The Collaborative International Dictionary of English v.0.48:
Mammal \Mam"mal\, n.; pl. Mammals. [L. mammalis belonging to the breast, fr. mamma the breast or pap: cf. F. mammal.] (Zool.) One of the Mammalia. [1913 Webster] Age of mammals. See under Age, n., 8. [1913 Webster]WordNet (r) 3.0 (2006):
Age of Mammals n 1: approximately the last 63 million years [syn: Cenozoic, Cenozoic era, Age of Mammals]