The Cretaceous is a geological period that lasted from about 145 to 66 million years ago (mya). It is the third and final period of the Mesozoic Era, as well as the longest. At nearly 80 million years, it is the longest geological period of the entire Phanerozoic, almost surpassing the Ediacaran & Cryogenian in size. The name is derived from the Latin creta, 'chalk', which is abundant in the latter half of the period. It is usually abbreviated K, for its German translation Kreide.
