Cen·o·zo·ic (sĕn′ə-zōĭk, sē′nə-)
Of, relating to, or being the most recent era of geologic time, from about 66 million years ago to the present. The Cenozoic Era includes the Tertiary Period and the Quaternary Period and is characterized by the formation of modern continents, glaciation, and the diversification of mammals, birds, and plants. See Table at geologic time.
The Cenozoic Era.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The American Heritage Dictionary Blog
Check out our blog, updated regularly, for new words and revised definitions, interesting images from the 5th edition, discussions of usage, and more.