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Therians Fossil range: Early Cretaceous-Recent, 125–0 Ma PreЄ Є O S D C P T J K Pg N
A cat (Felis catus) with her kittens
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Subclass:	Theria Parker & Haswell, 1897 [1]
Infraclasses
Eutheria Metatheria

Theria (pronounced /ˈθɪərɪə/, from the Greek θηρίον, wild beast) is a subclass of mammals^[2] that give birth to live young without using a shelled egg, including both eutherians (placental mammals) and metatherians (marsupials and their ancestors).

Kangaroo, a marsupial, with her joey

Extent

Members of this subclass have external ears, most can suckle on a nipple, and have an ankle specialized for power and range of motion. Therians are often classified by their specialized dentition.

Almost all currently extant (not extinct) mammals are therians. The only known exceptions are the platypus and the echidnas (spiny anteater), both of which are prototherian monotremes.

Taxonomy

The rank of 'Theria' may vary depending on the classification system used. The textbook classification system by Vaughan et al. (2000)^[3] gives the following:

In the above system Theria is a subclass. Alternatively, in the system proposed by McKenna and Bell (1997)^[4] it is ranked as a supercohort under the subclass Theriiformes:

Another classification proposed by Luo et al. (2002)^[5] does not assign any rank to the taxonomic levels, but uses a purely cladistic system instead.

References

1. ^ ITIS Standard Report Page: Theria
2. ^ Myers, P., R. Espinosa, C. S. Parr, T. Jones, G. S. Hammond, and T. A. Dewey. "Subclass Theria". Animal Diversity Web. http://animaldiversity.ummz.umich.edu/site/accounts/classification/Theria.html.  
3. ^ Vaughan, Terry A., James M. Ryan, and Nicholas J. Czaplewski. 2000. Mammalogy: Fourth Edition. Saunders College Publishing, 565 pp. ISBN 0-03-025034-X
4. ^ McKenna, Malcolm C., and Bell, Susan K. 1997. Classification of Mammals Above the Species Level. Columbia University Press, New York, 631 pp. ISBN 0-231-11013-8
5. ^ Luo, Z.-X., Z. Kielan-Jaworowska, and R. L. Cifelli. 2002. In quest for a phylogeny of Mesozoic mammals. Acta Palaeontologica Polonica, 47:1-78.

Definition from Wiktionary, a free dictionary

Translingual

Wikipedia has an article on:

Theria

Wikipedia

Etymology

From Ancient Greek θηρίον (thērion), “‘wild beast’”).

Proper noun

Theria

1. A taxonomic subclass, within class Mammalia - the mammals that give birth to live young

Wikispecies has information on:

Theria

Wikispecies

See also

• Metatheria - Marsupialia
• Eutheria - Placentalia

From Wikispecies

Lagothrix lagotricha

Taxonavigation

Main Page
Cladus: Eukaryota
Supergroup: Unikonta
Cladus: Opisthokonta
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Superclassis: Tetrapoda
Classis: Mammalia
Subclassis: Theria
Infraclassis: Marsupialia (=Metatheria) - Placentalia (=Eutheria)

Name

Theria Parker & Haswell, 1897

References

• Theria Report on ITIS

Vernacular names

For more multimedia, look at Theria on Wikimedia Commons.