Science word of the day: CenozoicPronunciation: See-noh-ZOH'-ihkWhat it means: The ascendency of mammals, the birth of the Himalayas, the diversification of birds Earth's in its Cenozoic era, baby! The Cenozoic is the geological era happening right now. It started 66 million years ago with the abrupt mass extinction known as the Cretaceous-Paleogene extinction event, when a massive asteroid hit Earth and wiped out the nonavian dinosaurs. It's been a busy few tens of millions of years, ushering in such hits as Earth's first cacti, whales and most (if not all) of the Grand Canyon. How to use it in a sentence: The Cenozoic is called the Age of Mammals, but the University of California Museum of Paleontology in Berkeley would like you to know it could have been called the Age of Teleost Fish, if mammals weren't so dang self-centered. Can you crack our science word of the day puzzle, Chain Word?