"the third great geological period," 1841, Cainozoic, from Latinized form of Greek kainos "new, fresh, recent, novel" (see recent) + zōon "animal," but here with a sense of "life" (from PIE root *gwei- "to live"). The era that began with the demise of the dinosaurs and the rise of "recent" species and continues to the present; it also is known as the Tertiary. Compare Paleozoic, Mesozoic.

We observe that Lyell, in his geological works, even the most recent, uses the word Cainozoic instead of Coenozoic or Cenozoic . Why the propounder of the terms Eocene , Miocene , etc., should thus spell the word is incomprehensible. If he is right in it, then to be consistent he ought to say Eocain , Miocain , Pliocain , Post-pliocain ; for all have the same root καινός . [American Journal of Sciences and Arts, 1873]