"Theria (/\u02C8\u03B8\u026A\u0259ri\u0259/; Greek: \u03B8\u03B7\u03C1\u03AF\u03BF\u03BD, wild beast) is a subclass of mammals that give birth to live young without using a shelled egg, consisting of the eutherians (including the placental mammals) and the metatherians (including the marsupials). The only omitted extant mammal group is the egg-laying monotremes.The earliest known therian mammal fossil is Juramaia, from the Middle Jurassic of China."@en . . .