of, denoting, or relating to the most recent geological era, which began 65 000 000 years ago: characterized by the development and increase of the mammals
noun
2. the Cenozoic
Word origin
C19: from Greek kainos new, recent + zōikos, from zōion animal
Cenozoic in American English
(ˌsinəˈzoʊɪk; ˌ sɛnəˈzoʊɪk)
adjective
[sometimesc-]
designating or of the third geologic era of the Phanerozoic Eon, usually subdivided into the Tertiary and Quaternary periods and characterized by the development of birds and mammals