''Asiatherium'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of mammal, probably belonging to

Metatheria 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 wel ...

. It lived during the Late

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

, and its fossilized remains were discovered in

Mongolia Mongolia; Mongolian script: , , ; lit. "Mongol Nation" or "State of Mongolia" () is a landlocked country in East Asia, bordered by Russia to the north and China to the south. It covers an area of , with a population of just 3.3 million, ...

Description

Skull of ''Asiatherium'' is in length. This animal was roughly the size of a mouse, and is known from a fairly complete articulated skeleton, preserving a complete skull. Its teeth resembled roughly those of

marsupial Marsupials are any members of the mammalian infraclass Marsupialia. All extant marsupials are endemic to Australasia, Wallacea and the Americas. A distinctive characteristic common to most of these species is that the young are carried in a ...

s; it possessed three premolars and four molars, and the mandible was slightly curved. Compared to ''

Deltatheridium ''Deltatheridium'' (meaning ''triangle beast'' or ''delta beast'') is an extinct species of metatherian. It lived in what is now Mongolia during the Upper Cretaceous, ''circa'' 80 million years ago. A study in 2022 strongly suggested that De ...

'', ''Asiatherium'' was even more marsupial-like, due to its molars having paraconids lower than the metaconids, and the paired entoconid-hypoconulid cusps on the lower molars. The stylar platform of the upper molars was however narrower and the stylar cusps weaker than in primitive

s. The upper molars differed from those of marsupials in their expanded praecingula and postcingula.*F. S. Szalay and B. A. Trofimov. 1996. The Mongolian Late Cretaceous Asiatherium, and the early phylogeny and paleobiogeography of Metatheria. Journal of Vertebrate Paleontology 16(3):474-509

Classification

''Asiatherium reshetovi'' was first described in 1994, based on fossils found in the Udan-Sayr locality of the

Djadokhta Formation The Djadochta Formation (sometimes transcribed and also known as Djadokhta, Djadokata, or Dzhadokhtskaya) is a highly fossiliferous geological formation situated in Central Asia, Gobi Desert, dating from the Late Cretaceous period, about 75 mill ...

, in

. ''Asiatherium'' seems to be related to early marsupials, but probably was nested within a different clade of

Metatherian 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 ...

Deltatheroida 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 ( ...

, nested alongside

. The skeleton of ''Asiatherium'' looked like that of a basal

Theria Theria (; Greek: , wild beast) is a subclass of mammals amongst the Theriiformes. Theria includes the eutherians (including the placental mammals) and the metatherians (including the marsupials) but excludes the egg-laying monotremes. ...

n; epipubic bones, typical of marsupials, were present.

References and Bibliography

*B. A. Trofimov and F. S. Szalay. 1994. New Cretaceous marsupial from Mongolia and the early radiation of Metatheria. Proceedings of the National Academy of Sciences 91:12569-12573 *T. E. Williamson, S. L. Brusatte, T. D. Carr, A. Weil, and B. R. Standhardt. 2012. The phylogeny and evolution of Cretaceous–Palaeogene metatherians: cladistic analysis and description of new early Palaeocene specimens from the Nacimiento Formation, New Mexico. Journal of Systematic Palaeontology 10(4):625-651 {{Taxonbar, from=Q30895124 Cretaceous mammals Cretaceous mammals of Asia Prehistoric monotypic mammal genera Fossil taxa described in 1994 Prehistoric metatherians Prehistoric mammal genera