When was the Cretaceous period?
Cretaceous
a geologic period and system that spans 79 million years from the end of the Jurassic Period 145 million years ago (mya) to the beginning of the Paleogene Period 66 mya
The Cretaceous (/krɪˈteɪʃəs/, kri-TAY-shəs) is a geologic period and system that spans 79 million years from the end of the Jurassic Period 145 million years ago (mya) to the beginning of the Paleogene Period 66 mya.  It is the last period of the Mesozoic Era, and the longest period of the Phanerozoic Eon.  The Cretaceous Period is usually abbreviated K, for its German translation Kreide (chalk, creta in Latin).