Metatheria

(vertebrate zoology) An infraclass of therian mammals including a single order, the Marsupialia; distinguished by a small braincase, a total of 50 teeth, the inflected angular process of the mandible, and a pair of marsupial bones articulating with the pelvis.

An infraclass of therian mammals including a single order, the Marsupialia. The Metatheria are distinguished from the Eutheria (the placental mammals) by numerous characters. The braincase is small, the angular process of the mandible is inflected, and a pair of marsupial bones articulates with the pelvis. Almost all living marsupials have a pouch on the belly of the female in which the young are carried after birth. The early marsupials were unable to compete with the more progressive later placental forms and died out except in South America and Australia, where they were isolated by water barriers. See also Eutheria; Mammalia.

The noun has one meaning:

Meaning #1: pouched animals
  Synonym: subclass Metatheria

Metatheria
Female Eastern Grey Kangaroo with a joey in her pouch
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Subclass: Theria Infraclass: Metatheria Thomas Henry Huxley, 1880
Orders
Dasyuromorphia Didelphimorphia Diprotodontia Microbiotheria Notoryctemorphia Paucituberculata Peramelemorphia

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 (Illiger, 1811) though it is slightly wider. It also contains the nearest ancestors of marsupial mammals.

The earliest known representatives are known from the uppermost Lower Cretaceous of North America.

The closest living relatives of the metatheres are within Eutheria (also erected by Huxley in 1880). Both are sometimes united Infraclasses within the Subclass of Theria (Parker and Haswell, 1897), which contains all living mammals except monotremes.

The Greek words meta- and theria mean, in this case, the "other beasts".

See also

• Marsupial

References

• McKenna MC & Bell SK, (1997), Classification of Mammals Above the Species Level. Columbia University Press.zh-yue:後獸亞綱

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