozoic mammals that evolved before the origin of either modern hoofed animals or carnivores, and combined characteristics similar to both. The genus likely originated from Asia and spread to Europe, and from there to North America across a land bridge in what is now the North Atlantic ocean. Various described species of Pachyaena ranged in size from a coyote to a bear. However, recent work indicates that Pachyaena is paraphyletic, with P. ossifraga being closer to Synoplotherium, Harpagolestes and Mesonyx than to P. gigantea.
Hapalodectidae is an extinct family of relatively small-bodied mesonychian placental mammals from the Paleocene and Eocene of North America and Asia. Hapalodectids differ from the larger and better-known mesonychids by having teeth specialized for cutting, while the teeth of other mesonychids, such as Mesonyx or Sinonyx, are more specialized for crushing bones. Hapalodectids were once considered a subfamily of the Mesonychidae, but the discovery of a skull of Hapalodectes hetangensis showed additional differences justifying placement in a distinct family. In particular, H. hetangensis has a postorbital bar closing the back of the orbit, a feature lacking in mesonychids. The skeleton of hapalodectids is poorly known, and of the postcranial elements, only the humerus has been described. The morphology of this bone indicates less specialization for terrestrial locomotion than in mesonychids.
Ankalagon saurognathus is an extinct carnivorous mammal of the family Mesonychidae, endemic to North America during the Paleocene epoch, existing for approximately 3.1 million years.
The Khitan people were a historical nomadic people from Northeast Asia who, from the 4th century, inhabited an area corresponding to parts of modern Mongolia, Northeast China and the Russian Far East.
Gomphos is an extinct genus of early lagomorph from the early Eocene of the China and Mongolia.
Deltatheroida is an extinct group of basal metatherians that were distantly related to modern marsupials. The majority of known members of the group lived in the Cretaceous; one species, Gurbanodelta kara, is known from the late Paleocene (Gashatan) of China. Their fossils are restricted to Central Asia and North America. This order can be defined as all metatherians closer to Deltatheridium than to Marsupialia.
Asiatheriidae is a family of extinct metatherians in the order Asiadelphia known from Cretaceous Asia. Different from the Ameridelphia, they lacked a prominent distolateral process on the scaphoid bone and possessed a more slender fibula. Their dentition is different from most other marsupials.
The Irdin Manha Formation is a geological formation from the Eocene located in Inner Mongolia, China, a few kilometres south of the Mongolian border.
Harpagolestes is an extinct genus of hyena like, bear sized mesonychid mesonychian that lived in Central and Eastern Asia and western and central North America during the middle to late Eocene.
Mongolonyx is an extinct genus of carnivorous mesonychid mammal that lived during the Middle Eocene in Inner Mongolia (China) and became extinct during the Oligocene. It was described by Szalay and Gould.
Deltatheridiidae is an extinct family of basal carnivorous metatherians that lived in the Cretaceous and were closely related to marsupials. Their fossils are restricted to Central Asia and North America. They mostly disappeared in the KT event, but a ghost lineage, currently represented by Gurbanodelta, survived until the late Paleocene by decreasing in size and becoming insectivorous.
The "Gurlin Tsav" skull is a currently unnamed carnivorous metatherian fossil from the Nemegt Formation of Mongolia. Composed of a single semi-complete skull, this specimen is notable in regards to the evolution and systematics of Metatheria as a whole, and thus nigh-omnipresent in phylogenetic analyses of this group.
Patriomanidae is an extinct family of pangolins from superfamily Manoidea that includes two extinct genera Patriomanis and Cryptomanis.
Asiatherium is an extinct genus of mammal, probably belonging to Metatheria. It lived during the Late Cretaceous, and its fossilized remains were discovered in Mongolia.
