Deltatheridium is an extinct species of metatheria

Metatheria

Metatheria is a grouping within the animal class Mammalia. First proposed by Thomas Henry Huxley in 1880, it is nearly synonymous with the earlier taxon Marsupialia though it is slightly wider since it also contains the nearest fossil relatives of marsupial mammals.The earliest known...

n. It lived in what is now Mongolia

Mongolia

Mongolia is a landlocked country in East and Central Asia. It is bordered by Russia to the north and China to the south, east and west. Although Mongolia does not share a border with Kazakhstan, its western-most point is only from Kazakhstan's eastern tip. Ulan Bator, the capital and largest...

 during the Upper Cretaceous

Cretaceous

The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...

. It was a basal metatherian, which places it near start of the linage that led to the marsupials, such the kangaroo

Kangaroo

A kangaroo is a marsupial from the family Macropodidae . In common use the term is used to describe the largest species from this family, especially those of the genus Macropus, Red Kangaroo, Antilopine Kangaroo, Eastern Grey Kangaroo and Western Grey Kangaroo. Kangaroos are endemic to the country...

, koala

Koala

The koala is an arboreal herbivorous marsupial native to Australia, and the only extant representative of the family Phascolarctidae....

, and opossum.

It had a length of 15 cm (5.9 in). Apart from preying on insects, its diet was also composed of small reptiles and what it could scavenge from carrion

Carrion

Carrion refers to the carcass of a dead animal. Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters include vultures, hawks, eagles, hyenas, Virginia Opossum, Tasmanian Devils, coyotes, Komodo dragons, and burying beetles...

 using its sharp canine teeth.

Other Mesozoic mammals from Mongolia

• Kamptobaatar
  Kamptobaatar
  Kamptobaatar is a Mongolian mammal genus from the Upper Cretaceous. It lived at the same time as the later dinosaurs. This animal was a member of the extinct order Multituberculata within the suborder Cimolodonta and family Sloanbaataridae....
  
  
• Zalambdalestes
  Zalambdalestes
  Zalambdalestes was a placental mammal living during the Upper Cretaceous in Mongolia. It is one of the oldest examples of a placental mammal known, and would have lived alongside the dinosaurs....