出典:Wikipedia
出典:『Wikipedia』 (2011/06/07 19:43 UTC 版)
Theria (
/ˈθɪəri.ə/; Greek: θηρίον, wild beast) is a subclass of mammals 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.