Theria

Theria ( /ˈθɪəriə/; 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). The only omitted extant mammal group is the egg-laying 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.

See also

• marsupials
• monotremes
• placental mammals